ISO 20816-1 \u2014 Machine Vibration Evaluation Standard Explained \u2014 Vibromera<\/title>\n<meta name=\"description\" content=\"Complete guide to ISO 20816-1: vibration zone checker, alarm calculator, unit converter. Covers evaluation zones A-D, dual criteria, casing vs shaft measurement, machine groups, ISO 10816 migration, and practical application with Balanset-1A.\">\n<meta name=\"keywords\" content=\"ISO 20816-1, ISO 20816, vibration evaluation, machine vibration, vibration zones, Zone A B C D, ISO 10816, ISO 7919, vibration severity, RMS velocity, shaft displacement, bearing vibration, acceptance testing, vibration limits, alarm setpoint, predictive maintenance, condition monitoring, Balanset-1A\">\n<meta name=\"author\" content=\"Vibromera\">\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large\">\n\n\n\n<meta property=\"og:type\" content=\"article\">\n<meta property=\"og:title\" content=\"ISO 20816-1 \u2014 Machine Vibration Evaluation: Zones, Criteria & Interactive Calculators\">\n<meta property=\"og:description\" content=\"Vibration zone checker, alarm setpoint calculator, unit converter. Complete guide to ISO 20816-1: evaluation zones, dual criteria, casing vs shaft measurement, machine groups.\">\n<meta property=\"og:url\" content=\"https:\/\/vibromera.eu\/glossary\/iso-20816-1\/\">\n<meta property=\"og:site_name\" content=\"Vibromera \u2014 Vibration Analysis & Balancing Equipment\">\n<meta property=\"og:locale\" content=\"en_US\">\n<meta property=\"og:image\" content=\"https:\/\/vibromera.eu\/wp-content\/uploads\/vibration-analysis-og.jpg\">\n<meta property=\"article:publisher\" content=\"https:\/\/vibromera.eu\/\">\n<meta property=\"article:section\" content=\"Glossary\">\n<meta property=\"article:tag\" content=\"ISO 20816-1\">\n<meta property=\"article:tag\" content=\"Vibration Standards\">\n<meta property=\"article:tag\" content=\"Machine Vibration\">\n<meta name=\"twitter:card\" content=\"summary_large_image\">\n<meta name=\"twitter:title\" content=\"ISO 20816-1 \u2014 Vibration Evaluation Guide with Zone Checker & Calculators\">\n<meta name=\"twitter:description\" content=\"Interactive zone checker, alarm calculator, unit converter. Complete guide to ISO 20816-1 standard for machine vibration evaluation.\">\n<meta name=\"geo.region\" content=\"EU\">\n<meta name=\"geo.placename\" content=\"Porto, Portugal\">\n<meta name=\"geo.position\" content=\"41.1579;-8.6291\">\n<meta name=\"ICBM\" content=\"41.1579, -8.6291\">\n<script type=\"application\/ld+json\">\n{\n \"@context\": \"https:\/\/schema.org\",\n \"@graph\": [\n {\n \"@type\": \"TechArticle\",\n \"@id\": \"https:\/\/vibromera.eu\/glossary\/iso-20816-1\/#article\",\n \"headline\": \"ISO 20816-1: Machine Vibration Evaluation Standard \u2014 Complete Guide\",\n \"description\": \"Comprehensive guide to ISO 20816-1 standard for measuring and evaluating machine vibration. Covers evaluation zones A-D, dual criteria (absolute limits and change from baseline), casing and shaft measurement, machine groups, alarm setpoints, and practical application.\",\n \"author\": {\n \"@type\": \"Organization\",\n \"name\": \"Vibromera\",\n \"url\": \"https:\/\/vibromera.eu\/\"\n },\n \"publisher\": {\n \"@type\": \"Organization\",\n \"name\": \"Vibromera\",\n \"url\": \"https:\/\/vibromera.eu\/\"\n },\n \"mainEntityOfPage\": \"https:\/\/vibromera.eu\/glossary\/iso-20816-1\/\",\n \"datePublished\": \"2025-03-10\",\n \"dateModified\": \"2026-02-09\",\n \"inLanguage\": \"en\",\n \"proficiencyLevel\": \"Beginner\",\n \"about\": [\n {\n \"@type\": \"Thing\",\n \"name\": \"ISO 20816-1\"\n },\n {\n \"@type\": \"Thing\",\n \"name\": \"Machine Vibration Evaluation\"\n },\n {\n \"@type\": \"Thing\",\n \"name\": \"Vibration Severity Assessment\"\n }\n ]\n },\n {\n \"@type\": \"FAQPage\",\n \"@id\": \"https:\/\/vibromera.eu\/glossary\/iso-20816-1\/#faq\",\n \"mainEntity\": [\n {\n \"@type\": \"Question\",\n \"name\": \"What is the difference between ISO 20816 and ISO 10816?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"ISO 20816 replaces and unifies two older standards: ISO 10816 (casing vibration on non-rotating parts) and ISO 7919 (shaft vibration on rotating parts). ISO 20816-1 combines both measurement philosophies into one framework. The zone boundary values from ISO 10816-3 are carried forward into ISO 20816-3 with minor updates.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What are the four vibration evaluation zones in ISO 20816?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Zone A (green): newly commissioned machines in good condition. Zone B (yellow): acceptable for unrestricted long-term operation. Zone C (orange): unsatisfactory for long-term operation, schedule corrective action. Zone D (red): severe enough to cause damage, take immediate action.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What vibration units does ISO 20816-1 use?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"For casing (bearing housing) measurements: broadband RMS velocity in mm\/s, typically over 10-1000 Hz range. For shaft measurements: peak-to-peak displacement in micrometers (\u03bcm), measured with proximity probes relative to the bearing housing.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What are the two evaluation criteria in ISO 20816?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Criterion 1: Absolute magnitude \u2014 compare measured vibration against fixed zone boundaries. Criterion 2: Change from baseline \u2014 evaluate change relative to established reference. Both must be used together. A significant change from baseline can indicate a developing fault even if the absolute value is still in Zone A or B.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What are the machine groups in ISO 20816-3?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Group 1: Large machines above 300 kW on rigid foundations. Group 2: Medium machines 15-300 kW on rigid foundations. Group 3: Large machines above 300 kW on flexible foundations. Group 4: Medium machines 15-300 kW on flexible foundations or special machines.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"Can I use the Balanset-1A for ISO 20816 vibration assessment?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Yes. The Balanset-1A measures broadband RMS velocity (the parameter specified by ISO 20816 for casing vibration) in its Vibrometer mode (F5). You can compare the measured value directly against the zone boundaries from ISO 20816-3 to assess machine condition.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What is the frequency range for ISO 20816 measurements?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"For casing vibration: 10-1000 Hz for most general machines, or 2-1000 Hz for low-speed machines. For shaft displacement: typically 1\u00d7 RPM and below for relative measurements. The exact range depends on the machine type and the specific part of the standard.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"How do I set alarm and trip levels using ISO 20816?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Alert (alarm) is typically set at the Zone B\/C boundary. Danger (trip) is set at the Zone C\/D boundary. 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Typically set at Zone B\/C boundary or at 2.0-2.5\u00d7 baseline value.\"\n },\n {\n \"@type\": \"DefinedTerm\",\n \"name\": \"Trip Setpoint\",\n \"description\": \"Vibration threshold that triggers automatic machine shutdown to prevent damage. Typically set at Zone C\/D boundary.\"\n }\n ]\n },\n {\n \"@type\": \"Product\",\n \"name\": \"Balanset-1A\",\n \"description\": \"Professional portable two-channel vibration analyzer and dynamic balancer with ISO 20816 severity assessment capability\",\n \"brand\": {\n \"@type\": \"Brand\",\n \"name\": \"Vibromera\"\n },\n \"url\": \"https:\/\/vibromera.eu\/product\/balanset-1\/\",\n \"offers\": {\n \"@type\": \"Offer\",\n \"url\": \"https:\/\/vibromera.eu\/product\/balanset-1\/\",\n \"priceCurrency\": \"EUR\",\n \"availability\": \"https:\/\/schema.org\/InStock\",\n \"price\": \"1975.00\",\n \"priceValidUntil\": \"2027-12-31\"\n }\n },\n {\n \"@type\": \"ItemList\",\n \"name\": \"ISO 20816-1 Guide Contents\",\n \"numberOfItems\": 10,\n \"itemListElement\": [\n {\n \"@type\": \"ListItem\",\n \"position\": 1,\n \"name\": \"Interactive Calculators\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 2,\n \"name\": \"What Is ISO 20816-1\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 3,\n \"name\": \"The ISO 20816 Series\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 4,\n \"name\": \"Measurement Types\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 5,\n \"name\": \"Evaluation Zones A-D\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 6,\n \"name\": \"Evaluation Criteria\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 7,\n \"name\": \"Machine Groups\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 8,\n \"name\": \"Alarm & Trip Setpoints\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 9,\n \"name\": \"Migration from ISO 10816\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 10,\n \"name\": \"FAQ\"\n }\n ]\n }\n ]\n}\n<\/script>\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Serif+Display&family=Source+Sans+3:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500;600&display=swap\" 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a{color:var(--blue);text-decoration:none;font-weight:500}.page-footer p{font-size:14px;color:var(--text-muted)}\n@media(max-width:1200px){.container,.hero-inner,.quick-nav-inner{padding:0 32px}.content-layout{grid-template-columns:1fr 260px;gap:32px}.calc-grid{grid-template-columns:1fr 1fr}.related-grid{grid-template-columns:repeat(2,1fr)}}\n@media(max-width:960px){.content-layout{grid-template-columns:1fr}.toc-sidebar{position:static;order:-1}.calc-grid{grid-template-columns:1fr}}\n@media(max-width:768px){.container,.hero-inner,.quick-nav-inner{padding:0 20px}.hero{padding:36px 0 32px}.hero h1{font-size:28px}.hero .subtitle{font-size:16px}.article-content h2{font-size:24px}.calc-row{grid-template-columns:1fr}.result-grid{grid-template-columns:1fr}table{font-size:13px}table th,table td{padding:8px 10px}.formula-box{padding:18px 20px}.formula-box .formula-main{font-size:16px}.shop-cta h2{font-size:24px}.related-grid{grid-template-columns:1fr}}\n@media(max-width:480px){.hero h1{font-size:24px}.quick-nav a{padding:12px 12px;font-size:13px}}\n@media print{.quick-nav,.shop-cta,.toc-sidebar,.calc-panel{display:none}}\n<\/style>\n<\/head>\n<body>\n\n<header class=\"hero\">\n<div class=\"hero-inner\">\n<div class=\"breadcrumb\"><a href=\"https:\/\/vibromera.eu\/\">Home<\/a> \u2192 <a href=\"https:\/\/vibromera.eu\/glossary\/\">Glossary<\/a> \u2192 ISO 20816-1<\/div>\n<h1>ISO 20816-1 \u2014 <span>Machine Vibration<\/span> Evaluation Standard<\/h1>\n<div class=\"canon-badge\"><span style=\"font-size:14px;\">\ud83d\udccc<\/span> Canonical Reference Article \u2014 vibromera.eu<\/div>\n<div class=\"subtitle\">Complete guide to the modern unified standard for measuring and evaluating machinery vibration. Replaces ISO 10816-1 and ISO 7919-1. Interactive zone checker, alarm calculator, and vibration unit converter.<\/div>\n<\/div>\n<\/header>\n\n<nav class=\"quick-nav\"><div class=\"quick-nav-inner\">\n<a href=\"#calculators\">\ud83e\uddee Calculators<\/a>\n<a href=\"#what-is\">\ud83d\udcc4 What Is ISO 20816<\/a>\n<a href=\"#series\">\ud83d\udcda 20816 Series<\/a>\n<a href=\"#measurement\">\ud83d\udccf Measurement Types<\/a>\n<a href=\"#zones\">\ud83d\udea6 Zones A\u2013D<\/a>\n<a href=\"#criteria\">\ud83d\udcca Dual Criteria<\/a>\n<a href=\"#groups\">\ud83c\udfed Machine Groups<\/a>\n<a href=\"#alarms\">\ud83d\udd14 Alarm & Trip<\/a>\n<a href=\"#acceptance\">\u2705 Acceptance Testing<\/a>\n<a href=\"#migration\">\ud83d\udd04 ISO 10816 Migration<\/a>\n<a href=\"#balanset\">\ud83d\udd27 Balanset-1A<\/a>\n<a href=\"#faq\">\u2753 FAQ<\/a>\n<\/div><\/nav>\n\n\n<section class=\"section-bg\" id=\"calculators\">\n<div class=\"container\">\n<div class=\"section-header\">\n<h2>Vibration Assessment Tools<\/h2>\n<p>ISO 20816-3 zone checker, alarm setpoint calculator, and vibration unit converter<\/p>\n<\/div>\n<div class=\"calc-grid\">\n\n\n<div class=\"calc-panel\">\n<div class=\"calc-header\">\ud83d\udea6 ISO 20816-3 Casing Vibration Zone Checker<\/div>\n<div class=\"calc-body\">\n<div class=\"calc-form\">\n<div>\n<label>Machine Group<\/label>\n<select id=\"zc-group\" onchange=\"calcZone()\">\n<option value=\"1\">Group 1 \u2014 Large rigid foundation (>300 kW)<\/option>\n<option value=\"2\" selected>Group 2 \u2014 Medium rigid foundation (15\u2013300 kW)<\/option>\n<option value=\"3\">Group 3 \u2014 Large flexible foundation (>300 kW)<\/option>\n<option value=\"4\">Group 4 \u2014 Medium flexible\/special (15\u2013300 kW)<\/option>\n<\/select>\n<\/div>\n<div>\n<label>Measured RMS Velocity (mm\/s)<\/label>\n<input type=\"number\" id=\"zc-vel\" value=\"3.2\" step=\"0.1\" oninput=\"calcZone()\">\n<\/div>\n<button class=\"calc-btn\" onclick=\"calcZone()\">Check Zone<\/button>\n<\/div>\n<div class=\"severity-bar\">\n<div class=\"sev-zone sev-a\">A<\/div><div class=\"sev-zone sev-b\">B<\/div><div class=\"sev-zone sev-c\">C<\/div><div class=\"sev-zone sev-d\">D<\/div>\n<\/div>\n<div class=\"results-panel\" id=\"zc-results\">\n<div class=\"result-grid\">\n<div class=\"result-card primary\">\n<div class=\"r-label\">Assessment<\/div>\n<div class=\"r-value\" id=\"zc-zone\">\u2014<\/div>\n<div class=\"r-unit\" id=\"zc-action\">\u2014<\/div>\n<\/div>\n<div class=\"result-card\"><div class=\"r-label\">A\/B Boundary<\/div><div class=\"r-value\" id=\"zc-ab\">\u2014<\/div><div class=\"r-unit\">mm\/s<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">B\/C Boundary<\/div><div class=\"r-value\" id=\"zc-bc\">\u2014<\/div><div class=\"r-unit\">mm\/s (Alert)<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">C\/D Boundary<\/div><div class=\"r-value\" id=\"zc-cd\">\u2014<\/div><div class=\"r-unit\">mm\/s (Trip)<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Margin to Alert<\/div><div class=\"r-value\" id=\"zc-margin\">\u2014<\/div><div class=\"r-unit\">mm\/s remaining<\/div><\/div>\n<\/div>\n<div class=\"severity-result\" id=\"zc-severity\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"calc-panel\">\n<div class=\"calc-header\">\ud83d\udd14 Alarm Setpoint Calculator<\/div>\n<div class=\"calc-body\">\n<div class=\"calc-form\">\n<div><label>Baseline Vibration (mm\/s RMS)<\/label><input type=\"number\" id=\"al-base\" value=\"1.5\" step=\"0.1\" oninput=\"calcAlarm()\"><\/div>\n<div class=\"calc-row\">\n<div><label>Alert Multiplier<\/label>\n<select id=\"al-mult\" onchange=\"calcAlarm()\">\n<option value=\"2.0\">2.0\u00d7 (conservative)<\/option>\n<option value=\"2.5\" selected>2.5\u00d7 (standard)<\/option>\n<option value=\"3.0\">3.0\u00d7 (relaxed)<\/option>\n<\/select><\/div>\n<div><label>Machine Group<\/label>\n<select id=\"al-group\" onchange=\"calcAlarm()\">\n<option value=\"1\">Group 1<\/option>\n<option value=\"2\" selected>Group 2<\/option>\n<option value=\"3\">Group 3<\/option>\n<option value=\"4\">Group 4<\/option>\n<\/select><\/div>\n<\/div>\n<button class=\"calc-btn\" onclick=\"calcAlarm()\">Calculate Setpoints<\/button>\n<\/div>\n<div class=\"results-panel\" id=\"al-results\">\n<div class=\"result-grid\">\n<div class=\"result-card\"><div class=\"r-label\">Relative Alert (Criterion 2)<\/div><div class=\"r-value\" id=\"al-rel-alert\">\u2014<\/div><div class=\"r-unit\">mm\/s (baseline \u00d7 multiplier)<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Absolute Alert (B\/C boundary)<\/div><div class=\"r-value\" id=\"al-abs-alert\">\u2014<\/div><div class=\"r-unit\">mm\/s (Criterion 1)<\/div><\/div>\n<div class=\"result-card primary\"><div class=\"r-label\">Recommended Alert Setpoint<\/div><div class=\"r-value\" id=\"al-alert\">\u2014<\/div><div class=\"r-unit\">mm\/s \u2014 whichever is LOWER<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Trip Setpoint (C\/D boundary)<\/div><div class=\"r-value\" id=\"al-trip\">\u2014<\/div><div class=\"r-unit\">mm\/s<\/div><\/div>\n<\/div>\n<div style=\"margin-top:12px;font-size:13px;color:var(--text-muted);line-height:1.5;\">\n<strong>Logic:<\/strong> Alert = whichever is lower between the relative (baseline \u00d7 multiplier) and absolute (B\/C boundary) value. This ensures early warning regardless of which criterion triggers first. Trip is always the C\/D boundary.