{"id":100287,"date":"2026-02-15T20:31:56","date_gmt":"2026-02-15T20:31:56","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100287"},"modified":"2026-04-05T15:33:43","modified_gmt":"2026-04-05T15:33:43","slug":"vibration-iso20816-3-industrial","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/nb\/calculators\/vibration-iso20816-3-industrial\/","title":{"rendered":"ISO 20816-3 Vibrasjonsgrenser: Maskiner 15 kW\u201350 MW | Vibromera"},"content":{"rendered":"\r\n<script type=\"application\/ld+json\">\r\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Vibration Limits Calculator \u2014 ISO 20816-3 Industrial Machines\",\"alternateName\":[\"ISO 20816-3 Calculator\",\"Industrial Machine Vibration Limits\",\"Motor Vibration Evaluation\"],\"description\":\"Free online vibration zone evaluation calculator per ISO 20816-3 for industrial machines 15 kW to 50 MW.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/vibration-iso20816-3-industrial\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any (Web Browser)\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2025-01-01\",\"dateModified\":\"2025-02-14\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true,\"featureList\":[\"ISO 20816-3 zone evaluation\",\"Machine groups 1\u20134\",\"Rigid and flexible support\",\"Color-coded zone display\",\"Visual zone bar\"],\"keywords\":\"vibration limits, ISO 20816-3, industrial machines, motor, pump, compressor\"}\r\n<\/script>\r\n\r\n<script type=\"application\/ld+json\">\r\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\r\n{\"@type\":\"Question\",\"name\":\"What machines does ISO 20816-3 cover?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ISO 20816-3 covers industrial machines with power ratings from 15 kW to 50 MW, including electric motors, generators, pumps, compressors, fans, and blowers. It replaces the former ISO 10816-3 standard.\"}},\r\n{\"@type\":\"Question\",\"name\":\"How do I determine the machine group?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Group 1: Large machines >300 kW on rigid foundations. Group 2: Medium machines 15\u2013300 kW on rigid foundations. Group 3: Pumps (multistage, vertical, submersible). Group 4: Large machines >300 kW on flexible (soft) foundations. The foundation type is as important as the power rating.\"}},\r\n{\"@type\":\"Question\",\"name\":\"What is the difference between rigid and flexible support?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Rigid support means the machine foundation natural frequency is well above the operating speed (typically concrete block or heavy steel baseplate). Flexible support means the foundation natural frequency is below or near the operating speed (such as steel frame structures, offshore platforms, or elevated floors). Flexible supports generally result in higher vibration levels, so the zone limits are more relaxed.\"}},\r\n{\"@type\":\"Question\",\"name\":\"What velocity measurement is used?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Vibration velocity in mm\/s RMS (root mean square), measured on the bearing housing in the frequency range 10\u20131000 Hz. Broadband RMS velocity is the standard parameter for evaluating industrial machine condition per ISO 20816-3.\"}},\r\n{\"@type\":\"Question\",\"name\":\"How does ISO 20816-3 differ from ISO 10816-3?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ISO 20816-3 replaces ISO 10816-3 with essentially the same zone boundaries and machine group definitions. The main changes are editorial updates, alignment with the ISO 20816 series structure, and additional guidance on evaluation methodology. 