{"id":100289,"date":"2026-02-15T20:32:02","date_gmt":"2026-02-15T20:32:02","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100289"},"modified":"2026-04-05T15:33:29","modified_gmt":"2026-04-05T15:33:29","slug":"vibration-iso20816-5-hydro","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/bn\/calculators\/vibration-iso20816-5-hydro\/","title":{"rendered":"ISO 20816-5 \u09b9\u09be\u0987\u09a1\u09cd\u09b0\u09cb \u099f\u09be\u09b0\u09cd\u09ac\u09be\u0987\u09a8\u09c7\u09b0 \u0995\u09ae\u09cd\u09aa\u09a8 \u09b8\u09c0\u09ae\u09be | Vibromera"},"content":{"rendered":"\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Vibration Limits Calculator \u2014 ISO 20816-5 Hydro Turbines\",\"alternateName\":[\"ISO 20816-5 Calculator\",\"Hydro Turbine Vibration Limits\",\"Pump-Turbine Vibration Evaluation\"],\"description\":\"Free online vibration zone evaluation calculator per ISO 20816-5 for hydraulic turbines, pump-turbines, and pumps.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/vibration-iso20816-5-hydro\/\",\"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 20816-5 zone evaluation\",\"Bearing housing velocity\",\"Shaft relative displacement\",\"Vertical and horizontal machines\",\"Color-coded zone display\"],\"keywords\":\"vibration limits, ISO 20816-5, hydro turbine, Francis, Kaplan, Pelton, pump-turbine, zone A B C D\"}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"What machines does ISO 20816-5 cover?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ISO 20816-5 applies to hydraulic machines including vertical Kaplan turbines, vertical Francis turbines, vertical pump-turbines, horizontal Pelton turbines, and vertical pumps operating in hydroelectric power plants. It covers machines with rated speeds typically from 60 to 1000 RPM.\"}},\n{\"@type\":\"Question\",\"name\":\"Why are hydro turbine vibration limits different from steam turbines?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Hydraulic machines operate at much lower speeds than steam turbines (often 60\u2013500 RPM vs 1500\u20133600 RPM). They also experience hydraulic excitation forces from water flow, draft tube surges, and cavitation, which generate different vibration patterns. Vertical machines have additional considerations for thrust bearing vibration.\"}},\n{\"@type\":\"Question\",\"name\":\"What is shaft displacement measurement in hydro turbines?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Shaft displacement in hydro turbines is measured using proximity probes mounted near the guide bearings, typically measuring peak-to-peak displacement in micrometers (\u03bcm p-p). This is critical for vertical machines where shaft orbit monitoring reveals unbalance, misalignment, and hydraulic instabilities.\"}},\n{\"@type\":\"Question\",\"name\":\"Why do horizontal Pelton turbines have different limits?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Horizontal Pelton turbines have lower vibration limits than vertical machines because horizontal bearing arrangements are more sensitive to dynamic forces. The impulse nature of Pelton wheel jet impact also produces different vibration characteristics compared to reaction turbines like Francis and Kaplan.\"}},\n{\"@type\":\"Question\",\"name\":\"What should I do if vibration reaches Zone C on a hydro turbine?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Zone C indicates the machine is not suitable for continuous long-term operation. Investigate root causes including runner cavitation, draft tube surge, guide bearing wear, shaft misalignment, or hydraulic resonance. 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Pump Units<\/h1>\n    <p class=\"vc-header-subtitle\">Evaluate vibration severity for hydraulic turbines, pump-turbines, and pumps per ISO 20816-5. Supports bearing housing velocity and shaft displacement measurements.