\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"calc-panel\">\n<div class=\"calc-header\">\ud83d\udd04 Vibration Unit Converter<\/div>\n<div class=\"calc-body\">\n<div class=\"calc-form\">\n<div class=\"calc-row\">\n<div><label>Value<\/label><input type=\"number\" id=\"uc-val\" value=\"4.5\" step=\"0.01\" oninput=\"calcUnits()\"><\/div>\n<div><label>Input Unit<\/label>\n<select id=\"uc-from\" onchange=\"calcUnits()\">\n<option value=\"vel\" selected>mm\/s RMS (velocity)<\/option>\n<option value=\"disp\">\u03bcm peak-peak (displacement)<\/option>\n<option value=\"acc\">m\/s\u00b2 RMS (acceleration)<\/option>\n<option value=\"g\">g RMS (acceleration)<\/option>\n<option value=\"ips\">in\/s peak (IPS)<\/option>\n<option value=\"mil\">mils peak-peak<\/option>\n<\/select><\/div>\n<\/div>\n<div><label>Vibration Frequency (Hz) \u2014 required for conversion between parameters<\/label><input type=\"number\" id=\"uc-freq\" value=\"25\" step=\"0.1\" oninput=\"calcUnits()\"><\/div>\n<button class=\"calc-btn\" onclick=\"calcUnits()\">Convert<\/button>\n<\/div>\n<div class=\"results-panel\" id=\"uc-results\">\n<div class=\"result-grid\">\n<div class=\"result-card\"><div class=\"r-label\">Velocity (RMS)<\/div><div class=\"r-value\" id=\"uc-vel\">\u2014<\/div><div class=\"r-unit\">mm\/s<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Displacement (pk-pk)<\/div><div class=\"r-value\" id=\"uc-disp\">\u2014<\/div><div class=\"r-unit\">\u03bcm<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Acceleration (RMS)<\/div><div class=\"r-value\" id=\"uc-acc\">\u2014<\/div><div class=\"r-unit\">m\/s\u00b2<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Acceleration (RMS)<\/div><div class=\"r-value\" id=\"uc-g\">\u2014<\/div><div class=\"r-unit\">g<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">IPS (peak)<\/div><div class=\"r-value\" id=\"uc-ips\">\u2014<\/div><div class=\"r-unit\">in\/s peak<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Mils (pk-pk)<\/div><div class=\"r-value\" id=\"uc-mil\">\u2014<\/div><div class=\"r-unit\">mils pk-pk<\/div><\/div>\n<\/div>\n<div style=\"margin-top:12px;font-size:13px;color:var(--text-muted);line-height:1.5;\">\n<strong>Note:<\/strong> Conversions between displacement, velocity, and acceleration assume <em>sinusoidal<\/em> vibration at the specified frequency. Real vibration contains multiple frequencies \u2014 use spectrum analysis for precision. IPS peak = mm\/s RMS \u00d7 0.0557. Mils pk-pk = \u03bcm pk-pk \/ 25.4.\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"calc-panel\">\n<div class=\"calc-header\">\ud83d\udce1 Shaft Displacement Zone Checker (ISO 7919 \/ 20816)<\/div>\n<div class=\"calc-body\">\n<div class=\"calc-form\">\n<div><label>Machine Type<\/label>\n<select id=\"sd-type\" onchange=\"calcShaft()\">\n<option value=\"turbo\" selected>Steam\/gas turbine, turbo-generator<\/option>\n<option value=\"hydro\">Hydraulic turbine\/generator (vertical)<\/option>\n<option value=\"pump-gen\">Pumps, compressors (general)<\/option>\n<\/select><\/div>\n<div class=\"calc-row\">\n<div><label>Shaft Speed (RPM)<\/label><input type=\"number\" id=\"sd-rpm\" value=\"3000\" oninput=\"calcShaft()\"><\/div>\n<div><label>Measured Displacement (\u03bcm pk-pk)<\/label><input type=\"number\" id=\"sd-disp\" value=\"85\" step=\"1\" oninput=\"calcShaft()\"><\/div>\n<\/div>\n<button class=\"calc-btn\" onclick=\"calcShaft()\">Check Zone<\/button>\n<\/div>\n<div class=\"severity-bar\">\n<div class=\"sev-zone sev-a\">A<\/div><div class=\"sev-zone sev-b\">B<\/div><div class=\"sev-zone sev-c\">C<\/div><div class=\"sev-zone sev-d\">D<\/div>\n<\/div>\n<div class=\"results-panel\" id=\"sd-results\">\n<div class=\"result-grid\">\n<div class=\"result-card primary\"><div class=\"r-label\">Assessment<\/div><div class=\"r-value\" id=\"sd-zone\">\u2014<\/div><div class=\"r-unit\" id=\"sd-action\">\u2014<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">A\/B Boundary<\/div><div class=\"r-value\" id=\"sd-ab\">\u2014<\/div><div class=\"r-unit\">\u03bcm pk-pk<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">B\/C (Alert)<\/div><div class=\"r-value\" id=\"sd-bc\">\u2014<\/div><div class=\"r-unit\">\u03bcm pk-pk<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">C\/D (Trip)<\/div><div class=\"r-value\" id=\"sd-cd\">\u2014<\/div><div class=\"r-unit\">\u03bcm pk-pk<\/div><\/div>\n<\/div>\n<div class=\"severity-result\" id=\"sd-severity\"><\/div>\n<div style=\"margin-top:12px;font-size:13px;color:var(--text-muted);line-height:1.5;\">\nZone boundaries for turbo-machinery are speed-dependent: limits = k \u00d7 \u221a(9000\/RPM). Values shown are approximate per ISO 7919-2 \/ ISO 20816-2.\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n<\/div>\n<\/div>\n<\/section>\n\n\n<main class=\"main-content\">\n<div class=\"container\">\n<div class=\"content-layout\">\n<article class=\"article-content\">\n\n<h2 id=\"what-is\">What Is ISO 20816-1?<\/h2>\n\n<p><strong>ISO 20816-1:2016<\/strong> (full title: \"Mechanical vibration \u2014 Measurement and evaluation of machine vibration \u2014 Part 1: General guidelines\") is the current international standard providing the framework for how machinery vibration should be measured and evaluated. It was published in 2016 and replaces two older foundational standards that had been in use since the 1990s.<\/p>\n\n<p>The most significant change is the <strong>unification<\/strong> of two previously separate measurement philosophies into a single, cohesive document:<\/p>\n<ul>\n<li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/iso-10816-1\/\">ISO 10816-1<\/a><\/strong> \u2014 covered vibration measured on <em>non-rotating parts<\/em> (bearing housings, machine casing) using seismic sensors (accelerometers).<\/li>\n<li><strong>ISO 7919-1<\/strong> \u2014 covered vibration measured on <em>rotating shafts<\/em> using non-contact proximity probes.<\/li>\n<\/ul>\n\n<p>ISO 20816-1 combines both approaches into one framework, recognizing that comprehensive machine assessment often requires both types of measurement. A machine might have acceptable casing vibration but dangerous shaft movement (indicating a rotor-dynamic problem), or vice versa (indicating a structural\/foundation issue). Only by evaluating both can you get the full picture.<\/p>\n\n<div class=\"info-box\">\n<div class=\"box-title\">\ud83d\udca1 Key Takeaway<\/div>\n<p>ISO 20816-1 is a <em>general guidelines<\/em> document. It defines the <strong>concepts, methodology, and evaluation framework<\/strong> (zones, criteria, measurement types) but does NOT contain specific numerical limits. The actual zone boundary values for specific machine types are in the other parts of the series (ISO 20816-2 through 20816-9). For most industrial machines, <strong>ISO 20816-3<\/strong> provides the numbers.<\/p>\n<\/div>\n\n<h3>What the Standard Covers<\/h3>\n<ol>\n<li><strong>Scope and measurement types<\/strong> \u2014 defines both casing and shaft vibration measurement methodologies<\/li>\n<li><strong>Instrumentation requirements<\/strong> \u2014 sensor types, frequency ranges, calibration, mounting standards<\/li>\n<li><strong>Evaluation criteria<\/strong> \u2014 the two-criterion approach (absolute limits + change from baseline)<\/li>\n<li><strong>Evaluation zones<\/strong> \u2014 the four-zone classification system (A, B, C, D)<\/li>\n<li><strong>Combined assessment and acceptance<\/strong> \u2014 how to use both measurement types together, acceptance testing vs. operational monitoring<\/li>\n<\/ol>\n\n<h2 id=\"series\">The Complete ISO 20816 Series<\/h2>\n\n<p>ISO 20816 is a multi-part standard. Part 1 provides the general framework; other parts provide specific numerical limits for different machine categories.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">ISO 20816 Series \u2014 All Parts<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Part<\/th><th>Title \/ Scope<\/th><th>Replaces<\/th><th>Status<\/th><\/tr><\/thead>\n<tbody>\n<tr><td class=\"mono\"><strong>20816-1<\/strong><\/td><td>General guidelines<\/td><td>ISO 10816-1 + ISO 7919-1<\/td><td>Published 2016<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-2<\/strong><\/td><td>Land-based gas turbines, steam turbines, generators >40 MW<\/td><td>ISO 10816-2 + ISO 7919-2<\/td><td>Published 2017<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-3<\/strong><\/td><td>Industrial machines with power >15 kW and speed 120\u201315000 RPM<\/td><td>ISO 10816-3 + ISO 7919-3<\/td><td>Published 2022<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-4<\/strong><\/td><td>Gas turbine driven sets (excluding aircraft derivatives)<\/td><td>ISO 10816-4 + ISO 7919-4<\/td><td>Published 2018<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-5<\/strong><\/td><td>Hydraulic machine sets including pumps >15 kW<\/td><td>ISO 10816-5 + ISO 7919-5<\/td><td>Published 2018<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-6<\/strong><\/td><td>Reciprocating machines >100 kW<\/td><td>ISO 10816-6<\/td><td>Published 2016<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-7<\/strong><\/td><td>Rotodynamic pumps (industrial, including measurements on rotating shafts)<\/td><td>ISO 10816-7<\/td><td>Published 2017<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-8<\/strong><\/td><td>Reciprocating compressor systems<\/td><td>ISO 10816-8<\/td><td>Published 2018<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-9<\/strong><\/td><td>Gear units<\/td><td>New (no predecessor)<\/td><td>Published 2020<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-21<\/strong><\/td><td>Onshore wind turbines (horizontal axis, \u2265100 kW)<\/td><td>New<\/td><td>Published 2015<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box warning\">\n<div class=\"box-title\">\u26a0\ufe0f ISO 10816-3 vs. ISO 20816-3<\/div>\n<p>ISO 10816-3:2009 was formally withdrawn when ISO 20816-3:2022 was published. However, ISO 10816-3 zone boundaries remain widely used in industry because they are well-established and most monitoring systems are configured with them. The casing vibration limits in ISO 20816-3 are very similar (in many cases identical) to ISO 10816-3. If your existing monitoring program uses ISO 10816-3 values, there is no urgent need to change \u2014 but new installations should reference ISO 20816-3.<\/p>\n<\/div>\n\n<h2 id=\"measurement\">Measurement Types<\/h2>\n\n<p>ISO 20816-1 formally unifies two fundamentally different measurement approaches. Understanding the distinction is critical for correct application.<\/p>\n\n<h3>Casing Vibration (Non-Rotating Parts)<\/h3>\n\n<ul>\n<li><strong>What:<\/strong> Vibration of the stationary machine structure \u2014 bearing housings, pedestals, frames, casing.<\/li>\n<li><strong>Sensor:<\/strong> Seismic transducers \u2014 piezoelectric accelerometers (most common) or velocity transducers \u2014 mounted on the bearing housing per <a href=\"https:\/\/vibromera.eu\/glossary\/iso-5348\/\">ISO 5348<\/a>.<\/li>\n<li><strong>Parameter:<\/strong> <strong>Broadband RMS velocity<\/strong> in <strong>mm\/s<\/strong> (or in\/s in some regions).<\/li>\n<li><strong>Frequency range:<\/strong> 10\u20131000 Hz standard; 2\u20131000 Hz for low-speed machines (<120 RPM).<\/li>\n<li><strong>What it tells you:<\/strong> The vibration energy being transmitted into the machine structure. Reflects the forces acting on bearings and the structural response. Directly correlates with bearing fatigue and structural damage risk.<\/li>\n<li><strong>Equipment:<\/strong> The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> measures broadband RMS velocity in its Vibrometer mode (F5), making it directly suitable for ISO 20816 casing assessment.<\/li>\n<\/ul>\n\n<h3>Shaft Vibration (Rotating Parts)<\/h3>\n\n<ul>\n<li><strong>What:<\/strong> Dynamic displacement of the shaft relative to the bearing housing \u2014 how much the shaft actually moves within its bearing clearance.<\/li>\n<li><strong>Sensor:<\/strong> Non-contact eddy-current proximity probes, typically installed in orthogonal pairs (X-Y) at each bearing per API 670.<\/li>\n<li><strong>Parameter:<\/strong> <strong>Peak-to-peak displacement<\/strong> in <strong>\u03bcm<\/strong> (micrometers) or mils (1 mil = 25.4 \u03bcm).<\/li>\n<li><strong>Frequency range:<\/strong> Primarily shaft synchronous (1\u00d7) and sub-synchronous components.<\/li>\n<li><strong>What it tells you:<\/strong> The actual rotor dynamic behavior \u2014 orbit shape, whirl direction, rub contact. Critical for detecting shaft bow, oil whirl, seal contact, and misalignment that may not transfer efficiently to the casing.<\/li>\n<li><strong>Equipment:<\/strong> Permanently installed proximity probes (not typically portable instruments). Primarily used on large turbo-machinery with fluid-film (journal) bearings.<\/li>\n<\/ul>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Casing vs. Shaft Vibration \u2014 Comparison<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Aspect<\/th><th>Casing (Non-Rotating Parts)<\/th><th>Shaft (Rotating Parts)<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Sensor<\/strong><\/td><td>Accelerometer \/ velocity transducer<\/td><td>Proximity probe (eddy current)<\/td><\/tr>\n<tr><td><strong>Mounting<\/strong><\/td><td>On bearing housing (external)<\/td><td>Inside bearing housing (internal)<\/td><\/tr>\n<tr><td><strong>Parameter<\/strong><\/td><td>RMS velocity (mm\/s)<\/td><td>Peak-to-peak displacement (\u03bcm)<\/td><\/tr>\n<tr><td><strong>Frequency range<\/strong><\/td><td>10\u20131000 Hz (broadband)<\/td><td>Sub-synchronous to 1\u00d7 RPM<\/td><\/tr>\n<tr><td><strong>Detects best<\/strong><\/td><td>Unbalance, misalignment, looseness, bearing defects, structural resonance<\/td><td>Shaft bow, oil whirl\/whip, seal rub, rotor instability, journal bearing condition<\/td><\/tr>\n<tr><td><strong>Typical machines<\/strong><\/td><td>All \u2014 fans, pumps, motors, compressors, general industrial<\/td><td>Large turbo-machinery with journal bearings<\/td><\/tr>\n<tr><td><strong>Portable measurement<\/strong><\/td><td>Yes (Balanset-1A, portable analyzers)<\/td><td>Permanently installed probes only<\/td><\/tr>\n<tr><td><strong>Standard reference<\/strong><\/td><td>Formerly ISO 10816, now ISO 20816<\/td><td>Formerly ISO 7919, now ISO 20816<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box success\">\n<div class=\"box-title\">\u2705 Why Both Matter<\/div>\n<p>A machine can have <strong>low casing vibration but high shaft displacement<\/strong> \u2014 the forces aren't being transmitted to the structure (e.g., very stiff bearing housing), but the shaft is moving dangerously inside the bearing clearance. Conversely, <strong>high casing vibration with normal shaft displacement<\/strong> suggests a structural problem (loose foundation, resonance) rather than a rotor-dynamic issue. ISO 20816-1 recommends evaluating both wherever possible for a complete diagnosis.<\/p>\n<\/div>\n\n<h3>Instrumentation Requirements<\/h3>\n<p>The standard specifies that the entire measurement chain \u2014 transducer, cabling, signal conditioning, and analyzer \u2014 must be calibrated and capable of accurately measuring over the required frequency range. Key references:<\/p>\n<ul>\n<li><strong>Accelerometer mounting:<\/strong> Per <a href=\"https:\/\/vibromera.eu\/glossary\/iso-5348\/\">ISO 5348<\/a> \u2014 stud mount preferred, magnetic acceptable for routine monitoring, adhesive for permanent installation.<\/li>\n<li><strong>Proximity probe installation:<\/strong> Per API 670 \u2014 probe gap, target surface finish, orthogonal pair orientation, and cable routing requirements.<\/li>\n<li><strong>Calibration:<\/strong> Regular calibration of the entire chain against traceable standards. The Balanset-1A ships factory-calibrated and can be verified against known vibration sources.