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border-radius:var(--vc-radius); text-decoration:none; transition:all 0.15s; }\r\n.vc-related-link:hover { border-color:var(--vc-accent); color:var(--vc-accent); background:var(--vc-accent-light); }\r\n\r\n.vc-promo { margin-top:24px; padding:20px; background:linear-gradient(135deg, var(--vc-accent-light), var(--vc-surface)); border:1px solid var(--vc-border); border-radius:var(--vc-radius-lg); display:flex; align-items:center; gap:16px; }\r\n.vc-promo-text { flex:1; font-size:14px; color:var(--vc-ink-secondary); }\r\n.vc-promo-text strong { color:var(--vc-ink); }\r\n.vc-promo-link { padding:8px 20px; font-size:13px; font-weight:700; color:#fff; background:var(--vc-accent); border-radius:var(--vc-radius); text-decoration:none; white-space:nowrap; transition:background 0.15s; }\r\n.vc-promo-link:hover { background:var(--vc-accent-hover); }\r\n\r\n.vc-footer { text-align:center; padding:32px 16px; font-size:13px; color:var(--vc-ink-muted); }\r\n.vc-footer a { color:var(--vc-accent); text-decoration:none; }\r\n.vc-footer a:hover { text-decoration:underline; }\r\n.vc-footer-links { margin-top:8px; font-size:12px; }\r\n.vc-footer-links a { margin:0 8px; }\r\n\r\n@media print {\r\n    .vc-section-body { max-height:none!important; }\r\n    .vc-faq-a { max-height:none!important; }\r\n    .vc-results { max-height:none!important; padding:24px!important; }\r\n    .vc-copy-btn, .vc-section-chevron, .vc-faq-chevron, .vc-presets, .vc-promo { display:none!important; }\r\n}\r\n<\/style>\r\n\r\n<div class=\"vc-calculator\" id=\"vc-iso20816-3\">\r\n\r\n<header class=\"vc-header\">\r\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool #021<\/p>\r\n    <h1 class=\"vc-header-title\">Vibration Limits \u2014 Industrial Machines 15 kW\u201350 MW<\/h1>\r\n    <p class=\"vc-header-subtitle\">Evaluate vibration severity for industrial rotating machines per ISO 20816-3. Select machine group, support type, enter measured velocity, and get the zone classification.<\/p>\r\n    <div class=\"vc-badges\">\r\n        <span class=\"vc-badge\">ISO 20816-3<\/span>\r\n        <span class=\"vc-badge\">Zones A\/B\/C\/D<\/span>\r\n        <span class=\"vc-badge\">15 kW \u2013 50 MW<\/span>\r\n    <\/div>\r\n<\/header>\r\n\r\n<div class=\"vc-card\">\r\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\r\n        <div class=\"vc-form-grid\">\r\n            <div class=\"vc-field\">\r\n                <label class=\"vc-label\" for=\"vc-group\">Machine Group<\/label>\r\n                <select class=\"vc-select\" id=\"vc-group\">\r\n                    <option value=\"1\">Group 1 \u2014 Large machines &gt;300 kW, rigid foundation<\/option>\r\n                    <option value=\"2\" selected>Group 2 \u2014 Medium machines 15\u2013300 kW, rigid foundation<\/option>\r\n                    <option value=\"3\">Group 3 \u2014 Pumps (multistage, vertical, etc.)<\/option>\r\n                    <option value=\"4\">Group 4 \u2014 Large machines &gt;300 kW, flexible foundation<\/option>\r\n                <\/select>\r\n            <\/div>\r\n            <div class=\"vc-field\">\r\n                <label class=\"vc-label\" for=\"vc-support\">Support Type<\/label>\r\n                <select class=\"vc-select\" id=\"vc-support\">\r\n                    <option value=\"rigid\" selected>Rigid foundation<\/option>\r\n                    <option value=\"flexible\">Flexible foundation<\/option>\r\n                <\/select>\r\n            <\/div>\r\n            <div class=\"vc-field vc-field-full\">\r\n                <label class=\"vc-label\" for=\"vc-value\">Measured Velocity <span class=\"vc-label-hint\">(mm\/s