<\/p>\n    <div class=\"vc-badges\">\n        <span class=\"vc-badge\">ISO 20816-5<\/span>\n        <span class=\"vc-badge\">Zones A\/B\/C\/D<\/span>\n        <span class=\"vc-badge\">Hydro Machines<\/span>\n    <\/div>\n<\/header>\n\n<div class=\"vc-card\">\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\n        <div class=\"vc-form-grid\">\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-machine\">Machine Type<\/label>\n                <select class=\"vc-select\" id=\"vc-machine\">\n                    <option value=\"vertical-kaplan\" selected>Vertical Kaplan Turbine<\/option>\n                    <option value=\"vertical-francis\">Vertical Francis Turbine<\/option>\n                    <option value=\"vertical-pump-turbine\">Vertical Pump-Turbine<\/option>\n                    <option value=\"horizontal-pelton\">Horizontal Pelton Turbine<\/option>\n                    <option value=\"vertical-pump\">Vertical Pump<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-measurement\">Measurement<\/label>\n                <select class=\"vc-select\" id=\"vc-measurement\">\n                    <option value=\"bearing\" selected>Bearing Housing Velocity (mm\/s RMS)<\/option>\n                    <option value=\"shaft\">Shaft Displacement (\u03bcm p-p)<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field vc-field-full\">\n                <label class=\"vc-label\" for=\"vc-value\">Measured Value <span class=\"vc-label-hint\" id=\"vc-value-hint\">(mm\/s RMS)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-value\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 4.0\" value=\"4.0\">\n            <\/div>\n        <\/div>\n\n        <div class=\"vc-presets\">\n            <div class=\"vc-presets-label\">Quick presets<\/div>\n            <button type=\"button\" class=\"vc-preset-btn\" data-m=\"vertical-francis\" data-l=\"bearing\" data-v=\"4.0\">Francis turbine bearing 4.0 mm\/s<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-m=\"vertical-kaplan\" data-l=\"shaft\" data-v=\"110\">Kaplan shaft 110 \u03bcm<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-m=\"vertical-pump-turbine\" data-l=\"bearing\" data-v=\"6.0\">Pump-turbine 6.0 mm\/s<\/button>\n        <\/div>\n    <\/form>\n\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\">\n            <h2 class=\"vc-results-title\">Results<\/h2>\n            <button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\">\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>\n                Copy\n            <\/button>\n        <\/div>\n\n        <div class=\"vc-zone-bar\" id=\"vc-zone-bar\">\n            <div class=\"vc-zone-bar-seg zb-a\" id=\"zb-a\">A<\/div>\n            <div class=\"vc-zone-bar-seg zb-b\" id=\"zb-b\">B<\/div>\n            <div class=\"vc-zone-bar-seg zb-c\" id=\"zb-c\">C<\/div>\n            <div class=\"vc-zone-bar-seg zb-d\" id=\"zb-d\">D<\/div>\n        <\/div>\n        <div class=\"vc-zone-bar-labels\" id=\"vc-zone-labels\">\n            <span id=\"zl-a\"><\/span><span id=\"zl-b\"><\/span><span id=\"zl-c\"><\/span><span id=\"zl-d\"><\/span>\n        <\/div>\n\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\" id=\"vc-r-zone-card\">\n                <div class=\"vc-rcard-label\">Vibration Zone<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-zone\">\u2014<\/div>\n                <div class=\"vc-rcard-desc\" id=\"vc-r-zone-desc\"><\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Measured Value<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-measured\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Recommendation<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-action\" style=\"font-size:16px;\">\u2014<\/div>\n            <\/div>\n        <\/div>\n\n        <table class=\"vc-zone-table\" id=\"vc-boundary-table\">\n            <thead><tr><th>Zone<\/th><th>Boundary<\/th><th>Description<\/th><\/tr><\/thead>\n            <tbody id=\"vc-boundary-body\"><\/tbody>\n        <\/table>\n    <\/div>\n<\/div>\n\n<!