<\/li>\n<\/ul>\n\n<h2 id=\"zones\">Evaluation Zones A, B, C, D<\/h2>\n\n<p>The four-zone system is the most recognized feature of the ISO vibration standards. It provides a universal, color-coded framework for classifying vibration severity and determining appropriate action.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Zone Definitions and Required Actions<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th style=\"width:8%\">Zone<\/th><th style=\"width:12%\">Color<\/th><th>Machine Condition<\/th><th>Required Action<\/th><\/tr><\/thead>\n<tbody>\n<tr><td class=\"zone-a\">A<\/td><td><span class=\"zone-badge za\">GREEN<\/span><\/td><td>Vibration of newly commissioned or reconditioned machines. Excellent condition.<\/td><td>Normal operation. Establish this as baseline for future trending. Target condition after maintenance.<\/td><\/tr>\n<tr><td class=\"zone-b\">B<\/td><td><span class=\"zone-badge zb\">YELLOW<\/span><\/td><td>Acceptable for unrestricted long-term operation. Normal wear-in condition.<\/td><td>Continue operation. Monitor trends \u2014 movement toward Zone C requires investigation. Acceptable for most operational machines.<\/td><\/tr>\n<tr><td class=\"zone-c\">C<\/td><td><span class=\"zone-badge zc\">ORANGE<\/span><\/td><td>Unsatisfactory for long-term continuous operation. Developing fault or deteriorating condition.<\/td><td><strong>Plan corrective action.<\/strong> Increase monitoring frequency. Investigate root cause. Schedule maintenance at next available opportunity.<\/td><\/tr>\n<tr><td class=\"zone-d\">D<\/td><td><span class=\"zone-badge zd\">RED<\/span><\/td><td>Sufficiently severe to cause damage. Risk of catastrophic failure.<\/td><td><strong>Take immediate action.<\/strong> Consider emergency shutdown. Do not continue operation \u2014 damage to bearings, seals, and structural components is occurring.<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<h3>Zone Boundary Values \u2014 Casing Vibration (ISO 20816-3)<\/h3>\n\n<p>These are the specific numerical limits for <strong>broadband RMS velocity on bearing housings<\/strong>, applicable to industrial machines with power above 15 kW and speeds from 120 to 15,000 RPM. These values were originally established in ISO 10816-3 and are carried forward with minor updates in ISO 20816-3:2022.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">ISO 20816-3 \u2014 Casing Vibration Zone Boundaries (mm\/s RMS)<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Zone Boundary<\/th><th>Group 1<br>Large, rigid<br>(>300 kW)<\/th><th>Group 2<br>Medium, rigid<br>(15\u2013300 kW)<\/th><th>Group 3<br>Large, flexible<br>(>300 kW)<\/th><th>Group 4<br>Medium, flexible<br>(15\u2013300 kW)<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>A\/B<\/strong><\/td><td class=\"mono zone-a\">2.3<\/td><td class=\"mono zone-a\">1.4<\/td><td class=\"mono zone-a\">3.5<\/td><td class=\"mono zone-a\">2.3<\/td><\/tr>\n<tr><td><strong>B\/C<\/strong> (Alert)<\/td><td class=\"mono zone-b\">4.5<\/td><td class=\"mono zone-b\">2.8<\/td><td class=\"mono zone-b\">7.1<\/td><td class=\"mono zone-b\">4.5<\/td><\/tr>\n<tr><td><strong>C\/D<\/strong> (Trip)<\/td><td class=\"mono zone-c\">7.1<\/td><td class=\"mono zone-c\">7.1<\/td><td class=\"mono zone-c\">11.2<\/td><td class=\"mono zone-c\">11.2<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box\">\n<div class=\"box-title\">\ud83d\udca1 How to Read This Table<\/div>\n<p><strong>Example:<\/strong> You measure 3.2 mm\/s RMS on a 55 kW motor bolted to a concrete floor. This is Group 2 (medium power, rigid foundation). A\/B boundary = 1.4, B\/C = 2.8, C\/D = 7.1. Your reading of 3.2 exceeds 2.8 (B\/C) but is below 7.1 (C\/D), so the machine is in <strong>Zone C<\/strong> \u2014 schedule corrective action. Use the calculator above to check any value instantly.<\/p>\n<\/div>\n\n<h3>Zone Boundary Values \u2014 Shaft Displacement (ISO 20816-2)<\/h3>\n\n<p>For turbo-machinery with proximity probes, shaft displacement limits are speed-dependent. The standard uses a formula based on the square root of speed ratio.<\/p>\n\n<div class=\"formula-box\">\n<div class=\"formula-label\">Shaft Displacement Zone Boundaries (Turbo-machinery)<\/div>\n<div class=\"formula-main\">S<sub>boundary<\/sub> = k \u00d7 \u221a(9000 \/ n)<\/div>\n<div class=\"formula-note\">k = zone coefficient (varies by zone boundary and machine type) | n = shaft speed in RPM<br>Result in \u03bcm peak-to-peak | Higher speed \u2192 tighter limits<\/div>\n<\/div>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Approximate Shaft Displacement Boundaries \u2014 Large Steam\/Gas Turbines<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Zone Boundary<\/th><th>k Factor<\/th><th>@ 1500 RPM<\/th><th>@ 3000 RPM<\/th><th>@ 6000 RPM<\/th><th>@ 10000 RPM<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>A\/B<\/strong><\/td><td class=\"mono\">50<\/td><td class=\"mono zone-a\">122 \u03bcm<\/td><td class=\"mono zone-a\">87 \u03bcm<\/td><td class=\"mono zone-a\">61 \u03bcm<\/td><td class=\"mono zone-a\">47 \u03bcm<\/td><\/tr>\n<tr><td><strong>B\/C<\/strong> (Alert)<\/td><td class=\"mono\">80<\/td><td class=\"mono zone-b\">196 \u03bcm<\/td><td class=\"mono zone-b\">139 \u03bcm<\/td><td class=\"mono zone-b\">98 \u03bcm<\/td><td class=\"mono zone-b\">76 \u03bcm<\/td><\/tr>\n<tr><td><strong>C\/D<\/strong> (Trip)<\/td><td class=\"mono\">100<\/td><td class=\"mono zone-c\">245 \u03bcm<\/td><td class=\"mono zone-c\">173 \u03bcm<\/td><td class=\"mono zone-c\">122 \u03bcm<\/td><td class=\"mono zone-c\">95 \u03bcm<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<h2 id=\"criteria\">The Two Evaluation Criteria<\/h2>\n\n<p>ISO 20816-1 mandates that vibration assessment must consider <strong>both<\/strong> criteria simultaneously. Using only one gives an incomplete picture.<\/p>\n\n<h3>Criterion 1 \u2014 Absolute Magnitude<\/h3>\n\n<p>Compare the measured vibration value against the fixed zone boundaries from the applicable part of ISO 20816. This tells you the machine's condition relative to the general population of similar machines.<\/p>\n\n<ul>\n<li><strong>Use for:<\/strong> Acceptance testing of new\/repaired machines, baseline assessment, setting trip alarms, comparing machines across a fleet.<\/li>\n<li><strong>Limitation:<\/strong> A machine that has always been at 4.0 mm\/s (Zone B for Group 1) might be perfectly healthy \u2014 that's its normal operating level. Criterion 1 alone doesn't tell you if something has changed.<\/li>\n<\/ul>\n\n<h3>Criterion 2 \u2014 Change from Baseline<\/h3>\n\n<p>Compare the current vibration to an established reference (baseline) value. The baseline is typically measured after commissioning, after maintenance, or as a statistical average over a stable operating period.<\/p>\n\n<ul>\n<li><strong>Use for:<\/strong> Trend-based predictive maintenance, early fault detection, detecting deterioration regardless of absolute level.<\/li>\n<li><strong>Key insight:<\/strong> A significant <em>change<\/em> in vibration \u2014 even if the absolute value is still in Zone A or B \u2014 is often the <strong>earliest and most reliable indicator<\/strong> of a developing fault.<\/li>\n<\/ul>\n\n<div class=\"info-box warning\">\n<div class=\"box-title\">\u26a0\ufe0f Why Criterion 2 Is Often More Important<\/div>\n<p><strong>Scenario:<\/strong> A pump has a baseline of 1.0 mm\/s. Over three weeks, it rises to 2.5 mm\/s. By Criterion 1 (Group 2), 2.5 mm\/s is still in Zone B \u2014 \"acceptable.\" But by Criterion 2, the vibration has <em>increased 2.5\u00d7<\/em> from baseline, which is a significant change indicating a developing fault (possibly bearing wear or misalignment). Without Criterion 2, you would miss this alarm until the machine deteriorates further into Zone C or D.<\/p>\n<\/div>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Criterion 1 vs. Criterion 2 \u2014 Comparison<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Aspect<\/th><th>Criterion 1 \u2014 Absolute<\/th><th>Criterion 2 \u2014 Change from Baseline<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Reference<\/strong><\/td><td>Fixed zone boundaries from standard<\/td><td>Machine's own established baseline<\/td><\/tr>\n<tr><td><strong>Best for<\/strong><\/td><td>Acceptance testing, fleet comparison, trip alarms<\/td><td>Predictive maintenance, early fault detection, trending<\/td><\/tr>\n<tr><td><strong>Alert trigger<\/strong><\/td><td>Value exceeds B\/C boundary<\/td><td>Value exceeds 2.0\u20132.5\u00d7 baseline<\/td><\/tr>\n<tr><td><strong>Strength<\/strong><\/td><td>Objective, universal benchmark<\/td><td>Sensitive to change, machine-specific<\/td><\/tr>\n<tr><td><strong>Weakness<\/strong><\/td><td>Doesn't detect change from \"normal\" baseline<\/td><td>Requires established baseline; false alarms if baseline not stable<\/td><\/tr>\n<tr><td><strong>In ISO 20816<\/strong><\/td><td>Zone A\/B\/C\/D boundaries<\/td><td>\"Significant change\" threshold (standard recommends 2.0\u20132.5\u00d7)<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<h2 id=\"groups\">Machine Groups (ISO 20816-3)<\/h2>\n\n<p>ISO 20816-3 (and its predecessor ISO 10816-3) classifies machines into four groups based on <strong>power rating<\/strong> and <strong>foundation type<\/strong>. The zone boundaries are different for each group because larger machines on flexible foundations naturally have higher vibration than small machines on rigid foundations.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Machine Group Classification<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Group<\/th><th>Power<\/th><th>Foundation<\/th><th>Typical Machines<\/th><th>A\/B<\/th><th>B\/C<\/th><th>C\/D<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Group 1<\/strong><\/td><td>>300 kW<\/td><td>Rigid<\/td><td>Large motors, generators, turbo-compressors on concrete base<\/td><td class=\"mono\">2.3<\/td><td class=\"mono\">4.5<\/td><td class=\"mono\">7.1<\/td><\/tr>\n<tr><td><strong>Group 2<\/strong><\/td><td>15\u2013300 kW<\/td><td>Rigid<\/td><td>Standard motors, pumps, fans on concrete or heavy steel frame<\/td><td class=\"mono\">1.4<\/td><td class=\"mono\">2.8<\/td><td class=\"mono\">7.1<\/td><\/tr>\n<tr><td><strong>Group 3<\/strong><\/td><td>>300 kW<\/td><td>Flexible<\/td><td>Large machines on steel structures, offshore platforms, upper floors<\/td><td class=\"mono\">3.5<\/td><td class=\"mono\">7.1<\/td><td class=\"mono\">11.2<\/td><\/tr>\n<tr><td><strong>Group 4<\/strong><\/td><td>15\u2013300 kW<\/td><td>Flexible<\/td><td>Medium machines on flexible frames, skid-mounted equipment<\/td><td class=\"mono\">2.3<\/td><td class=\"mono\">4.5<\/td><td class=\"mono\">11.2<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box\">\n<div class=\"box-title\">\ud83d\udca1 How to Determine the Foundation Type<\/div>\n<p><strong>Rigid foundation:<\/strong> The foundation's lowest natural frequency is well above the machine's operating speed. Practically: heavy concrete block, thick steel baseplate grouted to concrete. The foundation doesn't amplify or modify the machine's vibration.<br>\n<strong>Flexible foundation:<\/strong> The foundation has natural frequencies near or below the machine's operating speed. Practically: elevated steel platform, lightweight frame, spring-mounted skid, upper-floor installation. The foundation can amplify or attenuate vibration at certain frequencies.<\/p>\n<p>If in doubt, a simple test: measure vibration on the foundation surface next to the machine. If it's significantly lower than on the bearing housing, the foundation is likely rigid. If it's similar, the foundation may be acting as a flexible mount.<\/p>\n<\/div>\n\n<h2 id=\"alarms\">Alarm and Trip Setpoints<\/h2>\n\n<p>The practical application of ISO 20816 in monitoring systems requires setting <strong>Alert<\/strong> (alarm) and <strong>Danger<\/strong> (trip) setpoints. The standard provides guidance for both absolute and relative setpoints.<\/p>\n\n<h3>Absolute Setpoints (from Criterion 1)<\/h3>\n<ul>\n<li><strong>Alert<\/strong> = B\/C zone boundary value. When vibration exceeds this, increase monitoring, investigate root cause, plan corrective action.<\/li>\n<li><strong>Trip<\/strong> = C\/D zone boundary value. When vibration exceeds this, automatic shutdown (if available) or immediate manual action to prevent damage.<\/li>\n<\/ul>\n\n<h3>Relative Setpoints (from Criterion 2)<\/h3>\n<ul>\n<li><strong>Relative Alert<\/strong> = Baseline \u00d7 multiplier (typically 2.0\u20132.5\u00d7). A doubling or more of vibration from baseline indicates a developing fault.<\/li>\n<li>The <strong>effective alert setpoint<\/strong> should be whichever is <em>lower<\/em> between the absolute alert and the relative alert. This ensures the first criterion to be violated triggers the alarm.<\/li>\n<\/ul>\n\n<div class=\"info-box success\">\n<div class=\"box-title\">\u2705 Practical Setpoint Example<\/div>\n<p><strong>Machine:<\/strong> 75 kW motor, rigid foundation (Group 2). Baseline after commissioning: 1.2 mm\/s RMS.<br>\n<strong>Absolute alert<\/strong> (B\/C boundary, Group 2): 2.8 mm\/s<br>\n<strong>Relative alert<\/strong> (baseline \u00d7 2.5): 1.2 \u00d7 2.5 = 3.0 mm\/s<br>\n<strong>Effective alert<\/strong> = 2.8 mm\/s (lower of the two)<br>\n<strong>Trip<\/strong> (C\/D boundary): 7.1 mm\/s<br><br>\nIf this motor's vibration rises to 2.9 mm\/s, both criteria are violated \u2014 take action.<\/p>\n<\/div>\n\n<h2 id=\"acceptance\">Acceptance Testing vs. Operational Monitoring<\/h2>\n\n<p>ISO 20816-1 clearly distinguishes between two assessment contexts:<\/p>\n\n<h3>Acceptance Testing<\/h3>\n<p>Used when commissioning new machines or accepting machines after overhaul. The requirement is typically that vibration falls within <strong>Zone A or Zone B<\/strong>. This is a strict pass\/fail criterion \u2014 a new machine delivered in Zone C would normally be rejected.<\/p>\n<ul>\n<li>Measurement conditions must be tightly controlled (stable speed, full load, thermal equilibrium).<\/li>\n<li>Multiple readings at each measurement point.<\/li>\n<li>Results documented in a formal acceptance report.<\/li>\n<\/ul>\n\n<h3>Operational Monitoring<\/h3>\n<p>Used for ongoing condition assessment of in-service machines. The focus shifts from pass\/fail to <strong>trending and change detection<\/strong> (Criterion 2). Alert and trip setpoints are the primary tools.<\/p>\n<ul>\n<li>Portable route-based data collection (Balanset-1A) or permanent online monitoring.<\/li>\n<li>Consistent measurement points, conditions, and procedures for valid trend comparison.<\/li>\n<li>Action decisions based on both absolute zone and trend direction.<\/li>\n<\/ul>\n\n<h2 id=\"migration\">Migration from ISO 10816 to ISO 20816<\/h2>\n\n<p>Many facilities still reference ISO 10816 in their procedures, monitoring databases, and specifications. Here's what you need to know about the transition.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">ISO 10816 \u2192 ISO 20816 Migration Map<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Old Standard<\/th><th>New Standard<\/th><th>Impact on Zone Values<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>ISO 10816-1:1995<\/td><td>ISO 20816-1:2016<\/td><td>General guidelines \u2014 no numerical values to change<\/td><\/tr>\n<tr><td>ISO 10816-2:2009<\/td><td>ISO 20816-2:2017<\/td><td>Some limits revised for modern turbo-machinery<\/td><\/tr>\n<tr><td>ISO 10816-3:2009<\/td><td>ISO 20816-3:2022<\/td><td>Casing velocity limits largely unchanged; shaft limits added<\/td><\/tr>\n<tr><td>ISO 10816-4:2009<\/td><td>ISO 20816-4:2018<\/td><td>Updated with shaft displacement criteria<\/td><\/tr>\n<tr><td>ISO 10816-5:2000<\/td><td>ISO 20816-5:2018<\/td><td>Revised for hydraulic machines<\/td><\/tr>\n<tr><td>ISO 10816-6:1995<\/td><td>ISO 20816-6:2016<\/td><td>Minor updates for reciprocating machines<\/td><\/tr>\n<tr><td>ISO 10816-7:2009<\/td><td>ISO 20816-7:2017<\/td><td>Updated pump evaluation criteria<\/td><\/tr>\n<tr><td>ISO 10816-8:2014<\/td><td>ISO 20816-8:2018<\/td><td>Reciprocating compressors \u2014 minor changes<\/td><\/tr>\n<tr><td>ISO 7919-1 through -5<\/td><td>Merged into 20816 series<\/td><td>Shaft displacement criteria now in same documents as casing<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box\">\n<div class=\"box-title\">\ud83d\udca1 Practical Migration Advice<\/div>\n<p><strong>For existing monitoring programs:<\/strong> If your systems are configured with ISO 10816-3 zone values, the casing vibration limits are essentially unchanged in ISO 20816-3. No urgent reconfiguration needed. Update reference numbers in documentation when convenient.