RMS)<\/span><\/label>\r\n                <input class=\"vc-input\" type=\"number\" id=\"vc-value\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 3.2\" value=\"3.2\">\r\n            <\/div>\r\n        <\/div>\r\n\r\n        <div class=\"vc-presets\">\r\n            <div class=\"vc-presets-label\">Quick presets<\/div>\r\n            <button type=\"button\" class=\"vc-preset-btn\" data-g=\"3\" data-s=\"rigid\" data-v=\"3.2\">Pump 3.2 mm\/s<\/button>\r\n            <button type=\"button\" class=\"vc-preset-btn\" data-g=\"2\" data-s=\"rigid\" data-v=\"2.1\">Motor 75 kW, 2.1 mm\/s<\/button>\r\n            <button type=\"button\" class=\"vc-preset-btn\" data-g=\"1\" data-s=\"rigid\" data-v=\"5.5\">Compressor 500 kW, 5.5 mm\/s<\/button>\r\n        <\/div>\r\n    <\/form>\r\n\r\n    <div class=\"vc-results\" id=\"vc-results\">\r\n        <div class=\"vc-results-head\">\r\n            <h2 class=\"vc-results-title\">Results<\/h2>\r\n            <button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\">\r\n                <svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg>\r\n                Copy\r\n            <\/button>\r\n        <\/div>\r\n\r\n        <div class=\"vc-zone-bar\" id=\"vc-zone-bar\">\r\n            <div class=\"vc-zone-bar-seg zb-a\" id=\"zb-a\">A<\/div>\r\n            <div class=\"vc-zone-bar-seg zb-b\" id=\"zb-b\">B<\/div>\r\n            <div class=\"vc-zone-bar-seg zb-c\" id=\"zb-c\">C<\/div>\r\n            <div class=\"vc-zone-bar-seg zb-d\" id=\"zb-d\">D<\/div>\r\n        <\/div>\r\n        <div class=\"vc-zone-bar-labels\" id=\"vc-zone-labels\">\r\n            <span id=\"zl-a\"><\/span><span id=\"zl-b\"><\/span><span id=\"zl-c\"><\/span><span id=\"zl-d\"><\/span>\r\n        <\/div>\r\n\r\n        <div class=\"vc-result-grid\">\r\n            <div class=\"vc-rcard vc-rcard-primary\" id=\"vc-r-zone-card\">\r\n                <div class=\"vc-rcard-label\">Vibration Zone<\/div>\r\n                <div class=\"vc-rcard-value\" id=\"vc-r-zone\">\u2014<\/div>\r\n                <div class=\"vc-rcard-desc\" id=\"vc-r-zone-desc\"><\/div>\r\n            <\/div>\r\n            <div class=\"vc-rcard\">\r\n                <div class=\"vc-rcard-label\">Measured Velocity<\/div>\r\n                <div class=\"vc-rcard-value\" id=\"vc-r-measured\">\u2014<\/div>\r\n            <\/div>\r\n            <div class=\"vc-rcard\">\r\n                <div class=\"vc-rcard-label\">Recommendation<\/div>\r\n                <div class=\"vc-rcard-value\" id=\"vc-r-action\" style=\"font-size:16px;\">\u2014<\/div>\r\n            <\/div>\r\n        <\/div>\r\n\r\n        <table class=\"vc-zone-table\" id=\"vc-boundary-table\">\r\n            <thead><tr><th>Zone<\/th><th>Boundary (mm\/s RMS)<\/th><th>Description<\/th><\/tr><\/thead>\r\n            <tbody id=\"vc-boundary-body\"><\/tbody>\r\n        <\/table>\r\n    <\/div>\r\n<\/div>\r\n\r\n<!-- Theory -->\r\n<div class=\"vc-section vc-open\" id=\"vc-sec-theory\">\r\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\">\r\n        <span class=\"vc-section-toggle-text\">\r\n            <span class=\"vc-section-icon\">\ud83d\udcd8<\/span>\r\n            <span class=\"vc-section-title\">Theory &amp; Formulas<\/span>\r\n        <\/span>\r\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\r\n    <\/button>\r\n    <div class=\"vc-section-body\">\r\n        <div class=\"vc-section-inner vc-theory\">\r\n            <h3>ISO 20816-3 Scope<\/h3>\r\n            <p>ISO 20816-3 provides vibration evaluation criteria for industrial machines with power ratings from 15 kW to 50 MW, operating at speeds between 120 and 15,000 RPM. This is the most widely used