-- Theory -->\n<div class=\"vc-section vc-open\" id=\"vc-sec-theory\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\ud83d\udcd8<\/span>\n            <span class=\"vc-section-title\">Theory &amp; Formulas<\/span>\n        <\/span>\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>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner vc-theory\">\n            <h3>ISO 20816-5 Scope<\/h3>\n            <p>ISO 20816-5 specifies vibration evaluation criteria for hydraulic machines including Kaplan, Francis, and Pelton turbines, pump-turbines, and pumps used in hydroelectric power plants. It covers both vertical and horizontal machine configurations.<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n\n            <h3>Bearing Housing Vibration \u2014 Vertical Machines<\/h3>\n            <p>Broadband vibration velocity measured on the bearing housing in mm\/s RMS, typically 10\u20131000 Hz range. Applies to vertical Kaplan, Francis, pump-turbine, and pump units.<\/p>\n            <table class=\"vc-table\">\n                <thead><tr><th>Zone Boundary<\/th><th>Velocity (mm\/s RMS)<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td>A\/B<\/td><td>2.8<\/td><\/tr>\n                    <tr><td>B\/C<\/td><td>5.3<\/td><\/tr>\n                    <tr><td>C\/D<\/td><td>8.5<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n\n            <h3>Bearing Housing Vibration \u2014 Horizontal Pelton<\/h3>\n            <p>Horizontal Pelton turbines have lower allowable limits due to the bearing arrangement and impulse loading characteristics.<\/p>\n            <table class=\"vc-table\">\n                <thead><tr><th>Zone Boundary<\/th><th>Velocity (mm\/s RMS)<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td>A\/B<\/td><td>2.3<\/td><\/tr>\n                    <tr><td>B\/C<\/td><td>4.5<\/td><\/tr>\n                    <tr><td>C\/D<\/td><td>7.1<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n\n            <h3>Shaft Displacement \u2014 Vertical Machines<\/h3>\n            <p>Shaft relative displacement is measured with proximity probes, expressed as peak-to-peak displacement in \u03bcm.<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div>\n            <table class=\"vc-table\">\n                <thead><tr><th>Zone Boundary<\/th><th>Displacement (\u03bcm p-p)<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td>A\/B<\/td><td>80<\/td><\/tr>\n                    <tr><td>B\/C<\/td><td>160<\/td><\/tr>\n                    <tr><td>C\/D<\/td><td>260<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n\n            <div class=\"vc-info-box\">\n                <p><strong>\u2139\ufe0f Note:<\/strong> Vertical hydro machines have unique vibration characteristics due to gravity acting along the shaft axis. Thrust bearing condition and hydraulic forces (draft tube surge, cavitation) significantly affect vibration behavior.<\/p>\n            <\/div>\n\n            <div class=\"vc-warning-box\">\n                <p style=\"margin:0;font-size:14px;color:var(--vc-ink-secondary);\"><strong>\u26a0\ufe0f Important:<\/strong> Both bearing housing and shaft vibration should be monitored. The worse of the two assessments governs the overall evaluation. Operating conditions (load, head, tailwater level) strongly influence vibration levels in hydro machines.<\/p>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<!