<br>\n<strong>For new installations:<\/strong> Specify ISO 20816-3 (2022) as the reference standard. Consider adding shaft displacement monitoring where applicable (large machines with journal bearings).<br>\n<strong>For specifications and contracts:<\/strong> Update references from \"ISO 10816\" to \"ISO 20816\" in new purchase orders and maintenance contracts. Include both casing and shaft criteria where relevant.<\/p>\n<\/div>\n\n<h2 id=\"balanset\">Practical Application with Balanset-1A<\/h2>\n\n<p>The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> portable vibration analyzer directly supports ISO 20816 casing vibration assessment through its built-in measurement modes.<\/p>\n\n<h4>Vibrometer Mode (F5)<\/h4>\n<p>Measures <strong>broadband RMS velocity<\/strong> \u2014 the exact parameter specified by ISO 20816 for casing vibration. Display shows:<\/p>\n<ul>\n<li><strong>V1s<\/strong> (overall vibration) \u2014 compare directly with zone boundaries<\/li>\n<li><strong>V1o<\/strong> (1\u00d7 RPM component) \u2014 indicates how much of the total vibration is from unbalance<\/li>\n<li>Both channels simultaneously \u2014 near and far bearing in one measurement<\/li>\n<\/ul>\n\n<h4>Spectrum Analyzer (F1 \/ F8)<\/h4>\n<p>Displays the FFT frequency spectrum, allowing you to identify the <em>source<\/em> of high vibration (unbalance at 1\u00d7, misalignment at 2\u00d7, bearing defects at characteristic frequencies). See the <a href=\"https:\/\/vibromera.eu\/glossary\/vibration-analysis\/\">Vibration Analysis Guide<\/a> for spectrum interpretation.<\/p>\n\n<h4>Balancing Mode<\/h4>\n<p>If vibration is diagnosed as unbalance (dominant 1\u00d7 RPM peak), the Balanset-1A can immediately proceed to field balancing to correct it \u2014 reducing vibration from Zone C or D back to Zone A or B. See the <a href=\"https:\/\/vibromera.eu\/glossary\/balancing\/\">Field Dynamic Balancing Guide<\/a> for the complete procedure.<\/p>\n\n<div class=\"action-box\">\n<p><strong>Workflow:<\/strong> Measure (F5) \u2192 Diagnose zone \u2192 If Zone C\/D and 1\u00d7 dominant \u2192 Analyze spectrum (F1) \u2192 Balance \u2192 Verify back in Zone A\/B.<\/p>\n<\/div>\n\n<h2 id=\"faq\">Frequently Asked Questions<\/h2>\n\n<p><strong>What is the difference between ISO 20816 and ISO 10816?<\/strong><\/p>\n<p>ISO 20816 replaces ISO 10816 by combining casing vibration (formerly ISO 10816) and shaft vibration (formerly ISO 7919) into a unified standard. The zone boundary values for casing vibration in ISO 20816-3 are very similar to those in ISO 10816-3. The main improvement is the integration of both measurement philosophies in one document.<\/p>\n\n<p><strong>Is ISO 10816 still valid?<\/strong><\/p>\n<p>ISO 10816 parts have been formally withdrawn as they are superseded by corresponding ISO 20816 parts. However, the vibration limits are widely embedded in existing monitoring systems and contracts. The numerical values for casing vibration are essentially unchanged, so existing ISO 10816-based programs remain technically valid in practice.<\/p>\n\n<p><strong>Which parameter should I measure \u2014 velocity or displacement?<\/strong><\/p>\n<p>For general industrial machines with rolling-element bearings measured externally (portable instruments): <strong>RMS velocity in mm\/s<\/strong>. For large turbo-machinery with journal bearings and installed proximity probes: <strong>peak-to-peak shaft displacement in \u03bcm<\/strong>. If both are available, evaluate both \u2014 they provide complementary information.<\/p>\n\n<p><strong>How do I determine the machine group?<\/strong><\/p>\n<p>Two factors: power rating (above or below 300 kW) and foundation type (rigid or flexible). A 75 kW motor bolted to a concrete pad = Group 2. A 500 kW compressor on a steel platform = Group 3. See the Machine Groups section above.<\/p>\n\n<p><strong>Can a machine in Zone B still have a developing fault?<\/strong><\/p>\n<p>Yes \u2014 this is exactly why Criterion 2 exists. If a machine's baseline was 0.8 mm\/s and it rises to 2.2 mm\/s, it's still in Zone B for Group 2 (below 2.8 mm\/s), but the 2.75\u00d7 increase from baseline indicates a significant developing problem.<\/p>\n\n<p><strong>What vibration level should I target after balancing?<\/strong><\/p>\n<p>After field balancing, aim for <strong>Zone A<\/strong> (below the A\/B boundary for your machine group). For a Group 2 machine, this means below 1.4 mm\/s. The <a href=\"https:\/\/vibromera.eu\/glossary\/balancing\/\">Balancing Guide<\/a> covers the procedure in detail.<\/p>\n\n<p><strong>What frequency range does the broadband RMS velocity cover?<\/strong><\/p>\n<p>Standard range is 10\u20131000 Hz per ISO 20816-1. This captures the most common fault signatures: 1\u00d7 to ~60\u00d7 for a machine running at 1000 RPM (~17 Hz), or 1\u00d7 to ~20\u00d7 for a machine at 3000 RPM (50 Hz). Low-speed machines (<120 RPM) use an extended range of 2\u20131000 Hz.<\/p>\n\n<p><strong>Do I need to buy the ISO 20816-1 document to use the zone values?<\/strong><\/p>\n<p>ISO 20816-1 itself does not contain specific zone values \u2014 it only defines the methodology. The zone boundary numbers are in <strong>ISO 20816-3<\/strong> (for general industrial machines). For the complete official documents with all procedures and annexes, purchase from <a href=\"https:\/\/www.iso.org\/standard\/63180.html\" rel=\"nofollow noopener\" target=\"_blank\">ISO Store<\/a>. The zone values published in this guide are from publicly available references and widely used in industry.<\/p>\n\n<hr style=\"margin:48px 0 24px;border:none;border-top:1px solid var(--border-light);\">\n\n<h3>Related Articles<\/h3>\n<div class=\"related-grid\">\n<a href=\"https:\/\/vibromera.eu\/glossary\/vibration-analysis\/\" class=\"related-card\">\n<div class=\"rc-title\">Vibration Analysis Guide<\/div>\n<div class=\"rc-desc\">FFT spectrum interpretation, bearing frequency calculator, fault diagnosis patterns<\/div>\n<\/a>\n<a href=\"https:\/\/vibromera.eu\/glossary\/balancing\/\" class=\"related-card\">\n<div class=\"rc-title\">Field Dynamic Balancing<\/div>\n<div class=\"rc-desc\">ISO 1940-1 tolerance calculator, two-plane procedure with Balanset-1A<\/div>\n<\/a>\n<a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\" class=\"related-card\">\n<div class=\"rc-title\">Balanset-1A Device<\/div>\n<div class=\"rc-desc\">Two-channel portable vibration analyzer and balancer \u2014 specifications and ordering<\/div>\n<\/a>\n<\/div>\n\n<hr style=\"margin:24px 0;border:none;border-top:1px solid var(--border-light);\">\n<p><a href=\"https:\/\/vibromera.eu\/glossary\/\">\u2190 Back to Glossary Index<\/a><\/p>\n\n<\/article>\n\n<aside class=\"toc-sidebar\">\n<div class=\"toc-box\">\n<h3>On This Page<\/h3>\n<a href=\"#calculators\">Calculators<\/a>\n<a class=\"sub\" href=\"#calculators\">Zone checker<\/a>\n<a class=\"sub\" href=\"#calculators\">Alarm setpoint<\/a>\n<a class=\"sub\" href=\"#calculators\">Unit converter<\/a>\n<a class=\"sub\" href=\"#calculators\">Shaft displacement<\/a>\n<a href=\"#what-is\">What Is ISO 20816-1<\/a>\n<a href=\"#series\">The 20816 Series<\/a>\n<a class=\"sub\" href=\"#series\">All parts table<\/a>\n<a href=\"#measurement\">Measurement Types<\/a>\n<a class=\"sub\" href=\"#measurement\">Casing vibration<\/a>\n<a class=\"sub\" href=\"#measurement\">Shaft vibration<\/a>\n<a class=\"sub\" href=\"#measurement\">Instrumentation<\/a>\n<a href=\"#zones\">Evaluation Zones A\u2013D<\/a>\n<a class=\"sub\" href=\"#zones\">Zone definitions<\/a>\n<a class=\"sub\" href=\"#zones\">Casing boundaries (20816-3)<\/a>\n<a class=\"sub\" href=\"#zones\">Shaft boundaries (20816-2)<\/a>\n<a href=\"#criteria\">Dual Criteria<\/a>\n<a class=\"sub\" href=\"#criteria\">Criterion 1 \u2014 Absolute<\/a>\n<a class=\"sub\" href=\"#criteria\">Criterion 2 \u2014 Change<\/a>\n<a href=\"#groups\">Machine Groups<\/a>\n<a href=\"#alarms\">Alarm & Trip Setpoints<\/a>\n<a href=\"#acceptance\">Acceptance vs Monitoring<\/a>\n<a href=\"#migration\">ISO 10816 Migration<\/a>\n<a href=\"#balanset\">Balanset-1A Application<\/a>\n<a href=\"#faq\">FAQ<\/a>\n<\/div>\n<\/aside>\n\n<\/div>\n<\/div>\n<\/main>\n\n<section class=\"shop-cta\">\n<div class=\"container\">\n<h2>Measure Vibration Per ISO 20816<\/h2>\n<p>The Balanset-1A measures broadband RMS velocity \u2014 the exact parameter specified by ISO 20816 for casing vibration assessment. Two channels, FFT spectrum, and built-in balancing capability.<\/p>\n<a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\" class=\"cta-btn\">View Balanset-1A Device \u2192<\/a>\n<\/div>\n<\/section>\n\n<footer class=\"page-footer\">\n<div class=\"container\">\n<p>\u00a9 2025 Vibromera. <a href=\"https:\/\/vibromera.eu\/glossary\/\">Glossary Index<\/a> \u00b7 <a href=\"https:\/\/vibromera.eu\/\">vibromera.eu<\/a><\/p>\n<\/div>\n<\/footer>\n\n<script>\n\/* Zone boundaries: [A\/B, B\/C, C\/D] per group *\/\nvar ZB={1:[2.3,4.5,7.1],2:[1.4,2.8,7.1],3:[3.5,7.1,11.2],4:[2.3,4.5,11.2]};\n\n\/* ===== ZONE CHECKER ===== *\/\nfunction calcZone(){\n var g=parseInt(document.getElementById('zc-group').value);\n var v=parseFloat(document.getElementById('zc-vel').value)||0;\n var b=ZB[g];\n var zone,action,cls;\n if(v<=b[0]){zone='Zone A';action='Excellent \u2014 newly commissioned condition';cls='zone-a';}\n else if(v<=b[1]){zone='Zone B';action='Acceptable for unrestricted long-term operation';cls='zone-b';}\n else if(v<=b[2]){zone='Zone C';action='Unsatisfactory \u2014 plan corrective action';cls='zone-c';}\n else{zone='Zone D';action='SEVERE \u2014 take immediate action \/ shutdown';cls='zone-d';}\n document.getElementById('zc-zone').textContent=zone+' ('+v+' mm\/s)';\n document.getElementById('zc-action').textContent=action;\n document.getElementById('zc-ab').textContent=b[0];\n document.getElementById('zc-bc').textContent=b[1];\n document.getElementById('zc-cd').textContent=b[2];\n var margin=b[1]-v;\n document.getElementById('zc-margin').textContent=margin>0?margin.toFixed(1):'EXCEEDED';\n var sev=document.getElementById('zc-severity');\n sev.className='severity-result '+cls;\n sev.textContent=zone+' \u2014 Group '+g+': '+action;\n document.getElementById('zc-results').classList.add('active');\n}\n\n\/* ===== ALARM SETPOINT ===== *\/\nfunction calcAlarm(){\n var base=parseFloat(document.getElementById('al-base').value)||0;\n var mult=parseFloat(document.getElementById('al-mult').value)||2.5;\n var g=parseInt(document.getElementById('al-group').value);\n var b=ZB[g];\n var relAlert=base*mult;\n var absAlert=b[1];\n var trip=b[2];\n var effective=Math.min(relAlert,absAlert);\n document.getElementById('al-rel-alert').textContent=relAlert.toFixed(1);\n document.getElementById('al-abs-alert').textContent=absAlert.toFixed(1);\n document.getElementById('al-alert').textContent=effective.toFixed(1);\n document.getElementById('al-trip').textContent=trip.toFixed(1);\n document.getElementById('al-results').classList.add('active');\n}\n\n\/* ===== UNIT CONVERTER ===== *\/\nfunction calcUnits(){\n var val=parseFloat(document.getElementById('uc-val').value)||0;\n var from=document.getElementById('uc-from').value;\n var freq=parseFloat(document.getElementById('uc-freq').value)||1;\n var omega=2*Math.PI*freq;\n \/* Convert everything to mm\/s RMS first *\/\n var velRMS;\n switch(from){\n case 'vel': velRMS=val; break;\n case 'disp': velRMS=(val\/1000)*omega\/Math.sqrt(2)*1000*Math.PI; \/* \u03bcm pk-pk to mm\/s RMS *\/ velRMS=val*omega\/(2*Math.sqrt(2)*1000); break;\n case 'acc': velRMS=val*1000\/omega; break;\n case 'g': velRMS=val*9810\/omega; break;\n case 'ips': velRMS=val*25.4\/Math.sqrt(2); break;\n case 'mil': var um=val*25.4; velRMS=um*omega\/(2*Math.sqrt(2)*1000); break;\n }\n \/* From mm\/s RMS to all others *\/\n var dispPP=velRMS*2*Math.sqrt(2)*1000\/omega; \/* \u03bcm pk-pk *\/\n var accRMS=velRMS*omega\/1000; \/* m\/s\u00b2 *\/\n var gRMS=accRMS\/9.81;\n var ipsPk=velRMS*Math.sqrt(2)\/25.4;\n var milPP=dispPP\/25.4;\n document.getElementById('uc-vel').textContent=velRMS.toFixed(3);\n document.getElementById('uc-disp').textContent=dispPP.toFixed(1);\n document.getElementById('uc-acc').textContent=accRMS.toFixed(3);\n document.getElementById('uc-g').textContent=gRMS.toFixed(4);\n document.getElementById('uc-ips').textContent=ipsPk.toFixed(4);\n document.getElementById('uc-mil').textContent=milPP.toFixed(2);\n document.getElementById('uc-results').classList.add('active');\n}\n\n\/* ===== SHAFT DISPLACEMENT ZONE CHECKER ===== *\/\nfunction calcShaft(){\n var type=document.getElementById('sd-type').value;\n var rpm=parseFloat(document.getElementById('sd-rpm').value)||1;\n var disp=parseFloat(document.getElementById('sd-disp').value)||0;\n \/* k factors [A\/B, B\/C, C\/D] *\/\n var k;\n switch(type){\n case 'turbo': k=[50,80,100]; break;\n case 'hydro': k=[60,100,125]; break;\n case 'pump-gen': k=[55,90,110]; break;\n }\n var factor=Math.sqrt(9000\/rpm);\n var ab=k[0]*factor, bc=k[1]*factor, cd=k[2]*factor;\n var zone,action,cls;\n if(disp<=ab){zone='Zone A';action='Excellent shaft condition';cls='zone-a';}\n else if(disp<=bc){zone='Zone B';action='Acceptable for long-term operation';cls='zone-b';}\n else if(disp<=cd){zone='Zone C';action='Unsatisfactory \u2014 investigate and plan action';cls='zone-c';}\n else{zone='Zone D';action='SEVERE \u2014 risk of rub\/damage, consider shutdown';cls='zone-d';}\n document.getElementById('sd-zone').textContent=zone+' ('+disp+' \u03bcm)';\n document.getElementById('sd-action').textContent=action;\n document.getElementById('sd-ab').textContent=Math.round(ab);\n document.getElementById('sd-bc').textContent=Math.round(bc);\n document.getElementById('sd-cd').textContent=Math.round(cd);\n var sev=document.getElementById('sd-severity');\n sev.className='severity-result '+cls;\n sev.textContent=zone+' \u2014 '+action;\n document.getElementById('sd-results').classList.add('active');\n}\n\ndocument.addEventListener('DOMContentLoaded',function(){calcZone();calcAlarm();calcUnits();calcShaft();});\n<\/script>\n<\/body>\n<\/html><\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>An overview of ISO 20816-1, the current standard for the measurement and evaluation of machine vibration, covering both non-rotating parts and rotating shafts.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[109,112],"tags":[],"class_list":["post-12","glossary","type-glossary","status-publish","hentry","category-glossary","category-iso-standards"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/glossary\/12","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/types\/glossary"}],"version-history":[{"count":7,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/glossary\/12\/revisions"}],"predecessor-version":[{"id":101736,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/glossary\/12\/revisions\/101736"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/media?parent=12"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/categories?post=12"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/tags?post=12"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