standard for evaluating industrial rotating equipment including:<\/p>\r\n            <ul>\r\n                <li>Electric motors and generators<\/li>\r\n                <li>Centrifugal and axial pumps<\/li>\r\n                <li>Compressors (centrifugal, axial, screw)<\/li>\r\n                <li>Fans and blowers<\/li>\r\n                <li>Gearboxes (input\/output shafts)<\/li>\r\n            <\/ul>\r\n\r\n            <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\r\n\r\n            <h3>Zone Boundaries by Machine Group<\/h3>\r\n            <p>Zone boundaries depend on the machine group, which combines power rating and foundation type:<\/p>\r\n            <table class=\"vc-table\">\r\n                <thead><tr><th>Zone Boundary<\/th><th>Group 1<br><small>Large rigid<\/small><\/th><th>Group 2<br><small>Medium rigid<\/small><\/th><th>Group 3<br><small>Pumps<\/small><\/th><th>Group 4<br><small>Large flexible<\/small><\/th><\/tr><\/thead>\r\n                <tbody>\r\n                    <tr><td>A\/B<\/td><td>2.3 mm\/s<\/td><td>1.4 mm\/s<\/td><td>2.3 mm\/s<\/td><td>3.5 mm\/s<\/td><\/tr>\r\n                    <tr><td>B\/C<\/td><td>4.5 mm\/s<\/td><td>2.8 mm\/s<\/td><td>4.5 mm\/s<\/td><td>7.1 mm\/s<\/td><\/tr>\r\n                    <tr><td>C\/D<\/td><td>7.1 mm\/s<\/td><td>4.5 mm\/s<\/td><td>7.1 mm\/s<\/td><td>11.0 mm\/s<\/td><\/tr>\r\n                <\/tbody>\r\n            <\/table>\r\n\r\n            <h3>Measurement Requirements<\/h3>\r\n            <div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div>\r\n            <p>Vibration velocity is measured in mm\/s RMS on the bearing housing in two radial directions (horizontal and vertical) and optionally in the axial direction. The highest reading governs the zone evaluation.<\/p>\r\n\r\n            <div class=\"vc-example-box\">\r\n                <div class=\"vc-example-title\">Example \u2014 Centrifugal Pump 55 kW<\/div>\r\n                <p><strong>Given:<\/strong> Group 3 (pump), measured velocity = 3.2 mm\/s RMS<\/p>\r\n                <p>Zone boundaries for Group 3: A\/B = 2.3, B\/C = 4.5, C\/D = 7.1 mm\/s<\/p>\r\n                <p>3.2 mm\/s is between 2.3 and 4.5 \u2192 <strong>Zone B \u2014 acceptable for long-term operation<\/strong><\/p>\r\n            <\/div>\r\n\r\n            <div class=\"vc-warning-box\">\r\n                <p style=\"margin:0;font-size:14px;color:var(--vc-ink-secondary);\"><strong>\u26a0\ufe0f Important:<\/strong> Always consider vibration trending in addition to absolute levels. A significant increase (e.g., doubling) from baseline may warrant investigation even if the absolute level is within Zone A or B.<\/p>\r\n            <\/div>\r\n        <\/div>\r\n    <\/div>\r\n<\/div>\r\n\r\n<!-- Related -->\r\n<div class=\"vc-section\" id=\"vc-sec-related\">\r\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\r\n        <span class=\"vc-section-toggle-text\">\r\n            <span class=\"vc-section-icon\">\ud83d\udd17<\/span>\r\n            <span class=\"vc-section-title\">Related Calculators<\/span>\r\n        <\/span>\r\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\r\n    <\/button>\r\n    <div class=\"vc-section-body\">\r\n        <div class=\"vc-section-inner\">\r\n            <div class=\"vc-related\">\r\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-zones-iso20816-1\/\">ISO 20816-1 \u2014 General Guidelines<\/a>\r\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-2-turbines\/\">ISO 20816-2 \u2014 Steam Turbines<\/a>\r\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-4-gas-turbines\/\">ISO 20816-4 \u2014 Gas Turbines<\/a>\r\n                <a class=\"vc-related-link\" href=\"\/calculators\/residual-unbalance-iso1940\/\">Residual Unbalance (ISO 21940)<\/a>\r\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-velocity\/\">Vibration Velocity (ISO 10816)<\/a>\r\n            <\/div>\r\n        <\/div>\r\n    <\/div>\r\n<\/div>\r\n\r\n<!