-- Related -->\n<div class=\"vc-section\" id=\"vc-sec-related\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\ud83d\udd17<\/span>\n            <span class=\"vc-section-title\">Related Calculators<\/span>\n        <\/span>\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>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner\">\n            <div class=\"vc-related\">\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-zones-iso20816-1\/\">ISO 20816-1 \u2014 General Guidelines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-2-turbines\/\">ISO 20816-2 \u2014 Steam Turbines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-3-industrial\/\">ISO 20816-3 \u2014 Industrial Machines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-4-gas-turbines\/\">ISO 20816-4 \u2014 Gas Turbines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-8-compressors\/\">ISO 20816-8 \u2014 Reciprocating Compressors<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-9-gears\/\">ISO 20816-9 \u2014 Gear Drives<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-21-wind\/\">ISO 20816-21 \u2014 Wind Turbines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/residual-unbalance-iso1940\/\">Residual Unbalance (ISO 21940)<\/a>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<!-- FAQ -->\n<div class=\"vc-section\" id=\"vc-sec-faq\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\u2753<\/span>\n            <span class=\"vc-section-title\">Frequently Asked Questions<\/span>\n        <\/span>\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>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner\">\n            <div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-promo\">\n    <div class=\"vc-promo-text\">\n        <strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>\n        Professional vibration analyzers and field balancing systems for hydroelectric machinery. ISO 20816 compliant evaluation on-site. Used in 50+ countries.\n    <\/div>\n    <a class=\"vc-promo-link\" href=\"https:\/\/vibromera.eu\/\" target=\"_blank\" rel=\"noopener\">Learn More<\/a>\n<\/div>\n\n<footer class=\"vc-footer\">\n    <p>\u00a9 2024\u20132025 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a> \u2014 Engineering Calculators<\/p>\n    <p style=\"font-size:12px;margin-top:4px;\">Based on ISO 20816-5. Last updated: February 2025<\/p>\n    <div class=\"vc-footer-links\">\n        <a href=\"\/calculators\/engineering-calculators\/\">All Calculators<\/a>\n        <a href=\"https:\/\/vibromera.eu\/contacts\/\">Contact<\/a>\n    <\/div>\n<\/footer>\n\n<\/div>\n\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/katex@0.16.11\/dist\/katex.min.js\"><\/script>\n<script>\n(function() {\n    'use strict';\n\n    var SLUG = 'vibration-iso20816-5-hydro';\n\n    var LIMITS = {\n        'vertical-kaplan':        { bearing: { ab:2.8, bc:5.3, cd:8.5, unit:'mm\/s RMS' }, shaft: { ab:80, bc:160, cd:260, unit:'\u03bcm p-p' } },\n        'vertical-francis':       { bearing: { ab:2.8, bc:5.3, cd:8.5, unit:'mm\/s RMS' }, shaft: { ab:80, bc:160, cd:260, unit:'\u03bcm p-p' } },\n        'vertical-pump-turbine':  { bearing: { ab:2.8, bc:5.3, cd:8.5, unit:'mm\/s RMS' }, shaft: { ab:80, bc:160, cd:260, unit:'\u03bcm p-p' } },\n        'horizontal-pelton':      { bearing: { ab:2.3, bc:4.5, cd:7.1, unit:'mm\/s RMS' }, shaft: { ab:80, bc:160, cd:260, unit:'\u03bcm p-p' } },\n        'vertical-pump':          { bearing: { ab:2.8, bc:5.3, cd:8.5, unit:'mm\/s RMS' }, shaft: { ab:80, bc:160, cd:260, unit:'\u03bcm p-p' } }\n    };\n\n    var ZONE_DESC = {\n        A: 'Newly commissioned machines \u2014 excellent condition',\n        B: 'Acceptable for unrestricted long-term operation',\n        C: 'Not suitable for long-term operation \u2014 plan remedial action',\n        D: 'Dangerous vibration level \u2014 risk of damage, immediate action required'\n    };\n\n    var ZONE_ACTION = {\n        A: 'No action required \u2014 machine in excellent condition',\n        B: 'Continue normal operation and routine monitoring',\n        C: 'Investigate root cause; schedule corrective maintenance; increase monitoring',\n        D: 'Immediate shutdown or load reduction recommended \u2014 risk of damage'\n    };\n\n    function $(id) { return document.getElementById(id); }\n    function fmt(n, d) { if(isNaN(n)) return '\u2014'; var f=n.toFixed(d===undefined?2:d); return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,''); }\n\n    function getZone(val, lim) {\n        if (val <= lim.ab) return 'A';\n        if (val <= lim.bc) return 'B';\n        if (val <= lim.cd) return 'C';\n        return 'D';\n    }\n\n    function calculate() {\n        var machine = $('vc-machine').value;\n        var measurement = $('vc-measurement').value;\n        var val = parseFloat($('vc-value').value);\n\n        if (isNaN(val) || val < 0) {\n            $('vc-results').classList.remove('vc-visible');\n            return;\n        }\n\n        var lim = LIMITS[machine][measurement];\n        var zone = getZone(val, lim);\n\n        ['a','b','c','d'].forEach(function(letter) {\n            var seg = $('zb-' + letter);\n            seg.className = 'vc-zone-bar-seg zb-' + letter + (letter.toUpperCase() === zone ? ' zb-active' : ' zb-dim');\n        });\n\n        $('zl-a').textContent = '\u2264' + lim.ab;\n        $('zl-b').textContent = lim.ab + '\u2013' + lim.bc;\n        $('zl-c').textContent = lim.bc + '\u2013' + lim.cd;\n        $('zl-d').textContent = '>' + lim.cd;\n\n        var zoneCard = $('vc-r-zone-card');\n        zoneCard.className = 'vc-rcard vc-rcard-primary vc-zone-' + zone.toLowerCase();\n        $('vc-r-zone').textContent = 'Zone ' + zone;\n        $('vc-r-zone-desc').textContent = ZONE_DESC[zone];\n\n        $('vc-r-measured').innerHTML = fmt(val, measurement === 'shaft' ? 0 : 2) + ' <span class=\"vc-rcard-unit\">' + lim.unit + '<\/span>';\n        $('vc-r-action').textContent = ZONE_ACTION[zone];\n\n        var tbody = $('vc-boundary-body');\n        tbody.innerHTML =\n            '<tr class=\"zt-a\"><td><strong>Zone A<\/strong><\/td><td>\u2264 ' + lim.ab + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.A + '<\/td><\/tr>' +\n            '<tr class=\"zt-b\"><td><strong>Zone B<\/strong><\/td><td>' + lim.ab + ' \u2013 ' + lim.bc + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.B + '<\/td><\/tr>' +\n            '<tr class=\"zt-c\"><td><strong>Zone C<\/strong><\/td><td>' + lim.bc + ' \u2013 ' + lim.cd + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.C + '<\/td><\/tr>' +\n            '<tr class=\"zt-d\"><td><strong>Zone D<\/strong><\/td><td>&gt; ' + lim.cd + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.D + '<\/td><\/tr>';\n\n        $('vc-results').classList.add('vc-visible');\n\n        var u = new URL(window.location);\n        u.searchParams.set('machine', machine);\n        u.searchParams.set('measurement', measurement);\n        u.searchParams.set('value', val);\n        history.replaceState(null, '', u.toString());\n\n        var machineNames = { 'vertical-kaplan':'Vertical Kaplan', 'vertical-francis':'Vertical Francis', 'vertical-pump-turbine':'Vertical Pump-Turbine', 'horizontal-pelton':'Horizontal Pelton', 'vertical-pump':'Vertical Pump' };\n        var locNames = { bearing:'Bearing housing', shaft:'Shaft displacement' };\n        saveHistory({ machine: machine, measurement: measurement, value: val, zone: zone, _summary: machineNames[machine] + ', ' + locNames[measurement] + ' ' + val + ' ' + lim.unit + ' \u2192 Zone ' + zone });\n    }\n\n    $('vc-measurement').addEventListener('change', function() {\n        $('vc-value-hint').textContent = this.value === 'bearing' ? '(mm\/s RMS)' : '(\u03bcm p-p)';\n        calculate();\n    });\n\n    document.querySelectorAll('.vc-preset-btn').forEach(function(btn) {\n        btn.addEventListener('click', function(e) {\n            e.preventDefault();\n            $('vc-machine').value = this.getAttribute('data-m');\n            $('vc-measurement').value = this.getAttribute('data-l');\n            $('vc-value').value = this.getAttribute('data-v');\n            $('vc-value-hint').textContent = this.getAttribute('data-l') === 'bearing' ? '(mm\/s RMS)' : '(\u03bcm p-p)';\n            calculate();\n        });\n    });\n\n    $('vc-form').addEventListener('input', calculate);\n    $('vc-form').addEventListener('change', calculate);\n\n    $('vc-copy-btn').addEventListener('click', function() {\n        