\n\n\n\n\nISO 20816-1 \u2014 Machine Vibration Evaluation Standard Explained \u2014 Vibromera<\/title>\n<meta name=\"description\" content=\"Complete guide to ISO 20816-1: vibration zone checker, alarm calculator, unit converter. Covers evaluation zones A-D, dual criteria, casing vs shaft measurement, machine groups, ISO 10816 migration, and practical application with Balanset-1A.\">\n<meta name=\"keywords\" content=\"ISO 20816-1, ISO 20816, vibration evaluation, machine vibration, vibration zones, Zone A B C D, ISO 10816, ISO 7919, vibration severity, RMS velocity, shaft displacement, bearing vibration, acceptance testing, vibration limits, alarm setpoint, predictive maintenance, condition monitoring, Balanset-1A\">\n<meta name=\"author\" content=\"Vibromera\">\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large\">\n\n\n\n<meta property=\"og:type\" content=\"article\">\n<meta property=\"og:title\" content=\"ISO 20816-1 \u2014 Machine Vibration Evaluation: Zones, Criteria & Interactive Calculators\">\n<meta property=\"og:description\" content=\"Vibration zone checker, alarm setpoint calculator, unit converter. Complete guide to ISO 20816-1: evaluation zones, dual criteria, casing vs shaft measurement, machine groups.\">\n<meta property=\"og:url\" content=\"https:\/\/vibromera.eu\/glossary\/iso-20816-1\/\">\n<meta property=\"og:site_name\" content=\"Vibromera \u2014 Vibration Analysis & Balancing Equipment\">\n<meta property=\"og:locale\" content=\"en_US\">\n<meta property=\"og:image\" content=\"https:\/\/vibromera.eu\/wp-content\/uploads\/vibration-analysis-og.jpg\">\n<meta property=\"article:publisher\" content=\"https:\/\/vibromera.eu\/\">\n<meta property=\"article:section\" content=\"Glossary\">\n<meta property=\"article:tag\" content=\"ISO 20816-1\">\n<meta property=\"article:tag\" content=\"Vibration Standards\">\n<meta property=\"article:tag\" content=\"Machine Vibration\">\n<meta name=\"twitter:card\" content=\"summary_large_image\">\n<meta name=\"twitter:title\" content=\"ISO 20816-1 \u2014 Vibration Evaluation Guide with Zone Checker & Calculators\">\n<meta name=\"twitter:description\" content=\"Interactive zone checker, alarm calculator, unit converter. Complete guide to ISO 20816-1 standard for machine vibration evaluation.\">\n<meta name=\"geo.region\" content=\"EU\">\n<meta name=\"geo.placename\" content=\"Porto, Portugal\">\n<meta name=\"geo.position\" content=\"41.1579;-8.6291\">\n<meta name=\"ICBM\" content=\"41.1579, -8.6291\">\n<script type=\"application\/ld+json\">\n{\n \"@context\": \"https:\/\/schema.org\",\n \"@graph\": [\n {\n \"@type\": \"TechArticle\",\n \"@id\": \"https:\/\/vibromera.eu\/glossary\/iso-20816-1\/#article\",\n \"headline\": \"ISO 20816-1: Machine Vibration Evaluation Standard \u2014 Complete Guide\",\n \"description\": \"Comprehensive guide to ISO 20816-1 standard for measuring and evaluating machine vibration. Covers evaluation zones A-D, dual criteria (absolute limits and change from baseline), casing and shaft measurement, machine groups, alarm setpoints, and practical application.\",\n \"author\": {\n \"@type\": \"Organization\",\n \"name\": \"Vibromera\",\n \"url\": \"https:\/\/vibromera.eu\/\"\n },\n \"publisher\": {\n \"@type\": \"Organization\",\n \"name\": \"Vibromera\",\n \"url\": \"https:\/\/vibromera.eu\/\"\n },\n \"mainEntityOfPage\": \"https:\/\/vibromera.eu\/glossary\/iso-20816-1\/\",\n \"datePublished\": \"2025-03-10\",\n \"dateModified\": \"2026-02-09\",\n \"inLanguage\": \"en\",\n \"proficiencyLevel\": \"Beginner\",\n \"about\": [\n {\n \"@type\": \"Thing\",\n \"name\": \"ISO 20816-1\"\n },\n {\n \"@type\": \"Thing\",\n \"name\": \"Machine Vibration Evaluation\"\n },\n {\n \"@type\": \"Thing\",\n \"name\": \"Vibration Severity Assessment\"\n }\n ]\n },\n {\n \"@type\": \"FAQPage\",\n \"@id\": \"https:\/\/vibromera.eu\/glossary\/iso-20816-1\/#faq\",\n \"mainEntity\": [\n {\n \"@type\": \"Question\",\n \"name\": \"What is the difference between ISO 20816 and ISO 10816?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"ISO 20816 replaces and unifies two older standards: ISO 10816 (casing vibration on non-rotating parts) and ISO 7919 (shaft vibration on rotating parts). ISO 20816-1 combines both measurement philosophies into one framework. The zone boundary values from ISO 10816-3 are carried forward into ISO 20816-3 with minor updates.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What are the four vibration evaluation zones in ISO 20816?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Zone A (green): newly commissioned machines in good condition. Zone B (yellow): acceptable for unrestricted long-term operation. Zone C (orange): unsatisfactory for long-term operation, schedule corrective action. Zone D (red): severe enough to cause damage, take immediate action.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What vibration units does ISO 20816-1 use?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"For casing (bearing housing) measurements: broadband RMS velocity in mm\/s, typically over 10-1000 Hz range. For shaft measurements: peak-to-peak displacement in micrometers (\u03bcm), measured with proximity probes relative to the bearing housing.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What are the two evaluation criteria in ISO 20816?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Criterion 1: Absolute magnitude \u2014 compare measured vibration against fixed zone boundaries. Criterion 2: Change from baseline \u2014 evaluate change relative to established reference. Both must be used together. A significant change from baseline can indicate a developing fault even if the absolute value is still in Zone A or B.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What are the machine groups in ISO 20816-3?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Group 1: Large machines above 300 kW on rigid foundations. Group 2: Medium machines 15-300 kW on rigid foundations. Group 3: Large machines above 300 kW on flexible foundations. Group 4: Medium machines 15-300 kW on flexible foundations or special machines.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"Can I use the Balanset-1A for ISO 20816 vibration assessment?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Yes. The Balanset-1A measures broadband RMS velocity (the parameter specified by ISO 20816 for casing vibration) in its Vibrometer mode (F5). You can compare the measured value directly against the zone boundaries from ISO 20816-3 to assess machine condition.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"What is the frequency range for ISO 20816 measurements?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"For casing vibration: 10-1000 Hz for most general machines, or 2-1000 Hz for low-speed machines. For shaft displacement: typically 1\u00d7 RPM and below for relative measurements. The exact range depends on the machine type and the specific part of the standard.\"\n }\n },\n {\n \"@type\": \"Question\",\n \"name\": \"How do I set alarm and trip levels using ISO 20816?\",\n \"acceptedAnswer\": {\n \"@type\": \"Answer\",\n \"text\": \"Alert (alarm) is typically set at the Zone B\/C boundary. Danger (trip) is set at the Zone C\/D boundary. Additionally, a relative alert can be set when vibration increases by a factor of 2.0-2.5\u00d7 from the established baseline, even if absolute levels are still acceptable.\"\n }\n }\n ]\n },\n {\n \"@type\": \"BreadcrumbList\",\n \"itemListElement\": [\n {\n \"@type\": \"ListItem\",\n \"position\": 1,\n \"name\": \"Home\",\n \"item\": \"https:\/\/vibromera.eu\/\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 2,\n \"name\": \"Glossary\",\n \"item\": \"https:\/\/vibromera.eu\/glossary\/\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 3,\n \"name\": \"ISO 20816-1\"\n }\n ]\n },\n {\n \"@type\": \"DefinedTermSet\",\n \"name\": \"ISO 20816 Terminology\",\n \"hasDefinedTerm\": [\n {\n \"@type\": \"DefinedTerm\",\n \"name\": \"Evaluation Zone\",\n \"description\": \"One of four severity classifications (A, B, C, D) for machine vibration levels, ranging from newly commissioned condition to damage-causing severity.\"\n },\n {\n \"@type\": \"DefinedTerm\",\n \"name\": \"Criterion 1 (Absolute Limits)\",\n \"description\": \"Evaluation method comparing measured vibration magnitude against fixed zone boundaries established by the standard for specific machine types.\"\n },\n {\n \"@type\": \"DefinedTerm\",\n \"name\": \"Criterion 2 (Change from Baseline)\",\n \"description\": \"Evaluation method assessing the change in vibration from an established reference condition, used to detect developing faults regardless of absolute level.\"\n },\n {\n \"@type\": \"DefinedTerm\",\n \"name\": \"Broadband RMS Velocity\",\n \"description\": \"Root Mean Square of vibration velocity measured over a defined frequency range (typically 10-1000 Hz), the primary metric for casing vibration assessment per ISO 20816.\"\n },\n {\n \"@type\": \"DefinedTerm\",\n \"name\": \"Peak-to-Peak Displacement\",\n \"description\": \"Total shaft orbit diameter measured by proximity probes, the primary metric for shaft vibration assessment per ISO 20816, expressed in micrometers.\"\n },\n {\n \"@type\": \"DefinedTerm\",\n \"name\": \"Alert Setpoint\",\n \"description\": \"Vibration threshold that triggers increased monitoring and investigation. Typically set at Zone B\/C boundary or at 2.0-2.5\u00d7 baseline value.\"\n },\n {\n \"@type\": \"DefinedTerm\",\n \"name\": \"Trip Setpoint\",\n \"description\": \"Vibration threshold that triggers automatic machine shutdown to prevent damage. Typically set at Zone C\/D boundary.\"\n }\n ]\n },\n {\n \"@type\": \"Product\",\n \"name\": \"Balanset-1A\",\n \"description\": \"Professional portable two-channel vibration analyzer and dynamic balancer with ISO 20816 severity assessment capability\",\n \"brand\": {\n \"@type\": \"Brand\",\n \"name\": \"Vibromera\"\n },\n \"url\": \"https:\/\/vibromera.eu\/product\/balanset-1\/\",\n \"offers\": {\n \"@type\": \"Offer\",\n \"url\": \"https:\/\/vibromera.eu\/product\/balanset-1\/\",\n \"priceCurrency\": \"EUR\",\n \"availability\": \"https:\/\/schema.org\/InStock\",\n \"price\": \"1975.00\",\n \"priceValidUntil\": \"2027-12-31\"\n }\n },\n {\n \"@type\": \"ItemList\",\n \"name\": \"ISO 20816-1 Guide Contents\",\n \"numberOfItems\": 10,\n \"itemListElement\": [\n {\n \"@type\": \"ListItem\",\n \"position\": 1,\n \"name\": \"Interactive Calculators\"\n },\n {\n \"@type\": \"ListItem\",\n \"position\": 2,\n \"name\": \"What Is ISO 20816-1\"\n },\n {\n \"@type\": \"ListItem\",\n 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a{color:var(--blue);text-decoration:none;font-weight:500}.page-footer p{font-size:14px;color:var(--text-muted)}\n@media(max-width:1200px){.container,.hero-inner,.quick-nav-inner{padding:0 32px}.content-layout{grid-template-columns:1fr 260px;gap:32px}.calc-grid{grid-template-columns:1fr 1fr}.related-grid{grid-template-columns:repeat(2,1fr)}}\n@media(max-width:960px){.content-layout{grid-template-columns:1fr}.toc-sidebar{position:static;order:-1}.calc-grid{grid-template-columns:1fr}}\n@media(max-width:768px){.container,.hero-inner,.quick-nav-inner{padding:0 20px}.hero{padding:36px 0 32px}.hero h1{font-size:28px}.hero .subtitle{font-size:16px}.article-content h2{font-size:24px}.calc-row{grid-template-columns:1fr}.result-grid{grid-template-columns:1fr}table{font-size:13px}table th,table td{padding:8px 10px}.formula-box{padding:18px 20px}.formula-box .formula-main{font-size:16px}.shop-cta h2{font-size:24px}.related-grid{grid-template-columns:1fr}}\n@media(max-width:480px){.hero h1{font-size:24px}.quick-nav a{padding:12px 12px;font-size:13px}}\n@media print{.quick-nav,.shop-cta,.toc-sidebar,.calc-panel{display:none}}\n<\/style>\n<\/head>\n<body>\n\n<header class=\"hero\">\n<div class=\"hero-inner\">\n<div class=\"breadcrumb\"><a href=\"https:\/\/vibromera.eu\/\">Home<\/a> \u2192 <a href=\"https:\/\/vibromera.eu\/glossary\/\">Glossary<\/a> \u2192 ISO 20816-1<\/div>\n<h1>ISO 20816-1 \u2014 <span>Machine Vibration<\/span> Evaluation Standard<\/h1>\n<div class=\"canon-badge\"><span style=\"font-size:14px;\">\ud83d\udccc<\/span> Canonical Reference Article \u2014 vibromera.eu<\/div>\n<div class=\"subtitle\">Complete guide to the modern unified standard for measuring and evaluating machinery vibration. Replaces ISO 10816-1 and ISO 7919-1. Interactive zone checker, alarm calculator, and vibration unit converter.<\/div>\n<\/div>\n<\/header>\n\n<nav class=\"quick-nav\"><div class=\"quick-nav-inner\">\n<a href=\"#calculators\">\ud83e\uddee Calculators<\/a>\n<a href=\"#what-is\">\ud83d\udcc4 What Is ISO 20816<\/a>\n<a href=\"#series\">\ud83d\udcda 20816 Series<\/a>\n<a href=\"#measurement\">\ud83d\udccf Measurement Types<\/a>\n<a href=\"#zones\">\ud83d\udea6 Zones A\u2013D<\/a>\n<a href=\"#criteria\">\ud83d\udcca Dual Criteria<\/a>\n<a href=\"#groups\">\ud83c\udfed Machine Groups<\/a>\n<a href=\"#alarms\">\ud83d\udd14 Alarm & Trip<\/a>\n<a href=\"#acceptance\">\u2705 Acceptance Testing<\/a>\n<a href=\"#migration\">\ud83d\udd04 ISO 10816 Migration<\/a>\n<a href=\"#balanset\">\ud83d\udd27 Balanset-1A<\/a>\n<a href=\"#faq\">\u2753 FAQ<\/a>\n<\/div><\/nav>\n\n\n<section class=\"section-bg\" id=\"calculators\">\n<div class=\"container\">\n<div class=\"section-header\">\n<h2>Vibration Assessment Tools<\/h2>\n<p>ISO 20816-3 zone checker, alarm setpoint calculator, and vibration unit converter<\/p>\n<\/div>\n<div class=\"calc-grid\">\n\n\n<div class=\"calc-panel\">\n<div class=\"calc-header\">\ud83d\udea6 ISO 20816-3 Casing Vibration Zone Checker<\/div>\n<div class=\"calc-body\">\n<div class=\"calc-form\">\n<div>\n<label>Machine Group<\/label>\n<select id=\"zc-group\" onchange=\"calcZone()\">\n<option value=\"1\">Group 1 \u2014 Large rigid foundation (>300 kW)<\/option>\n<option value=\"2\" selected>Group 2 \u2014 Medium rigid foundation (15\u2013300 kW)<\/option>\n<option value=\"3\">Group 3 \u2014 Large flexible foundation (>300 kW)<\/option>\n<option value=\"4\">Group 4 \u2014 Medium flexible\/special (15\u2013300 kW)<\/option>\n<\/select>\n<\/div>\n<div>\n<label>Measured RMS Velocity (mm\/s)<\/label>\n<input type=\"number\" id=\"zc-vel\" value=\"3.2\" step=\"0.1\" oninput=\"calcZone()\">\n<\/div>\n<button class=\"calc-btn\" onclick=\"calcZone()\">Check Zone<\/button>\n<\/div>\n<div class=\"severity-bar\">\n<div class=\"sev-zone sev-a\">A<\/div><div class=\"sev-zone sev-b\">B<\/div><div class=\"sev-zone sev-c\">C<\/div><div class=\"sev-zone sev-d\">D<\/div>\n<\/div>\n<div class=\"results-panel\" id=\"zc-results\">\n<div class=\"result-grid\">\n<div class=\"result-card primary\">\n<div class=\"r-label\">Assessment<\/div>\n<div class=\"r-value\" id=\"zc-zone\">\u2014<\/div>\n<div class=\"r-unit\" id=\"zc-action\">\u2014<\/div>\n<\/div>\n<div class=\"result-card\"><div class=\"r-label\">A\/B Boundary<\/div><div class=\"r-value\" id=\"zc-ab\">\u2014<\/div><div class=\"r-unit\">mm\/s<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">B\/C Boundary<\/div><div class=\"r-value\" id=\"zc-bc\">\u2014<\/div><div class=\"r-unit\">mm\/s (Alert)<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">C\/D Boundary<\/div><div class=\"r-value\" id=\"zc-cd\">\u2014<\/div><div class=\"r-unit\">mm\/s (Trip)<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Margin to Alert<\/div><div class=\"r-value\" id=\"zc-margin\">\u2014<\/div><div class=\"r-unit\">mm\/s remaining<\/div><\/div>\n<\/div>\n<div class=\"severity-result\" id=\"zc-severity\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"calc-panel\">\n<div class=\"calc-header\">\ud83d\udd14 Alarm Setpoint Calculator<\/div>\n<div class=\"calc-body\">\n<div class=\"calc-form\">\n<div><label>Baseline Vibration (mm\/s RMS)<\/label><input type=\"number\" id=\"al-base\" value=\"1.5\" step=\"0.1\" oninput=\"calcAlarm()\"><\/div>\n<div class=\"calc-row\">\n<div><label>Alert Multiplier<\/label>\n<select id=\"al-mult\" onchange=\"calcAlarm()\">\n<option value=\"2.0\">2.0\u00d7 (conservative)<\/option>\n<option value=\"2.5\" selected>2.5\u00d7 (standard)<\/option>\n<option value=\"3.0\">3.0\u00d7 (relaxed)<\/option>\n<\/select><\/div>\n<div><label>Machine Group<\/label>\n<select id=\"al-group\" onchange=\"calcAlarm()\">\n<option value=\"1\">Group 1<\/option>\n<option value=\"2\" selected>Group 2<\/option>\n<option value=\"3\">Group 3<\/option>\n<option value=\"4\">Group 4<\/option>\n<\/select><\/div>\n<\/div>\n<button class=\"calc-btn\" onclick=\"calcAlarm()\">Calculate Setpoints<\/button>\n<\/div>\n<div class=\"results-panel\" id=\"al-results\">\n<div class=\"result-grid\">\n<div class=\"result-card\"><div class=\"r-label\">Relative Alert (Criterion 2)<\/div><div class=\"r-value\" id=\"al-rel-alert\">\u2014<\/div><div class=\"r-unit\">mm\/s (baseline \u00d7 multiplier)<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Absolute Alert (B\/C boundary)<\/div><div class=\"r-value\" id=\"al-abs-alert\">\u2014<\/div><div class=\"r-unit\">mm\/s (Criterion 1)<\/div><\/div>\n<div class=\"result-card primary\"><div class=\"r-label\">Recommended Alert Setpoint<\/div><div class=\"r-value\" id=\"al-alert\">\u2014<\/div><div class=\"r-unit\">mm\/s \u2014 whichever is LOWER<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Trip Setpoint (C\/D boundary)<\/div><div class=\"r-value\" id=\"al-trip\">\u2014<\/div><div class=\"r-unit\">mm\/s<\/div><\/div>\n<\/div>\n<div style=\"margin-top:12px;font-size:13px;color:var(--text-muted);line-height:1.5;\">\n<strong>Logic:<\/strong> Alert = whichever is lower between the relative (baseline \u00d7 multiplier) and absolute (B\/C boundary) value. This ensures early warning regardless of which criterion triggers first. Trip is always the C\/D boundary.