-- FAQ -->\r\n<div class=\"vc-section\" id=\"vc-sec-faq\">\r\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\r\n        <span class=\"vc-section-toggle-text\">\r\n            <span class=\"vc-section-icon\">\u2753<\/span>\r\n            <span class=\"vc-section-title\">Frequently Asked Questions<\/span>\r\n        <\/span>\r\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\r\n    <\/button>\r\n    <div class=\"vc-section-body\">\r\n        <div class=\"vc-section-inner\">\r\n            <div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div>\r\n        <\/div>\r\n    <\/div>\r\n<\/div>\r\n\r\n<div class=\"vc-promo\">\r\n    <div class=\"vc-promo-text\">\r\n        <strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>\r\n        Professional field balancing instruments and vibration analyzers for industrial machines. Evaluate condition per ISO 20816-3 on-site. Used in 50+ countries.\r\n    <\/div>\r\n    <a class=\"vc-promo-link\" href=\"https:\/\/vibromera.eu\/\" target=\"_blank\" rel=\"noopener\">Learn More<\/a>\r\n<\/div>\r\n\r\n<footer class=\"vc-footer\">\r\n    <p>\u00a9 2024\u20132025 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a> \u2014 Engineering Calculators<\/p>\r\n    <p style=\"font-size:12px;margin-top:4px;\">Based on ISO 20816-3. Last updated: February 2025<\/p>\r\n    <div class=\"vc-footer-links\">\r\n        <a href=\"\/calculators\/engineering-calculators\/\">All Calculators<\/a>\r\n        <a href=\"https:\/\/vibromera.eu\/contacts\/\">Contact<\/a>\r\n    <\/div>\r\n<\/footer>\r\n\r\n<\/div>\r\n\r\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/katex@0.16.11\/dist\/katex.min.js\"><\/script>\r\n<script>\r\n(function() {\r\n    'use strict';\r\n\r\n    var SLUG = 'vibration-iso20816-3-industrial';\r\n\r\n    var ZONES = {\r\n        '1': { name: 'Group 1 \u2014 Large rigid (>300 kW)', ab: 2.3, bc: 4.5, cd: 7.1 },\r\n        '2': { name: 'Group 2 \u2014 Medium rigid (15\u2013300 kW)', ab: 1.4, bc: 2.8, cd: 4.5 },\r\n        '3': { name: 'Group 3 \u2014 Pumps', ab: 2.3, bc: 4.5, cd: 7.1 },\r\n        '4': { name: 'Group 4 \u2014 Large flexible (>300 kW)', ab: 3.5, bc: 7.1, cd: 11.0 }\r\n    };\r\n\r\n    var ZONE_DESC = {\r\n        A: 'Newly commissioned machines \u2014 excellent condition',\r\n        B: 'Acceptable for unrestricted long-term operation',\r\n        C: 'Not suitable for long-term operation \u2014 plan remedial action',\r\n        D: 'Dangerous vibration level \u2014 risk of damage, immediate action required'\r\n    };\r\n\r\n    var ZONE_ACTION = {\r\n        A: 'No action required \u2014 machine in excellent condition',\r\n        B: 'Continue normal operation and routine monitoring',\r\n        C: 'Investigate root cause; schedule corrective maintenance; increase monitoring',\r\n        D: 'Immediate shutdown or load reduction \u2014 risk of damage'\r\n    };\r\n\r\n    function $(id) { return document.getElementById(id); }\r\n    function fmt(n, d) { if(isNaN(n)) return '\u2014'; var f=n.toFixed(d===undefined?2:d); return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,''); }\r\n\r\n    function getZone(val, z) {\r\n        if (val <= z.ab) return 'A';\r\n        if (val <= z.bc) return 'B';\r\n        if (val <= z.cd) return 'C';\r\n        return 'D';\r\n    }\r\n\r\n    function calculate() {\r\n        var group = $('vc-group').value;\r\n        