var text = 'Vibration Zone Evaluation \u2014 ISO 20816-5\\n' +\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\n            'Machine: ' + $('vc-machine').options[$('vc-machine').selectedIndex].text + '\\n' +\n            'Measurement: ' + $('vc-measurement').options[$('vc-measurement').selectedIndex].text + '\\n' +\n            'Measured: ' + $('vc-r-measured').textContent + '\\n' +\n            'Zone: ' + $('vc-r-zone').textContent + '\\n' +\n            'Assessment: ' + $('vc-r-zone-desc').textContent + '\\n' +\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\n            'vibromera.eu\/calculators\/vibration-iso20816-5-hydro\/';\n\n        if (navigator.clipboard) {\n            navigator.clipboard.writeText(text).then(function() {\n                var btn = $('vc-copy-btn');\n                btn.classList.add('vc-copied');\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!';\n                setTimeout(function() {\n                    btn.classList.remove('vc-copied');\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';\n                }, 2000);\n            });\n        }\n    });\n\n    document.querySelectorAll('.vc-section-toggle').forEach(function(btn) {\n        btn.addEventListener('click', function() {\n            var section = this.closest('.vc-section');\n            var isOpen = section.classList.contains('vc-open');\n            section.classList.toggle('vc-open');\n            this.setAttribute('aria-expanded', !isOpen);\n        });\n    });\n\n    var faqData = [\n        { q: 'What machines does ISO 20816-5 cover?', a: '<p>ISO 20816-5 applies to <strong>hydraulic machines<\/strong> including:<\/p><ul><li>Vertical Kaplan turbines<\/li><li>Vertical Francis turbines<\/li><li>Vertical pump-turbines (reversible)<\/li><li>Horizontal Pelton turbines<\/li><li>Vertical pumps<\/li><\/ul><p>These machines operate in hydroelectric power plants with typical speeds from 60 to 1000 RPM.<\/p>' },\n        { q: 'Why are hydro turbine vibration limits different from steam turbines?', a: '<p>Hydraulic machines operate at much lower speeds (60\u2013500 RPM vs 1500\u20133600 RPM for steam turbines) and experience unique hydraulic excitation forces:<\/p><ul><li>Draft tube surge and pressure pulsations<\/li><li>Cavitation-induced vibration<\/li><li>Wicket gate and runner vane pass frequencies<\/li><li>Von K\u00e1rm\u00e1n vortex shedding<\/li><\/ul><p>Vertical machines also have additional considerations for thrust bearing vibration and axial hydraulic forces.<\/p>' },\n        { q: 'What is shaft displacement measurement in hydro turbines?', a: '<p>Shaft displacement is measured using <strong>proximity probes<\/strong> mounted near the guide bearings, measuring peak-to-peak displacement in micrometers (\u03bcm p-p). This is critical for vertical machines where shaft orbit monitoring reveals:<\/p><ul><li>Unbalance and misalignment<\/li><li>Hydraulic instabilities<\/li><li>Guide bearing wear<\/li><li>Seal rub conditions<\/li><\/ul>' },\n        { q: 'Why do horizontal Pelton turbines have different limits?', a: '<p>Horizontal Pelton turbines have <strong>lower vibration limits<\/strong> than vertical machines because:<\/p><ul><li>Horizontal bearing arrangements are more sensitive to dynamic forces<\/li><li>Impulse loading from the Pelton bucket jet impact produces distinct vibration<\/li><li>Gravity loads on horizontal bearings create different dynamic behavior<\/li><\/ul><p>The Zone A\/B boundary is 2.3 mm\/s vs 2.8 mm\/s for vertical machines.