\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"calc-panel\">\n<div class=\"calc-header\">\ud83d\udd04 Vibration Unit Converter<\/div>\n<div class=\"calc-body\">\n<div class=\"calc-form\">\n<div class=\"calc-row\">\n<div><label>Value<\/label><input type=\"number\" id=\"uc-val\" value=\"4.5\" step=\"0.01\" oninput=\"calcUnits()\"><\/div>\n<div><label>Input Unit<\/label>\n<select id=\"uc-from\" onchange=\"calcUnits()\">\n<option value=\"vel\" selected>mm\/s RMS (velocity)<\/option>\n<option value=\"disp\">\u03bcm peak-peak (displacement)<\/option>\n<option value=\"acc\">m\/s\u00b2 RMS (acceleration)<\/option>\n<option value=\"g\">g RMS (acceleration)<\/option>\n<option value=\"ips\">in\/s peak (IPS)<\/option>\n<option value=\"mil\">mils peak-peak<\/option>\n<\/select><\/div>\n<\/div>\n<div><label>Vibration Frequency (Hz) \u2014 required for conversion between parameters<\/label><input type=\"number\" id=\"uc-freq\" value=\"25\" step=\"0.1\" oninput=\"calcUnits()\"><\/div>\n<button class=\"calc-btn\" onclick=\"calcUnits()\">Convert<\/button>\n<\/div>\n<div class=\"results-panel\" id=\"uc-results\">\n<div class=\"result-grid\">\n<div class=\"result-card\"><div class=\"r-label\">Velocity (RMS)<\/div><div class=\"r-value\" id=\"uc-vel\">\u2014<\/div><div class=\"r-unit\">mm\/s<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Displacement (pk-pk)<\/div><div class=\"r-value\" id=\"uc-disp\">\u2014<\/div><div class=\"r-unit\">\u03bcm<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Acceleration (RMS)<\/div><div class=\"r-value\" id=\"uc-acc\">\u2014<\/div><div class=\"r-unit\">m\/s\u00b2<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Acceleration (RMS)<\/div><div class=\"r-value\" id=\"uc-g\">\u2014<\/div><div class=\"r-unit\">g<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">IPS (peak)<\/div><div class=\"r-value\" id=\"uc-ips\">\u2014<\/div><div class=\"r-unit\">in\/s peak<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">Mils (pk-pk)<\/div><div class=\"r-value\" id=\"uc-mil\">\u2014<\/div><div class=\"r-unit\">mils pk-pk<\/div><\/div>\n<\/div>\n<div style=\"margin-top:12px;font-size:13px;color:var(--text-muted);line-height:1.5;\">\n<strong>Note:<\/strong> Conversions between displacement, velocity, and acceleration assume <em>sinusoidal<\/em> vibration at the specified frequency. Real vibration contains multiple frequencies \u2014 use spectrum analysis for precision. IPS peak = mm\/s RMS \u00d7 0.0557. Mils pk-pk = \u03bcm pk-pk \/ 25.4.\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"calc-panel\">\n<div class=\"calc-header\">\ud83d\udce1 Shaft Displacement Zone Checker (ISO 7919 \/ 20816)<\/div>\n<div class=\"calc-body\">\n<div class=\"calc-form\">\n<div><label>Machine Type<\/label>\n<select id=\"sd-type\" onchange=\"calcShaft()\">\n<option value=\"turbo\" selected>Steam\/gas turbine, turbo-generator<\/option>\n<option value=\"hydro\">Hydraulic turbine\/generator (vertical)<\/option>\n<option value=\"pump-gen\">Pumps, compressors (general)<\/option>\n<\/select><\/div>\n<div class=\"calc-row\">\n<div><label>Shaft Speed (RPM)<\/label><input type=\"number\" id=\"sd-rpm\" value=\"3000\" oninput=\"calcShaft()\"><\/div>\n<div><label>Measured Displacement (\u03bcm pk-pk)<\/label><input type=\"number\" id=\"sd-disp\" value=\"85\" step=\"1\" oninput=\"calcShaft()\"><\/div>\n<\/div>\n<button class=\"calc-btn\" onclick=\"calcShaft()\">Check Zone<\/button>\n<\/div>\n<div class=\"severity-bar\">\n<div class=\"sev-zone sev-a\">A<\/div><div class=\"sev-zone sev-b\">B<\/div><div class=\"sev-zone sev-c\">C<\/div><div class=\"sev-zone sev-d\">D<\/div>\n<\/div>\n<div class=\"results-panel\" id=\"sd-results\">\n<div class=\"result-grid\">\n<div class=\"result-card primary\"><div class=\"r-label\">Assessment<\/div><div class=\"r-value\" id=\"sd-zone\">\u2014<\/div><div class=\"r-unit\" id=\"sd-action\">\u2014<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">A\/B Boundary<\/div><div class=\"r-value\" id=\"sd-ab\">\u2014<\/div><div class=\"r-unit\">\u03bcm pk-pk<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">B\/C (Alert)<\/div><div class=\"r-value\" id=\"sd-bc\">\u2014<\/div><div class=\"r-unit\">\u03bcm pk-pk<\/div><\/div>\n<div class=\"result-card\"><div class=\"r-label\">C\/D (Trip)<\/div><div class=\"r-value\" id=\"sd-cd\">\u2014<\/div><div class=\"r-unit\">\u03bcm pk-pk<\/div><\/div>\n<\/div>\n<div class=\"severity-result\" id=\"sd-severity\"><\/div>\n<div style=\"margin-top:12px;font-size:13px;color:var(--text-muted);line-height:1.5;\">\nZone boundaries for turbo-machinery are speed-dependent: limits = k \u00d7 \u221a(9000\/RPM). Values shown are approximate per ISO 7919-2 \/ ISO 20816-2.\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n<\/div>\n<\/div>\n<\/section>\n\n\n<main class=\"main-content\">\n<div class=\"container\">\n<div class=\"content-layout\">\n<article class=\"article-content\">\n\n<h2 id=\"what-is\">What Is ISO 20816-1?<\/h2>\n\n<p><strong>ISO 20816-1:2016<\/strong> (full title: \"Mechanical vibration \u2014 Measurement and evaluation of machine vibration \u2014 Part 1: General guidelines\") is the current international standard providing the framework for how machinery vibration should be measured and evaluated. It was published in 2016 and replaces two older foundational standards that had been in use since the 1990s.<\/p>\n\n<p>The most significant change is the <strong>unification<\/strong> of two previously separate measurement philosophies into a single, cohesive document:<\/p>\n<ul>\n<li><strong><a href=\"https:\/\/vibromera.eu\/glossary\/iso-10816-1\/\">ISO 10816-1<\/a><\/strong> \u2014 covered vibration measured on <em>non-rotating parts<\/em> (bearing housings, machine casing) using seismic sensors (accelerometers).<\/li>\n<li><strong>ISO 7919-1<\/strong> \u2014 covered vibration measured on <em>rotating shafts<\/em> using non-contact proximity probes.<\/li>\n<\/ul>\n\n<p>ISO 20816-1 combines both approaches into one framework, recognizing that comprehensive machine assessment often requires both types of measurement. A machine might have acceptable casing vibration but dangerous shaft movement (indicating a rotor-dynamic problem), or vice versa (indicating a structural\/foundation issue). Only by evaluating both can you get the full picture.<\/p>\n\n<div class=\"info-box\">\n<div class=\"box-title\">\ud83d\udca1 Key Takeaway<\/div>\n<p>ISO 20816-1 is a <em>general guidelines<\/em> document. It defines the <strong>concepts, methodology, and evaluation framework<\/strong> (zones, criteria, measurement types) but does NOT contain specific numerical limits. The actual zone boundary values for specific machine types are in the other parts of the series (ISO 20816-2 through 20816-9). For most industrial machines, <strong>ISO 20816-3<\/strong> provides the numbers.<\/p>\n<\/div>\n\n<h3>What the Standard Covers<\/h3>\n<ol>\n<li><strong>Scope and measurement types<\/strong> \u2014 defines both casing and shaft vibration measurement methodologies<\/li>\n<li><strong>Instrumentation requirements<\/strong> \u2014 sensor types, frequency ranges, calibration, mounting standards<\/li>\n<li><strong>Evaluation criteria<\/strong> \u2014 the two-criterion approach (absolute limits + change from baseline)<\/li>\n<li><strong>Evaluation zones<\/strong> \u2014 the four-zone classification system (A, B, C, D)<\/li>\n<li><strong>Combined assessment and acceptance<\/strong> \u2014 how to use both measurement types together, acceptance testing vs. operational monitoring<\/li>\n<\/ol>\n\n<h2 id=\"series\">The Complete ISO 20816 Series<\/h2>\n\n<p>ISO 20816 is a multi-part standard. Part 1 provides the general framework; other parts provide specific numerical limits for different machine categories.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">ISO 20816 Series \u2014 All Parts<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Part<\/th><th>Title \/ Scope<\/th><th>Replaces<\/th><th>Status<\/th><\/tr><\/thead>\n<tbody>\n<tr><td class=\"mono\"><strong>20816-1<\/strong><\/td><td>General guidelines<\/td><td>ISO 10816-1 + ISO 7919-1<\/td><td>Published 2016<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-2<\/strong><\/td><td>Land-based gas turbines, steam turbines, generators >40 MW<\/td><td>ISO 10816-2 + ISO 7919-2<\/td><td>Published 2017<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-3<\/strong><\/td><td>Industrial machines with power >15 kW and speed 120\u201315000 RPM<\/td><td>ISO 10816-3 + ISO 7919-3<\/td><td>Published 2022<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-4<\/strong><\/td><td>Gas turbine driven sets (excluding aircraft derivatives)<\/td><td>ISO 10816-4 + ISO 7919-4<\/td><td>Published 2018<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-5<\/strong><\/td><td>Hydraulic machine sets including pumps >15 kW<\/td><td>ISO 10816-5 + ISO 7919-5<\/td><td>Published 2018<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-6<\/strong><\/td><td>Reciprocating machines >100 kW<\/td><td>ISO 10816-6<\/td><td>Published 2016<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-7<\/strong><\/td><td>Rotodynamic pumps (industrial, including measurements on rotating shafts)<\/td><td>ISO 10816-7<\/td><td>Published 2017<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-8<\/strong><\/td><td>Reciprocating compressor systems<\/td><td>ISO 10816-8<\/td><td>Published 2018<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-9<\/strong><\/td><td>Gear units<\/td><td>New (no predecessor)<\/td><td>Published 2020<\/td><\/tr>\n<tr><td class=\"mono\"><strong>20816-21<\/strong><\/td><td>Onshore wind turbines (horizontal axis, \u2265100 kW)<\/td><td>New<\/td><td>Published 2015<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box warning\">\n<div class=\"box-title\">\u26a0\ufe0f ISO 10816-3 vs. ISO 20816-3<\/div>\n<p>ISO 10816-3:2009 was formally withdrawn when ISO 20816-3:2022 was published. However, ISO 10816-3 zone boundaries remain widely used in industry because they are well-established and most monitoring systems are configured with them. The casing vibration limits in ISO 20816-3 are very similar (in many cases identical) to ISO 10816-3. If your existing monitoring program uses ISO 10816-3 values, there is no urgent need to change \u2014 but new installations should reference ISO 20816-3.<\/p>\n<\/div>\n\n<h2 id=\"measurement\">Measurement Types<\/h2>\n\n<p>ISO 20816-1 formally unifies two fundamentally different measurement approaches. Understanding the distinction is critical for correct application.<\/p>\n\n<h3>Casing Vibration (Non-Rotating Parts)<\/h3>\n\n<ul>\n<li><strong>What:<\/strong> Vibration of the stationary machine structure \u2014 bearing housings, pedestals, frames, casing.<\/li>\n<li><strong>Sensor:<\/strong> Seismic transducers \u2014 piezoelectric accelerometers (most common) or velocity transducers \u2014 mounted on the bearing housing per <a href=\"https:\/\/vibromera.eu\/glossary\/iso-5348\/\">ISO 5348<\/a>.<\/li>\n<li><strong>Parameter:<\/strong> <strong>Broadband RMS velocity<\/strong> in <strong>mm\/s<\/strong> (or in\/s in some regions).<\/li>\n<li><strong>Frequency range:<\/strong> 10\u20131000 Hz standard; 2\u20131000 Hz for low-speed machines (<120 RPM).<\/li>\n<li><strong>What it tells you:<\/strong> The vibration energy being transmitted into the machine structure. Reflects the forces acting on bearings and the structural response. Directly correlates with bearing fatigue and structural damage risk.<\/li>\n<li><strong>Equipment:<\/strong> The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> measures broadband RMS velocity in its Vibrometer mode (F5), making it directly suitable for ISO 20816 casing assessment.<\/li>\n<\/ul>\n\n<h3>Shaft Vibration (Rotating Parts)<\/h3>\n\n<ul>\n<li><strong>What:<\/strong> Dynamic displacement of the shaft relative to the bearing housing \u2014 how much the shaft actually moves within its bearing clearance.<\/li>\n<li><strong>Sensor:<\/strong> Non-contact eddy-current proximity probes, typically installed in orthogonal pairs (X-Y) at each bearing per API 670.<\/li>\n<li><strong>Parameter:<\/strong> <strong>Peak-to-peak displacement<\/strong> in <strong>\u03bcm<\/strong> (micrometers) or mils (1 mil = 25.4 \u03bcm).<\/li>\n<li><strong>Frequency range:<\/strong> Primarily shaft synchronous (1\u00d7) and sub-synchronous components.<\/li>\n<li><strong>What it tells you:<\/strong> The actual rotor dynamic behavior \u2014 orbit shape, whirl direction, rub contact. Critical for detecting shaft bow, oil whirl, seal contact, and misalignment that may not transfer efficiently to the casing.<\/li>\n<li><strong>Equipment:<\/strong> Permanently installed proximity probes (not typically portable instruments). Primarily used on large turbo-machinery with fluid-film (journal) bearings.<\/li>\n<\/ul>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Casing vs. Shaft Vibration \u2014 Comparison<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Aspect<\/th><th>Casing (Non-Rotating Parts)<\/th><th>Shaft (Rotating Parts)<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Sensor<\/strong><\/td><td>Accelerometer \/ velocity transducer<\/td><td>Proximity probe (eddy current)<\/td><\/tr>\n<tr><td><strong>Mounting<\/strong><\/td><td>On bearing housing (external)<\/td><td>Inside bearing housing (internal)<\/td><\/tr>\n<tr><td><strong>Parameter<\/strong><\/td><td>RMS velocity (mm\/s)<\/td><td>Peak-to-peak displacement (\u03bcm)<\/td><\/tr>\n<tr><td><strong>Frequency range<\/strong><\/td><td>10\u20131000 Hz (broadband)<\/td><td>Sub-synchronous to 1\u00d7 RPM<\/td><\/tr>\n<tr><td><strong>Detects best<\/strong><\/td><td>Unbalance, misalignment, looseness, bearing defects, structural resonance<\/td><td>Shaft bow, oil whirl\/whip, seal rub, rotor instability, journal bearing condition<\/td><\/tr>\n<tr><td><strong>Typical machines<\/strong><\/td><td>All \u2014 fans, pumps, motors, compressors, general industrial<\/td><td>Large turbo-machinery with journal bearings<\/td><\/tr>\n<tr><td><strong>Portable measurement<\/strong><\/td><td>Yes (Balanset-1A, portable analyzers)<\/td><td>Permanently installed probes only<\/td><\/tr>\n<tr><td><strong>Standard reference<\/strong><\/td><td>Formerly ISO 10816, now ISO 20816<\/td><td>Formerly ISO 7919, now ISO 20816<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box success\">\n<div class=\"box-title\">\u2705 Why Both Matter<\/div>\n<p>A machine can have <strong>low casing vibration but high shaft displacement<\/strong> \u2014 the forces aren't being transmitted to the structure (e.g., very stiff bearing housing), but the shaft is moving dangerously inside the bearing clearance. Conversely, <strong>high casing vibration with normal shaft displacement<\/strong> suggests a structural problem (loose foundation, resonance) rather than a rotor-dynamic issue. ISO 20816-1 recommends evaluating both wherever possible for a complete diagnosis.<\/p>\n<\/div>\n\n<h3>Instrumentation Requirements<\/h3>\n<p>The standard specifies that the entire measurement chain \u2014 transducer, cabling, signal conditioning, and analyzer \u2014 must be calibrated and capable of accurately measuring over the required frequency range. Key references:<\/p>\n<ul>\n<li><strong>Accelerometer mounting:<\/strong> Per <a href=\"https:\/\/vibromera.eu\/glossary\/iso-5348\/\">ISO 5348<\/a> \u2014 stud mount preferred, magnetic acceptable for routine monitoring, adhesive for permanent installation.