var support = $('vc-support').value;\r\n        var val = parseFloat($('vc-value').value);\r\n\r\n        if (isNaN(val) || val < 0) {\r\n            $('vc-results').classList.remove('vc-visible');\r\n            return;\r\n        }\r\n\r\n        var z = ZONES[group];\r\n        var zone = getZone(val, z);\r\n\r\n        ['a','b','c','d'].forEach(function(letter) {\r\n            var seg = $('zb-' + letter);\r\n            seg.className = 'vc-zone-bar-seg zb-' + letter + (letter.toUpperCase() === zone ? ' zb-active' : ' zb-dim');\r\n        });\r\n\r\n        $('zl-a').textContent = '\u2264' + z.ab;\r\n        $('zl-b').textContent = z.ab + '\u2013' + z.bc;\r\n        $('zl-c').textContent = z.bc + '\u2013' + z.cd;\r\n        $('zl-d').textContent = '>' + z.cd;\r\n\r\n        var zoneCard = $('vc-r-zone-card');\r\n        zoneCard.className = 'vc-rcard vc-rcard-primary vc-zone-' + zone.toLowerCase();\r\n        $('vc-r-zone').textContent = 'Zone ' + zone;\r\n        $('vc-r-zone-desc').textContent = ZONE_DESC[zone];\r\n\r\n        $('vc-r-measured').innerHTML = fmt(val, 2) + ' <span class=\"vc-rcard-unit\">mm\/s RMS<\/span>';\r\n        $('vc-r-action').textContent = ZONE_ACTION[zone];\r\n\r\n        var tbody = $('vc-boundary-body');\r\n        tbody.innerHTML =\r\n            '<tr class=\"zt-a\"><td><strong>Zone A<\/strong><\/td><td>\u2264 ' + z.ab + '<\/td><td>' + ZONE_DESC.A + '<\/td><\/tr>' +\r\n            '<tr class=\"zt-b\"><td><strong>Zone B<\/strong><\/td><td>' + z.ab + ' \u2013 ' + z.bc + '<\/td><td>' + ZONE_DESC.B + '<\/td><\/tr>' +\r\n            '<tr class=\"zt-c\"><td><strong>Zone C<\/strong><\/td><td>' + z.bc + ' \u2013 ' + z.cd + '<\/td><td>' + ZONE_DESC.C + '<\/td><\/tr>' +\r\n            '<tr class=\"zt-d\"><td><strong>Zone D<\/strong><\/td><td>&gt; ' + z.cd + '<\/td><td>' + ZONE_DESC.D + '<\/td><\/tr>';\r\n\r\n        $('vc-results').classList.add('vc-visible');\r\n\r\n        var u = new URL(window.location);\r\n        u.searchParams.set('group', group);\r\n        u.searchParams.set('support', support);\r\n        u.searchParams.set('value', val);\r\n        history.replaceState(null, '', u.toString());\r\n\r\n        saveHistory({ group: group, support: support, value: val, zone: zone, _summary: z.name + ', ' + val + ' mm\/s \u2192 Zone ' + zone });\r\n    }\r\n\r\n    \/* Auto-link group & support *\/\r\n    $('vc-group').addEventListener('change', function() {\r\n        var g = this.value;\r\n        if (g === '4') {\r\n            $('vc-support').value = 'flexible';\r\n        } else {\r\n            $('vc-support').value = 'rigid';\r\n        }\r\n        calculate();\r\n    });\r\n\r\n    document.querySelectorAll('.vc-preset-btn').forEach(function(btn) {\r\n        btn.addEventListener('click', function(e) {\r\n            e.preventDefault();\r\n            $('vc-group').value = this.getAttribute('data-g');\r\n            $('vc-support').value = this.getAttribute('data-s');\r\n            $('vc-value').value = this.getAttribute('data-v');\r\n            calculate();\r\n        });\r\n    });\r\n\r\n    $('vc-form').addEventListener('input', calculate);\r\n    $('vc-form').addEventListener('change', calculate);\r\n\r\n    $('vc-copy-btn').addEventListener('click', function() {\r\n        var z = ZONES[$('vc-group').value];\r\n        var text = 'Vibration Zone Evaluation \u2014 ISO 20816-3\\n' +\r\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\r\n            'Machine Group: ' + z.name + '\\n' +\r\n            'Support: ' + $('vc-support').options[$('vc-support').selectedIndex].text + '\\n' +\r\n            'Measured: ' + $('vc-r-measured').textContent + '\\n' +\r\n            'Zone: ' + $('vc-r-zone').textContent + '\\n' +\r\n            'Assessment: ' + $('vc-r-zone-desc').textContent + '\\n' +\r\n            'Action: ' + $('vc-r-action').textContent + '\\n' +\r\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\r\n            'vibromera.eu\/calculators\/vibration-iso20816-3-industrial\/';\r\n\r\n        if (navigator.clipboard) {\r\n            navigator.clipboard.writeText(text).then(function() {\r\n                var btn = $('vc-copy-btn');\r\n                btn.classList.add('vc-copied');\r\n                btn.innerHTML = '<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><polyline points=\"20 6 9 17 4 12\"\/><\/svg> Copied!';\r\n                setTimeout(function() {\r\n                    btn.classList.remove('vc-copied');\r\n                    btn.innerHTML = '<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy';\r\n                }, 2000);\r\n            });\r\n        }\r\n    });\r\n\r\n    document.querySelectorAll('.vc-section-toggle').forEach(function(btn) {\r\n        btn.addEventListener('click', function() {\r\n            var section = this.closest('.vc-section');\r\n            var isOpen = section.classList.contains('vc-open');\r\n            section.classList.toggle('vc-open');\r\n            this.setAttribute('aria-expanded', !isOpen);\r\n        });\r\n    });\r\n\r\n    var faqData = [\r\n        { q: 'What machines does ISO 20816-3 cover?', a: '<p>ISO 20816-3 covers <strong>industrial rotating machines with power ratings from 15 kW to 50 MW<\/strong>, including:<\/p><ul><li>Electric motors and generators (induction, synchronous)<\/li><li>Centrifugal and axial pumps<\/li><li>Compressors (centrifugal, axial, screw, reciprocating)<\/li><li>Fans and blowers<\/li><li>Gearboxes (evaluated at input\/output bearing locations)<\/li><\/ul><p>It replaces the former ISO 10816-3 standard.<\/p>' },\r\n        { q: 'How do I determine the correct machine group?', a: '<p>The machine group depends on <strong>power rating<\/strong> and <strong>foundation type<\/strong>:<\/p><ul><li><strong>Group 1<\/strong> \u2014 Large machines over 300 kW on rigid foundations (concrete block, heavy steel baseplate)<\/li><li><strong>Group 2<\/strong> \u2014 Medium machines 15\u2013300 kW on rigid foundations \u2014 the most common group for standard industrial equipment<\/li><li><strong>Group 3<\/strong> \u2014 Pumps including multistage, vertical, and special-purpose pumps (regardless of power rating)<\/li><li><strong>Group 4<\/strong> \u2014 Large machines over 300 kW on flexible (soft) foundations (steel frames, elevated platforms)<\/li><\/ul>' },\r\n        { q: 'What is the difference between rigid and flexible support?', a: '<p><strong>Rigid support:<\/strong> The foundation natural frequency is well above the machine operating speed. Examples: concrete block foundations, heavy steel baseplates bolted to concrete. The support adds minimal amplification to machine vibration.<\/p><p><strong>Flexible support:<\/strong> The foundation natural frequency is below or near the operating speed. Examples: steel frame structures, mezzanine floors, offshore platforms, skid-mounted units. Vibration levels are typically higher due to dynamic amplification.<\/p>' },\r\n        { q: 'What velocity measurement is used for ISO 20816-3?', a: '<p>Vibration velocity in <strong>mm\/s RMS<\/strong> (root mean square), measured on the bearing housing in the frequency range <strong>10\u20131000 Hz<\/strong>. Measurements should be taken in at least two radial directions (horizontal and vertical) at each bearing location. The highest reading at each bearing governs the zone evaluation.