<\/p>' },\n        { q: 'What should I do if vibration reaches Zone C on a hydro turbine?', a: '<p>For Zone C on a hydro turbine:<\/p><ul><li>Investigate root causes: runner cavitation, draft tube surge, guide bearing wear, shaft misalignment, hydraulic resonance<\/li><li>Increase monitoring frequency to continuous if not already<\/li><li>Consider load restrictions to reduce hydraulic excitation<\/li><li>Plan corrective action during the next scheduled outage<\/li><li>Monitor trend carefully \u2014 if approaching Zone D, consider shutdown<\/li><\/ul>' }\n    ];\n\n    var faqList = $('vc-faq-list');\n    faqData.forEach(function(faq) {\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>';\n    });\n    faqList.addEventListener('click', function(e) {\n        var btn = e.target.closest('.vc-faq-q');\n        if (!btn) return;\n        btn.closest('.vc-faq-item').classList.toggle('vc-open');\n    });\n\n    function saveHistory(entry) {\n        var key = 'vc_history_' + SLUG;\n        var arr = [];\n        try { arr = JSON.parse(localStorage.getItem(key)) || []; } catch(e) {}\n        entry._ts = new Date().toISOString();\n        arr.unshift(entry);\n        if (arr.length > 10) arr = arr.slice(0, 10);\n        try { localStorage.setItem(key, JSON.stringify(arr)); } catch(e) {}\n    }\n\n    function loadParams() {\n        var p = new URLSearchParams(window.location.search);\n        if (p.has('machine')) $('vc-machine').value = p.get('machine');\n        if (p.has('measurement')) {\n            $('vc-measurement').value = p.get('measurement');\n            $('vc-value-hint').textContent = p.get('measurement') === 'bearing' ? '(mm\/s RMS)' : '(\u03bcm p-p)';\n        }\n        if (p.has('value')) $('vc-value').value = p.get('value');\n    }\n\n    function renderFormulas() {\n        try {\n            katex.render('\\\\text{Zone} = \\\\begin{cases} A & v_{\\\\text{meas}} \\\\leq v_{A\/B} \\\\\\\\ B & v_{A\/B} < v_{\\\\text{meas}} \\\\leq v_{B\/C} \\\\\\\\ C & v_{B\/C} < v_{\\\\text{meas}} \\\\leq v_{C\/D} \\\\\\\\ D & v_{\\\\text{meas}} > v_{C\/D} \\\\end{cases}', $('vc-katex-1'), { displayMode: true, throwOnError: false });\n            katex.render('s_{\\\\text{p-p}} = s_{\\\\max} - s_{\\\\min} \\\\quad [\\\\mu m]', $('vc-katex-2'), { displayMode: true, throwOnError: false });\n        } catch(e) {}\n    }\n\n    function init() {\n        loadParams();\n        renderFormulas();\n        calculate();\n    }\n\n    if (document.readyState === 'loading') {\n        document.addEventListener('DOMContentLoaded', init);\n    } else {\n        init();\n    }\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>\u09b9\u09be\u0987\u09a1\u09cd\u09b0\u09b2\u09bf\u0995 \u099f\u09be\u09b0\u09cd\u09ac\u09be\u0987\u09a8, \u09aa\u09be\u09ae\u09cd\u09aa-\u099f\u09be\u09b0\u09cd\u09ac\u09be\u0987\u09a8 \u098f\u09ac\u0982 \u09aa\u09be\u09ae\u09cd\u09aa\u09c7\u09b0 \u099c\u09a8\u09cd\u09af ISO 20816-5 \u0985\u09a8\u09c1\u09af\u09be\u09af\u09bc\u09c0 \u09ac\u09bf\u09a8\u09be\u09ae\u09c2\u09b2\u09cd\u09af\u09c7 \u0985\u09a8\u09b2\u09be\u0987\u09a8 \u09ad\u09be\u0987\u09ac\u09cd\u09b0\u09c7\u09b6\u09a8 \u099c\u09cb\u09a8 \u09ae\u09c2\u09b2\u09cd\u09af\u09be\u09af\u09bc\u09a8 \u0995\u09cd\u09af\u09be\u09b2\u0995\u09c1\u09b2\u09c7\u099f\u09b0\u0964 \u09ac\u09c7\u09af\u09bc\u09be\u09b0\u09bf\u0982 \u09b9\u09be\u0989\u099c\u09bf\u0982 \u09ac\u09c7\u0997 \u098f\u09ac\u0982 \u09b6\u09cd\u09af\u09be\u09ab\u099f\u09cd\u200c \u09b8\u09b0\u09a3 \u099c\u09cb\u09a8 A\/B\/C\/D \u09b8\u09c0\u09ae\u09be\u09b0 \u09ac\u09bf\u09aa\u09b0\u09c0\u09a4\u09c7 \u09ae\u09c2\u09b2\u09cd\u09af\u09be\u09af\u09bc\u09a8 \u0995\u09b0\u09c1\u09a8\u0964<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100289","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100289","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":3,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100289\/revisions"}],"predecessor-version":[{"id":100906,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100289\/revisions\/100906"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/media?parent=100289"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/categories?post=100289"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/tags?post=100289"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}