<\/li>\n<li><strong>Proximity probe installation:<\/strong> Per API 670 \u2014 probe gap, target surface finish, orthogonal pair orientation, and cable routing requirements.<\/li>\n<li><strong>Calibration:<\/strong> Regular calibration of the entire chain against traceable standards. The Balanset-1A ships factory-calibrated and can be verified against known vibration sources.<\/li>\n<\/ul>\n\n<h2 id=\"zones\">Evaluation Zones A, B, C, D<\/h2>\n\n<p>The four-zone system is the most recognized feature of the ISO vibration standards. It provides a universal, color-coded framework for classifying vibration severity and determining appropriate action.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Zone Definitions and Required Actions<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th style=\"width:8%\">Zone<\/th><th style=\"width:12%\">Color<\/th><th>Machine Condition<\/th><th>Required Action<\/th><\/tr><\/thead>\n<tbody>\n<tr><td class=\"zone-a\">A<\/td><td><span class=\"zone-badge za\">GREEN<\/span><\/td><td>Vibration of newly commissioned or reconditioned machines. Excellent condition.<\/td><td>Normal operation. Establish this as baseline for future trending. Target condition after maintenance.<\/td><\/tr>\n<tr><td class=\"zone-b\">B<\/td><td><span class=\"zone-badge zb\">YELLOW<\/span><\/td><td>Acceptable for unrestricted long-term operation. Normal wear-in condition.<\/td><td>Continue operation. Monitor trends \u2014 movement toward Zone C requires investigation. Acceptable for most operational machines.<\/td><\/tr>\n<tr><td class=\"zone-c\">C<\/td><td><span class=\"zone-badge zc\">ORANGE<\/span><\/td><td>Unsatisfactory for long-term continuous operation. Developing fault or deteriorating condition.<\/td><td><strong>Plan corrective action.<\/strong> Increase monitoring frequency. Investigate root cause. Schedule maintenance at next available opportunity.<\/td><\/tr>\n<tr><td class=\"zone-d\">D<\/td><td><span class=\"zone-badge zd\">RED<\/span><\/td><td>Sufficiently severe to cause damage. Risk of catastrophic failure.<\/td><td><strong>Take immediate action.<\/strong> Consider emergency shutdown. Do not continue operation \u2014 damage to bearings, seals, and structural components is occurring.<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<h3>Zone Boundary Values \u2014 Casing Vibration (ISO 20816-3)<\/h3>\n\n<p>These are the specific numerical limits for <strong>broadband RMS velocity on bearing housings<\/strong>, applicable to industrial machines with power above 15 kW and speeds from 120 to 15,000 RPM. These values were originally established in ISO 10816-3 and are carried forward with minor updates in ISO 20816-3:2022.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">ISO 20816-3 \u2014 Casing Vibration Zone Boundaries (mm\/s RMS)<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Zone Boundary<\/th><th>Group 1<br>Large, rigid<br>(>300 kW)<\/th><th>Group 2<br>Medium, rigid<br>(15\u2013300 kW)<\/th><th>Group 3<br>Large, flexible<br>(>300 kW)<\/th><th>Group 4<br>Medium, flexible<br>(15\u2013300 kW)<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>A\/B<\/strong><\/td><td class=\"mono zone-a\">2.3<\/td><td class=\"mono zone-a\">1.4<\/td><td class=\"mono zone-a\">3.5<\/td><td class=\"mono zone-a\">2.3<\/td><\/tr>\n<tr><td><strong>B\/C<\/strong> (Alert)<\/td><td class=\"mono zone-b\">4.5<\/td><td class=\"mono zone-b\">2.8<\/td><td class=\"mono zone-b\">7.1<\/td><td class=\"mono zone-b\">4.5<\/td><\/tr>\n<tr><td><strong>C\/D<\/strong> (Trip)<\/td><td class=\"mono zone-c\">7.1<\/td><td class=\"mono zone-c\">7.1<\/td><td class=\"mono zone-c\">11.2<\/td><td class=\"mono zone-c\">11.2<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box\">\n<div class=\"box-title\">\ud83d\udca1 How to Read This Table<\/div>\n<p><strong>Example:<\/strong> You measure 3.2 mm\/s RMS on a 55 kW motor bolted to a concrete floor. This is Group 2 (medium power, rigid foundation). A\/B boundary = 1.4, B\/C = 2.8, C\/D = 7.1. Your reading of 3.2 exceeds 2.8 (B\/C) but is below 7.1 (C\/D), so the machine is in <strong>Zone C<\/strong> \u2014 schedule corrective action. Use the calculator above to check any value instantly.<\/p>\n<\/div>\n\n<h3>Zone Boundary Values \u2014 Shaft Displacement (ISO 20816-2)<\/h3>\n\n<p>For turbo-machinery with proximity probes, shaft displacement limits are speed-dependent. The standard uses a formula based on the square root of speed ratio.<\/p>\n\n<div class=\"formula-box\">\n<div class=\"formula-label\">Shaft Displacement Zone Boundaries (Turbo-machinery)<\/div>\n<div class=\"formula-main\">S<sub>boundary<\/sub> = k \u00d7 \u221a(9000 \/ n)<\/div>\n<div class=\"formula-note\">k = zone coefficient (varies by zone boundary and machine type) | n = shaft speed in RPM<br>Result in \u03bcm peak-to-peak | Higher speed \u2192 tighter limits<\/div>\n<\/div>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Approximate Shaft Displacement Boundaries \u2014 Large Steam\/Gas Turbines<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Zone Boundary<\/th><th>k Factor<\/th><th>@ 1500 RPM<\/th><th>@ 3000 RPM<\/th><th>@ 6000 RPM<\/th><th>@ 10000 RPM<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>A\/B<\/strong><\/td><td class=\"mono\">50<\/td><td class=\"mono zone-a\">122 \u03bcm<\/td><td class=\"mono zone-a\">87 \u03bcm<\/td><td class=\"mono zone-a\">61 \u03bcm<\/td><td class=\"mono zone-a\">47 \u03bcm<\/td><\/tr>\n<tr><td><strong>B\/C<\/strong> (Alert)<\/td><td class=\"mono\">80<\/td><td class=\"mono zone-b\">196 \u03bcm<\/td><td class=\"mono zone-b\">139 \u03bcm<\/td><td class=\"mono zone-b\">98 \u03bcm<\/td><td class=\"mono zone-b\">76 \u03bcm<\/td><\/tr>\n<tr><td><strong>C\/D<\/strong> (Trip)<\/td><td class=\"mono\">100<\/td><td class=\"mono zone-c\">245 \u03bcm<\/td><td class=\"mono zone-c\">173 \u03bcm<\/td><td class=\"mono zone-c\">122 \u03bcm<\/td><td class=\"mono zone-c\">95 \u03bcm<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<h2 id=\"criteria\">The Two Evaluation Criteria<\/h2>\n\n<p>ISO 20816-1 mandates that vibration assessment must consider <strong>both<\/strong> criteria simultaneously. Using only one gives an incomplete picture.<\/p>\n\n<h3>Criterion 1 \u2014 Absolute Magnitude<\/h3>\n\n<p>Compare the measured vibration value against the fixed zone boundaries from the applicable part of ISO 20816. This tells you the machine's condition relative to the general population of similar machines.<\/p>\n\n<ul>\n<li><strong>Use for:<\/strong> Acceptance testing of new\/repaired machines, baseline assessment, setting trip alarms, comparing machines across a fleet.<\/li>\n<li><strong>Limitation:<\/strong> A machine that has always been at 4.0 mm\/s (Zone B for Group 1) might be perfectly healthy \u2014 that's its normal operating level. Criterion 1 alone doesn't tell you if something has changed.<\/li>\n<\/ul>\n\n<h3>Criterion 2 \u2014 Change from Baseline<\/h3>\n\n<p>Compare the current vibration to an established reference (baseline) value. The baseline is typically measured after commissioning, after maintenance, or as a statistical average over a stable operating period.<\/p>\n\n<ul>\n<li><strong>Use for:<\/strong> Trend-based predictive maintenance, early fault detection, detecting deterioration regardless of absolute level.<\/li>\n<li><strong>Key insight:<\/strong> A significant <em>change<\/em> in vibration \u2014 even if the absolute value is still in Zone A or B \u2014 is often the <strong>earliest and most reliable indicator<\/strong> of a developing fault.<\/li>\n<\/ul>\n\n<div class=\"info-box warning\">\n<div class=\"box-title\">\u26a0\ufe0f Why Criterion 2 Is Often More Important<\/div>\n<p><strong>Scenario:<\/strong> A pump has a baseline of 1.0 mm\/s. Over three weeks, it rises to 2.5 mm\/s. By Criterion 1 (Group 2), 2.5 mm\/s is still in Zone B \u2014 \"acceptable.\" But by Criterion 2, the vibration has <em>increased 2.5\u00d7<\/em> from baseline, which is a significant change indicating a developing fault (possibly bearing wear or misalignment). Without Criterion 2, you would miss this alarm until the machine deteriorates further into Zone C or D.<\/p>\n<\/div>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Criterion 1 vs. Criterion 2 \u2014 Comparison<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Aspect<\/th><th>Criterion 1 \u2014 Absolute<\/th><th>Criterion 2 \u2014 Change from Baseline<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Reference<\/strong><\/td><td>Fixed zone boundaries from standard<\/td><td>Machine's own established baseline<\/td><\/tr>\n<tr><td><strong>Best for<\/strong><\/td><td>Acceptance testing, fleet comparison, trip alarms<\/td><td>Predictive maintenance, early fault detection, trending<\/td><\/tr>\n<tr><td><strong>Alert trigger<\/strong><\/td><td>Value exceeds B\/C boundary<\/td><td>Value exceeds 2.0\u20132.5\u00d7 baseline<\/td><\/tr>\n<tr><td><strong>Strength<\/strong><\/td><td>Objective, universal benchmark<\/td><td>Sensitive to change, machine-specific<\/td><\/tr>\n<tr><td><strong>Weakness<\/strong><\/td><td>Doesn't detect change from \"normal\" baseline<\/td><td>Requires established baseline; false alarms if baseline not stable<\/td><\/tr>\n<tr><td><strong>In ISO 20816<\/strong><\/td><td>Zone A\/B\/C\/D boundaries<\/td><td>\"Significant change\" threshold (standard recommends 2.0\u20132.5\u00d7)<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<h2 id=\"groups\">Machine Groups (ISO 20816-3)<\/h2>\n\n<p>ISO 20816-3 (and its predecessor ISO 10816-3) classifies machines into four groups based on <strong>power rating<\/strong> and <strong>foundation type<\/strong>. The zone boundaries are different for each group because larger machines on flexible foundations naturally have higher vibration than small machines on rigid foundations.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">Machine Group Classification<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Group<\/th><th>Power<\/th><th>Foundation<\/th><th>Typical Machines<\/th><th>A\/B<\/th><th>B\/C<\/th><th>C\/D<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Group 1<\/strong><\/td><td>>300 kW<\/td><td>Rigid<\/td><td>Large motors, generators, turbo-compressors on concrete base<\/td><td class=\"mono\">2.3<\/td><td class=\"mono\">4.5<\/td><td class=\"mono\">7.1<\/td><\/tr>\n<tr><td><strong>Group 2<\/strong><\/td><td>15\u2013300 kW<\/td><td>Rigid<\/td><td>Standard motors, pumps, fans on concrete or heavy steel frame<\/td><td class=\"mono\">1.4<\/td><td class=\"mono\">2.8<\/td><td class=\"mono\">7.1<\/td><\/tr>\n<tr><td><strong>Group 3<\/strong><\/td><td>>300 kW<\/td><td>Flexible<\/td><td>Large machines on steel structures, offshore platforms, upper floors<\/td><td class=\"mono\">3.5<\/td><td class=\"mono\">7.1<\/td><td class=\"mono\">11.2<\/td><\/tr>\n<tr><td><strong>Group 4<\/strong><\/td><td>15\u2013300 kW<\/td><td>Flexible<\/td><td>Medium machines on flexible frames, skid-mounted equipment<\/td><td class=\"mono\">2.3<\/td><td class=\"mono\">4.5<\/td><td class=\"mono\">11.2<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box\">\n<div class=\"box-title\">\ud83d\udca1 How to Determine the Foundation Type<\/div>\n<p><strong>Rigid foundation:<\/strong> The foundation's lowest natural frequency is well above the machine's operating speed. Practically: heavy concrete block, thick steel baseplate grouted to concrete. The foundation doesn't amplify or modify the machine's vibration.<br>\n<strong>Flexible foundation:<\/strong> The foundation has natural frequencies near or below the machine's operating speed. Practically: elevated steel platform, lightweight frame, spring-mounted skid, upper-floor installation. The foundation can amplify or attenuate vibration at certain frequencies.<\/p>\n<p>If in doubt, a simple test: measure vibration on the foundation surface next to the machine. If it's significantly lower than on the bearing housing, the foundation is likely rigid. If it's similar, the foundation may be acting as a flexible mount.<\/p>\n<\/div>\n\n<h2 id=\"alarms\">Alarm and Trip Setpoints<\/h2>\n\n<p>The practical application of ISO 20816 in monitoring systems requires setting <strong>Alert<\/strong> (alarm) and <strong>Danger<\/strong> (trip) setpoints. The standard provides guidance for both absolute and relative setpoints.<\/p>\n\n<h3>Absolute Setpoints (from Criterion 1)<\/h3>\n<ul>\n<li><strong>Alert<\/strong> = B\/C zone boundary value. When vibration exceeds this, increase monitoring, investigate root cause, plan corrective action.<\/li>\n<li><strong>Trip<\/strong> = C\/D zone boundary value. When vibration exceeds this, automatic shutdown (if available) or immediate manual action to prevent damage.<\/li>\n<\/ul>\n\n<h3>Relative Setpoints (from Criterion 2)<\/h3>\n<ul>\n<li><strong>Relative Alert<\/strong> = Baseline \u00d7 multiplier (typically 2.0\u20132.5\u00d7). A doubling or more of vibration from baseline indicates a developing fault.<\/li>\n<li>The <strong>effective alert setpoint<\/strong> should be whichever is <em>lower<\/em> between the absolute alert and the relative alert. This ensures the first criterion to be violated triggers the alarm.<\/li>\n<\/ul>\n\n<div class=\"info-box success\">\n<div class=\"box-title\">\u2705 Practical Setpoint Example<\/div>\n<p><strong>Machine:<\/strong> 75 kW motor, rigid foundation (Group 2). Baseline after commissioning: 1.2 mm\/s RMS.<br>\n<strong>Absolute alert<\/strong> (B\/C boundary, Group 2): 2.8 mm\/s<br>\n<strong>Relative alert<\/strong> (baseline \u00d7 2.5): 1.2 \u00d7 2.5 = 3.0 mm\/s<br>\n<strong>Effective alert<\/strong> = 2.8 mm\/s (lower of the two)<br>\n<strong>Trip<\/strong> (C\/D boundary): 7.1 mm\/s<br><br>\nIf this motor's vibration rises to 2.9 mm\/s, both criteria are violated \u2014 take action.<\/p>\n<\/div>\n\n<h2 id=\"acceptance\">Acceptance Testing vs. Operational Monitoring<\/h2>\n\n<p>ISO 20816-1 clearly distinguishes between two assessment contexts:<\/p>\n\n<h3>Acceptance Testing<\/h3>\n<p>Used when commissioning new machines or accepting machines after overhaul. The requirement is typically that vibration falls within <strong>Zone A or Zone B<\/strong>. This is a strict pass\/fail criterion \u2014 a new machine delivered in Zone C would normally be rejected.<\/p>\n<ul>\n<li>Measurement conditions must be tightly controlled (stable speed, full load, thermal equilibrium).<\/li>\n<li>Multiple readings at each measurement point.<\/li>\n<li>Results documented in a formal acceptance report.<\/li>\n<\/ul>\n\n<h3>Operational Monitoring<\/h3>\n<p>Used for ongoing condition assessment of in-service machines. The focus shifts from pass\/fail to <strong>trending and change detection<\/strong> (Criterion 2). Alert and trip setpoints are the primary tools.<\/p>\n<ul>\n<li>Portable route-based data collection (Balanset-1A) or permanent online monitoring.<\/li>\n<li>Consistent measurement points, conditions, and procedures for valid trend comparison.<\/li>\n<li>Action decisions based on both absolute zone and trend direction.<\/li>\n<\/ul>\n\n<h2 id=\"migration\">Migration from ISO 10816 to ISO 20816<\/h2>\n\n<p>Many facilities still reference ISO 10816 in their procedures, monitoring databases, and specifications. Here's what you need to know about the transition.