<\/p>' },\r\n        { q: 'How does ISO 20816-3 differ from ISO 10816-3?', a: '<p>ISO 20816-3 replaces ISO 10816-3. The key differences are:<\/p><ul><li>Zone boundaries remain the same \u2014 the limits are identical<\/li><li>The numbering changed to align with the ISO 20816 series<\/li><li>Updated guidance on measurement methodology<\/li><li>Better alignment with companion standards (ISO 20816-1, -2, -4)<\/li><\/ul><p>For practical vibration evaluation, both standards give the same results.<\/p>' }\r\n    ];\r\n\r\n    var faqList = $('vc-faq-list');\r\n    faqData.forEach(function(faq) {\r\n        faqList.innerHTML += '<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>' + faq.q + '<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">' + faq.a + '<\/div><\/div><\/div>';\r\n    });\r\n    faqList.addEventListener('click', function(e) {\r\n        var btn = e.target.closest('.vc-faq-q');\r\n        if (!btn) return;\r\n        btn.closest('.vc-faq-item').classList.toggle('vc-open');\r\n    });\r\n\r\n    function saveHistory(entry) {\r\n        var key = 'vc_history_' + SLUG;\r\n        var arr = [];\r\n        try { arr = JSON.parse(localStorage.getItem(key)) || []; } catch(e) {}\r\n        entry._ts = new Date().toISOString();\r\n        arr.unshift(entry);\r\n        if (arr.length > 10) arr = arr.slice(0, 10);\r\n        try { localStorage.setItem(key, JSON.stringify(arr)); } catch(e) {}\r\n    }\r\n\r\n    function loadParams() {\r\n        var p = new URLSearchParams(window.location.search);\r\n        if (p.has('group')) $('vc-group').value = p.get('group');\r\n        if (p.has('support')) $('vc-support').value = p.get('support');\r\n        if (p.has('value')) $('vc-value').value = p.get('value');\r\n    }\r\n\r\n    function renderFormulas() {\r\n        try {\r\n            katex.render('\\\\text{Zone} = \\\\begin{cases} A & v_{\\\\text{RMS}} \\\\leq v_{A\/B} \\\\\\\\ B & v_{A\/B} < v_{\\\\text{RMS}} \\\\leq v_{B\/C} \\\\\\\\ C & v_{B\/C} < v_{\\\\text{RMS}} \\\\leq v_{C\/D} \\\\\\\\ D & v_{\\\\text{RMS}} > v_{C\/D} \\\\end{cases}', $('vc-katex-1'), { displayMode: true, throwOnError: false });\r\n            katex.render('v_{\\\\text{RMS}} = \\\\sqrt{\\\\frac{1}{T}\\\\int_0^T v(t)^2 \\\\, dt} \\\\quad [\\\\text{mm\/s}]', $('vc-katex-2'), { displayMode: true, throwOnError: false });\r\n        } catch(e) {}\r\n    }\r\n\r\n    function init() {\r\n        loadParams();\r\n        renderFormulas();\r\n        calculate();\r\n    }\r\n\r\n    if (document.readyState === 'loading') {\r\n        document.addEventListener('DOMContentLoaded', init);\r\n    } else {\r\n        init();\r\n    }\r\n})();\r\n<\/script>\r\n","protected":false},"excerpt":{"rendered":"<p>Gratis online kalkulator for evaluering av vibrasjonssoner i henhold til ISO 20816-3 for industrimaskiner 15 kW til 50 MW. Evaluer vibrasjonshastighet mot grenseverdiene for sone A\/B\/C\/D etter maskingruppe og st\u00f8ttetype.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100287","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100287","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":5,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100287\/revisions"}],"predecessor-version":[{"id":100907,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100287\/revisions\/100907"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/media?parent=100287"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/categories?post=100287"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/tags?post=100287"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}