<\/p>\n\n<div class=\"table-wrap\">\n<div class=\"table-title\">ISO 10816 \u2192 ISO 20816 Migration Map<\/div>\n<div class=\"table-scroll\"><table>\n<thead><tr><th>Old Standard<\/th><th>New Standard<\/th><th>Impact on Zone Values<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>ISO 10816-1:1995<\/td><td>ISO 20816-1:2016<\/td><td>General guidelines \u2014 no numerical values to change<\/td><\/tr>\n<tr><td>ISO 10816-2:2009<\/td><td>ISO 20816-2:2017<\/td><td>Some limits revised for modern turbo-machinery<\/td><\/tr>\n<tr><td>ISO 10816-3:2009<\/td><td>ISO 20816-3:2022<\/td><td>Casing velocity limits largely unchanged; shaft limits added<\/td><\/tr>\n<tr><td>ISO 10816-4:2009<\/td><td>ISO 20816-4:2018<\/td><td>Updated with shaft displacement criteria<\/td><\/tr>\n<tr><td>ISO 10816-5:2000<\/td><td>ISO 20816-5:2018<\/td><td>Revised for hydraulic machines<\/td><\/tr>\n<tr><td>ISO 10816-6:1995<\/td><td>ISO 20816-6:2016<\/td><td>Minor updates for reciprocating machines<\/td><\/tr>\n<tr><td>ISO 10816-7:2009<\/td><td>ISO 20816-7:2017<\/td><td>Updated pump evaluation criteria<\/td><\/tr>\n<tr><td>ISO 10816-8:2014<\/td><td>ISO 20816-8:2018<\/td><td>Reciprocating compressors \u2014 minor changes<\/td><\/tr>\n<tr><td>ISO 7919-1 through -5<\/td><td>Merged into 20816 series<\/td><td>Shaft displacement criteria now in same documents as casing<\/td><\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n\n<div class=\"info-box\">\n<div class=\"box-title\">\ud83d\udca1 Practical Migration Advice<\/div>\n<p><strong>For existing monitoring programs:<\/strong> If your systems are configured with ISO 10816-3 zone values, the casing vibration limits are essentially unchanged in ISO 20816-3. No urgent reconfiguration needed. Update reference numbers in documentation when convenient.<br>\n<strong>For new installations:<\/strong> Specify ISO 20816-3 (2022) as the reference standard. Consider adding shaft displacement monitoring where applicable (large machines with journal bearings).<br>\n<strong>For specifications and contracts:<\/strong> Update references from \"ISO 10816\" to \"ISO 20816\" in new purchase orders and maintenance contracts. Include both casing and shaft criteria where relevant.<\/p>\n<\/div>\n\n<h2 id=\"balanset\">Practical Application with Balanset-1A<\/h2>\n\n<p>The <a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\">Balanset-1A<\/a> portable vibration analyzer directly supports ISO 20816 casing vibration assessment through its built-in measurement modes.<\/p>\n\n<h4>Vibrometer Mode (F5)<\/h4>\n<p>Measures <strong>broadband RMS velocity<\/strong> \u2014 the exact parameter specified by ISO 20816 for casing vibration. Display shows:<\/p>\n<ul>\n<li><strong>V1s<\/strong> (overall vibration) \u2014 compare directly with zone boundaries<\/li>\n<li><strong>V1o<\/strong> (1\u00d7 RPM component) \u2014 indicates how much of the total vibration is from unbalance<\/li>\n<li>Both channels simultaneously \u2014 near and far bearing in one measurement<\/li>\n<\/ul>\n\n<h4>Spectrum Analyzer (F1 \/ F8)<\/h4>\n<p>Displays the FFT frequency spectrum, allowing you to identify the <em>source<\/em> of high vibration (unbalance at 1\u00d7, misalignment at 2\u00d7, bearing defects at characteristic frequencies). See the <a href=\"https:\/\/vibromera.eu\/glossary\/vibration-analysis\/\">Vibration Analysis Guide<\/a> for spectrum interpretation.<\/p>\n\n<h4>Balancing Mode<\/h4>\n<p>If vibration is diagnosed as unbalance (dominant 1\u00d7 RPM peak), the Balanset-1A can immediately proceed to field balancing to correct it \u2014 reducing vibration from Zone C or D back to Zone A or B. See the <a href=\"https:\/\/vibromera.eu\/glossary\/balancing\/\">Field Dynamic Balancing Guide<\/a> for the complete procedure.<\/p>\n\n<div class=\"action-box\">\n<p><strong>Workflow:<\/strong> Measure (F5) \u2192 Diagnose zone \u2192 If Zone C\/D and 1\u00d7 dominant \u2192 Analyze spectrum (F1) \u2192 Balance \u2192 Verify back in Zone A\/B.<\/p>\n<\/div>\n\n<h2 id=\"faq\">Frequently Asked Questions<\/h2>\n\n<p><strong>What is the difference between ISO 20816 and ISO 10816?<\/strong><\/p>\n<p>ISO 20816 replaces ISO 10816 by combining casing vibration (formerly ISO 10816) and shaft vibration (formerly ISO 7919) into a unified standard. The zone boundary values for casing vibration in ISO 20816-3 are very similar to those in ISO 10816-3. The main improvement is the integration of both measurement philosophies in one document.<\/p>\n\n<p><strong>Is ISO 10816 still valid?<\/strong><\/p>\n<p>ISO 10816 parts have been formally withdrawn as they are superseded by corresponding ISO 20816 parts. However, the vibration limits are widely embedded in existing monitoring systems and contracts. The numerical values for casing vibration are essentially unchanged, so existing ISO 10816-based programs remain technically valid in practice.<\/p>\n\n<p><strong>Which parameter should I measure \u2014 velocity or displacement?<\/strong><\/p>\n<p>For general industrial machines with rolling-element bearings measured externally (portable instruments): <strong>RMS velocity in mm\/s<\/strong>. For large turbo-machinery with journal bearings and installed proximity probes: <strong>peak-to-peak shaft displacement in \u03bcm<\/strong>. If both are available, evaluate both \u2014 they provide complementary information.<\/p>\n\n<p><strong>How do I determine the machine group?<\/strong><\/p>\n<p>Two factors: power rating (above or below 300 kW) and foundation type (rigid or flexible). A 75 kW motor bolted to a concrete pad = Group 2. A 500 kW compressor on a steel platform = Group 3. See the Machine Groups section above.<\/p>\n\n<p><strong>Can a machine in Zone B still have a developing fault?<\/strong><\/p>\n<p>Yes \u2014 this is exactly why Criterion 2 exists. If a machine's baseline was 0.8 mm\/s and it rises to 2.2 mm\/s, it's still in Zone B for Group 2 (below 2.8 mm\/s), but the 2.75\u00d7 increase from baseline indicates a significant developing problem.<\/p>\n\n<p><strong>What vibration level should I target after balancing?<\/strong><\/p>\n<p>After field balancing, aim for <strong>Zone A<\/strong> (below the A\/B boundary for your machine group). For a Group 2 machine, this means below 1.4 mm\/s. The <a href=\"https:\/\/vibromera.eu\/glossary\/balancing\/\">Balancing Guide<\/a> covers the procedure in detail.<\/p>\n\n<p><strong>What frequency range does the broadband RMS velocity cover?<\/strong><\/p>\n<p>Standard range is 10\u20131000 Hz per ISO 20816-1. This captures the most common fault signatures: 1\u00d7 to ~60\u00d7 for a machine running at 1000 RPM (~17 Hz), or 1\u00d7 to ~20\u00d7 for a machine at 3000 RPM (50 Hz). Low-speed machines (<120 RPM) use an extended range of 2\u20131000 Hz.<\/p>\n\n<p><strong>Do I need to buy the ISO 20816-1 document to use the zone values?<\/strong><\/p>\n<p>ISO 20816-1 itself does not contain specific zone values \u2014 it only defines the methodology. The zone boundary numbers are in <strong>ISO 20816-3<\/strong> (for general industrial machines). For the complete official documents with all procedures and annexes, purchase from <a href=\"https:\/\/www.iso.org\/standard\/63180.html\" rel=\"nofollow noopener\" target=\"_blank\">ISO Store<\/a>. The zone values published in this guide are from publicly available references and widely used in industry.<\/p>\n\n<hr style=\"margin:48px 0 24px;border:none;border-top:1px solid var(--border-light);\">\n\n<h3>Related Articles<\/h3>\n<div class=\"related-grid\">\n<a href=\"https:\/\/vibromera.eu\/glossary\/vibration-analysis\/\" class=\"related-card\">\n<div class=\"rc-title\">Vibration Analysis Guide<\/div>\n<div class=\"rc-desc\">FFT spectrum interpretation, bearing frequency calculator, fault diagnosis patterns<\/div>\n<\/a>\n<a href=\"https:\/\/vibromera.eu\/glossary\/balancing\/\" class=\"related-card\">\n<div class=\"rc-title\">Field Dynamic Balancing<\/div>\n<div class=\"rc-desc\">ISO 1940-1 tolerance calculator, two-plane procedure with Balanset-1A<\/div>\n<\/a>\n<a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\" class=\"related-card\">\n<div class=\"rc-title\">Balanset-1A Device<\/div>\n<div class=\"rc-desc\">Two-channel portable vibration analyzer and balancer \u2014 specifications and ordering<\/div>\n<\/a>\n<\/div>\n\n<hr style=\"margin:24px 0;border:none;border-top:1px solid var(--border-light);\">\n<p><a href=\"https:\/\/vibromera.eu\/glossary\/\">\u2190 Back to Glossary Index<\/a><\/p>\n\n<\/article>\n\n<aside class=\"toc-sidebar\">\n<div class=\"toc-box\">\n<h3>On This Page<\/h3>\n<a href=\"#calculators\">Calculators<\/a>\n<a class=\"sub\" href=\"#calculators\">Zone checker<\/a>\n<a class=\"sub\" href=\"#calculators\">Alarm setpoint<\/a>\n<a class=\"sub\" href=\"#calculators\">Unit converter<\/a>\n<a class=\"sub\" href=\"#calculators\">Shaft displacement<\/a>\n<a href=\"#what-is\">What Is ISO 20816-1<\/a>\n<a href=\"#series\">The 20816 Series<\/a>\n<a class=\"sub\" href=\"#series\">All parts table<\/a>\n<a href=\"#measurement\">Measurement Types<\/a>\n<a class=\"sub\" href=\"#measurement\">Casing vibration<\/a>\n<a class=\"sub\" href=\"#measurement\">Shaft vibration<\/a>\n<a class=\"sub\" href=\"#measurement\">Instrumentation<\/a>\n<a href=\"#zones\">Evaluation Zones A\u2013D<\/a>\n<a class=\"sub\" href=\"#zones\">Zone definitions<\/a>\n<a class=\"sub\" href=\"#zones\">Casing boundaries (20816-3)<\/a>\n<a class=\"sub\" href=\"#zones\">Shaft boundaries (20816-2)<\/a>\n<a href=\"#criteria\">Dual Criteria<\/a>\n<a class=\"sub\" href=\"#criteria\">Criterion 1 \u2014 Absolute<\/a>\n<a class=\"sub\" href=\"#criteria\">Criterion 2 \u2014 Change<\/a>\n<a href=\"#groups\">Machine Groups<\/a>\n<a href=\"#alarms\">Alarm & Trip Setpoints<\/a>\n<a href=\"#acceptance\">Acceptance vs Monitoring<\/a>\n<a href=\"#migration\">ISO 10816 Migration<\/a>\n<a href=\"#balanset\">Balanset-1A Application<\/a>\n<a href=\"#faq\">FAQ<\/a>\n<\/div>\n<\/aside>\n\n<\/div>\n<\/div>\n<\/main>\n\n<section class=\"shop-cta\">\n<div class=\"container\">\n<h2>Measure Vibration Per ISO 20816<\/h2>\n<p>The Balanset-1A measures broadband RMS velocity \u2014 the exact parameter specified by ISO 20816 for casing vibration assessment. Two channels, FFT spectrum, and built-in balancing capability.<\/p>\n<a href=\"https:\/\/vibromera.eu\/product\/balanset-1\/\" class=\"cta-btn\">View Balanset-1A Device \u2192<\/a>\n<\/div>\n<\/section>\n\n<footer class=\"page-footer\">\n<div class=\"container\">\n<p>\u00a9 2025 Vibromera. <a href=\"https:\/\/vibromera.eu\/glossary\/\">Glossary Index<\/a> \u00b7 <a href=\"https:\/\/vibromera.eu\/\">vibromera.eu<\/a><\/p>\n<\/div>\n<\/footer>\n\n<script>\n\/* Zone boundaries: [A\/B, B\/C, C\/D] per group *\/\nvar ZB={1:[2.3,4.5,7.1],2:[1.4,2.8,7.1],3:[3.5,7.1,11.2],4:[2.3,4.5,11.2]};\n\n\/* ===== ZONE CHECKER ===== *\/\nfunction calcZone(){\n var g=parseInt(document.getElementById('zc-group').value);\n var v=parseFloat(document.getElementById('zc-vel').value)||0;\n var b=ZB[g];\n var zone,action,cls;\n if(v<=b[0]){zone='Zone A';action='Excellent \u2014 newly commissioned condition';cls='zone-a';}\n else if(v<=b[1]){zone='Zone B';action='Acceptable for unrestricted long-term operation';cls='zone-b';}\n else if(v<=b[2]){zone='Zone C';action='Unsatisfactory \u2014 plan corrective action';cls='zone-c';}\n else{zone='Zone D';action='SEVERE \u2014 take immediate action \/ shutdown';cls='zone-d';}\n document.getElementById('zc-zone').textContent=zone+' ('+v+' mm\/s)';\n document.getElementById('zc-action').textContent=action;\n document.getElementById('zc-ab').textContent=b[0];\n document.getElementById('zc-bc').textContent=b[1];\n document.getElementById('zc-cd').textContent=b[2];\n var margin=b[1]-v;\n document.getElementById('zc-margin').textContent=margin>0?margin.toFixed(1):'EXCEEDED';\n var sev=document.getElementById('zc-severity');\n sev.className='severity-result '+cls;\n sev.textContent=zone+' \u2014 Group '+g+': '+action;\n document.getElementById('zc-results').classList.add('active');\n}\n\n\/* ===== ALARM SETPOINT ===== *\/\nfunction calcAlarm(){\n var base=parseFloat(document.getElementById('al-base').value)||0;\n var mult=parseFloat(document.getElementById('al-mult').value)||2.5;\n var g=parseInt(document.getElementById('al-group').value);\n var b=ZB[g];\n var relAlert=base*mult;\n var absAlert=b[1];\n var trip=b[2];\n var effective=Math.min(relAlert,absAlert);\n document.getElementById('al-rel-alert').textContent=relAlert.toFixed(1);\n document.getElementById('al-abs-alert').textContent=absAlert.toFixed(1);\n document.getElementById('al-alert').textContent=effective.toFixed(1);\n document.getElementById('al-trip').textContent=trip.toFixed(1);\n document.getElementById('al-results').classList.add('active');\n}\n\n\/* ===== UNIT CONVERTER ===== *\/\nfunction calcUnits(){\n var val=parseFloat(document.getElementById('uc-val').value)||0;\n var from=document.getElementById('uc-from').value;\n var freq=parseFloat(document.getElementById('uc-freq').value)||1;\n var omega=2*Math.PI*freq;\n \/* Convert everything to mm\/s RMS first *\/\n var velRMS;\n switch(from){\n case 'vel': velRMS=val; break;\n case 'disp': velRMS=(val\/1000)*omega\/Math.sqrt(2)*1000*Math.PI; \/* \u03bcm pk-pk to mm\/s RMS *\/ velRMS=val*omega\/(2*Math.sqrt(2)*1000); break;\n case 'acc': velRMS=val*1000\/omega; break;\n case 'g': velRMS=val*9810\/omega; break;\n case 'ips': velRMS=val*25.4\/Math.sqrt(2); break;\n case 'mil': var um=val*25.4; velRMS=um*omega\/(2*Math.sqrt(2)*1000); break;\n }\n \/* From mm\/s RMS to all others *\/\n var dispPP=velRMS*2*Math.sqrt(2)*1000\/omega; \/* \u03bcm pk-pk *\/\n var accRMS=velRMS*omega\/1000; \/* m\/s\u00b2 *\/\n var gRMS=accRMS\/9.81;\n var ipsPk=velRMS*Math.sqrt(2)\/25.4;\n var milPP=dispPP\/25.4;\n document.getElementById('uc-vel').textContent=velRMS.toFixed(3);\n document.getElementById('uc-disp').textContent=dispPP.toFixed(1);\n document.getElementById('uc-acc').textContent=accRMS.toFixed(3);\n document.getElementById('uc-g').textContent=gRMS.toFixed(4);\n document.getElementById('uc-ips').textContent=ipsPk.toFixed(4);\n document.getElementById('uc-mil').textContent=milPP.toFixed(2);\n document.getElementById('uc-results').classList.add('active');\n}\n\n\/* ===== SHAFT DISPLACEMENT ZONE CHECKER ===== *\/\nfunction calcShaft(){\n var type=document.getElementById('sd-type').value;\n var rpm=parseFloat(document.getElementById('sd-rpm').value)||1;\n var disp=parseFloat(document.getElementById('sd-disp').value)||0;\n \/* k factors [A\/B, B\/C, C\/D] *\/\n var k;\n switch(type){\n case 'turbo': k=[50,80,100]; break;\n case 'hydro': k=[60,100,125]; break;\n case 'pump-gen': k=[55,90,110]; break;\n }\n var factor=Math.sqrt(9000\/rpm);\n var ab=k[0]*factor, bc=k[1]*factor, cd=k[2]*factor;\n var zone,action,cls;\n if(disp<=ab){zone='Zone A';action='Excellent shaft condition';cls='zone-a';}\n else if(disp<=bc){zone='Zone B';action='Acceptable for long-term operation';cls='zone-b';}\n else if(disp<=cd){zone='Zone C';action='Unsatisfactory \u2014 investigate and plan action';cls='zone-c';}\n else{zone='Zone D';action='SEVERE \u2014 risk of rub\/damage, consider shutdown';cls='zone-d';}\n document.getElementById('sd-zone').textContent=zone+' ('+disp+' \u03bcm)';\n document.getElementById('sd-action').textContent=action;\n document.getElementById('sd-ab').textContent=Math.round(ab);\n document.getElementById('sd-bc').textContent=Math.round(bc);\n document.getElementById('sd-cd').textContent=Math.round(cd);\n var sev=document.getElementById('sd-severity');\n sev.className='severity-result '+cls;\n sev.textContent=zone+' \u2014 '+action;\n document.getElementById('sd-results').classList.add('active');\n}\n\ndocument.addEventListener('DOMContentLoaded',function(){calcZone();calcAlarm();calcUnits();calcShaft();});\n<\/script>\n<\/body>\n<\/html><\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>An overview of ISO 20816-1, the current standard for the measurement and evaluation of machine vibration, covering both non-rotating parts and rotating shafts.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[109,112],"tags":[],"class_list":["post-12","glossary","type-glossary","status-publish","hentry","category-glossary","category-iso-standards"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/glossary\/12","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/types\/glossary"}],"version-history":[{"count":7,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/glossary\/12\/revisions"}],"predecessor-version":[{"id":101736,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/glossary\/12\/revisions\/101736"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/media?parent=12"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/categories?post=12"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/tags?post=12"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}