{"id":100275,"date":"2026-02-15T20:31:27","date_gmt":"2026-02-15T20:31:27","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100275"},"modified":"2026-03-05T15:37:37","modified_gmt":"2026-03-05T15:37:37","slug":"valve-leak-rate-iso5208","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/nb\/calculators\/valve-leak-rate-iso5208\/","title":{"rendered":"Kalkulator for ventillekkasjerate | ISO 5208 klasse A\u2013F"},"content":{"rendered":"\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Valve Leak Rate Calculator\",\"alternateName\":[\"ISO 5208 Calculator\",\"Valve Seat Leakage Calculator\",\"Valve Test Calculator\"],\"description\":\"Free online calculator for maximum permissible valve leak rate per ISO 5208. 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16px;font-size:13px;color:var(--vc-ink-muted)}\n.vc-footer a{color:var(--vc-accent);text-decoration:none}.vc-footer a:hover{text-decoration:underline}\n.vc-footer-links{margin-top:8px;font-size:12px}.vc-footer-links a{margin:0 8px}\n@media print{.vc-section-body{max-height:none!important}.vc-faq-a{max-height:none!important}.vc-results{max-height:none!important;padding:24px!important}.vc-copy-btn,.vc-section-chevron,.vc-faq-chevron,.vc-presets,.vc-promo{display:none!important}}\n<\/style>\n\n<div class=\"vc-calculator\" id=\"vc-valve-leak\">\n\n<header class=\"vc-header\">\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool<\/p>\n    <h1 class=\"vc-header-title\">Valve Leak Rate Calculator<\/h1>\n    <p class=\"vc-header-subtitle\">Determine maximum permissible seat leakage per ISO 5208 for classes A through F. Evaluate pass\/fail based on measured leak rate for liquid and gas testing.<\/p>\n    <div class=\"vc-badges\">\n        <span class=\"vc-badge\">ISO 5208<\/span>\n        <span class=\"vc-badge\">Classes A \u2013 F<\/span>\n        <span class=\"vc-badge\">Liquid &amp; Gas<\/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-dn\">Valve Size (DN) <span class=\"vc-label-hint\">(mm)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-dn\" inputmode=\"decimal\" step=\"any\" min=\"1\" placeholder=\"e.g. 100\" value=\"100\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-pressure\">Test Pressure (\u0394P) <span class=\"vc-label-hint\">(bar)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-pressure\" inputmode=\"decimal\" step=\"any\" min=\"0.01\" placeholder=\"e.g. 16\" value=\"16\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-class\">Leak Rate Class<\/label>\n                <select class=\"vc-select\" id=\"vc-class\">\n                    <option value=\"A\">Class A \u2014 Zero leakage (no visible leak)<\/option>\n                    <option value=\"B\">Class B \u2014 No visible leak at low pressure<\/option>\n                    <option value=\"C\">Class C \u2014 0.0006 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P (liquid)<\/option>\n                    <option value=\"D\" selected>Class D \u2014 0.0018 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P (liquid)<\/option>\n                    <option value=\"E\">Class E \u2014 0.18 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P (gas)<\/option>\n                    <option value=\"F\">Class F \u2014 Special (per manufacturer)<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-fluid\">Test Fluid<\/label>\n                <select class=\"vc-select\" id=\"vc-fluid\">\n                    <option value=\"liquid\" selected>Liquid (water)<\/option>\n                    <option value=\"gas\">Gas (air\/nitrogen)<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-measured\">Measured Leak Rate <span class=\"vc-label-hint\">(ml\/min for liquid, bubbles\/min for gas)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-measured\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 0.5\" value=\"\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-duration\">Test Duration <span class=\"vc-label-hint\">(seconds)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-duration\" inputmode=\"decimal\" step=\"any\" min=\"1\" placeholder=\"e.g. 60\" value=\"60\">\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-dn=\"50\" data-p=\"40\" data-c=\"D\" data-f=\"liquid\">DN50 \/ 40 bar \/ Class D<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-dn=\"150\" data-p=\"16\" data-c=\"D\" data-f=\"liquid\">DN150 \/ 16 bar \/ Class D<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-dn=\"200\" data-p=\"6\" data-c=\"A\" data-f=\"gas\">DN200 \/ 6 bar \/ Class A<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-dn=\"100\" data-p=\"25\" data-c=\"C\" data-f=\"liquid\">DN100 \/ 25 bar \/ Class C<\/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        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\">\n                <div class=\"vc-rcard-label\">Maximum Permissible Leak Rate<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-max\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Leakage Class Description<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-desc\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Recommended Test Duration<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-duration\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\" id=\"vc-r-verdict-card\">\n                <div class=\"vc-rcard-label\">Pass \/ Fail Evaluation<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-verdict\">\u2014<\/div>\n            <\/div>\n        <\/div>\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; Leakage Classes<\/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 5208 Seat Leakage Classes<\/h3>\n            <p>ISO 5208 defines six leakage rate classes (A through F) for industrial valve testing. The permissible leak rate depends on valve size (DN) and test pressure differential (\u0394P).<\/p>\n\n            <table class=\"vc-table\">\n                <thead><tr><th>Class<\/th><th>Liquid Leak Rate<\/th><th>Gas Leak Rate<\/th><th>Description<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td><strong>A<\/strong><\/td><td>Zero<\/td><td>Zero (no visible)<\/td><td>Zero leakage \u2014 no visible leak during test period<\/td><\/tr>\n                    <tr><td><strong>B<\/strong><\/td><td>Zero at low P<\/td><td>Defined by spec<\/td><td>No visible leak at reduced test pressure<\/td><\/tr>\n                    <tr><td><strong>C<\/strong><\/td><td>0.0006 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P<\/td><td>0.06 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P<\/td><td>Low leakage \u2014 stringent process valves<\/td><\/tr>\n                    <tr><td><strong>D<\/strong><\/td><td>0.0018 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P<\/td><td>0.18 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P<\/td><td>Standard leakage \u2014 most common industrial class<\/td><\/tr>\n                    <tr><td><strong>E<\/strong><\/td><td>0.018 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P<\/td><td>1.8 \u00d7 DN\u00b2 \u00d7 \u221a\u0394P<\/td><td>Higher leakage \u2014 less critical applications<\/td><\/tr>\n                    <tr><td><strong>F<\/strong><\/td><td>Special<\/td><td>Special<\/td><td>Manufacturer-defined or customer-specified<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n\n            <h3>Formulas<\/h3>\n            <p>For <strong>liquid<\/strong> testing (water), the permissible leak rate in ml\/min:<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n            <p>For <strong>gas<\/strong> testing (air\/N\u2082), the permissible leak rate in bubbles\/min (or mm\u00b3\/s):<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div>\n\n            <h3>Practical Example<\/h3>\n            <div class=\"vc-example-box\">\n                <div class=\"vc-example-title\">Example \u2014 DN100 Gate Valve, Class D, Liquid Test<\/div>\n                <p><strong>Given:<\/strong> DN = 100 mm, \u0394P = 16 bar, Class D<\/p>\n                <p>Q<sub>max<\/sub> = 0.0018 \u00d7 100\u00b2 \u00d7 \u221a16 = 0.0018 \u00d7 10000 \u00d7 4.0 = <strong>72 ml\/min<\/strong><\/p>\n                <p>If measured leak = 0.5 ml\/min \u2192 <strong>PASS<\/strong> (well within limit)<\/p>\n            <\/div>\n\n            <div class=\"vc-info-box\">\n                <p><strong>\u2139\ufe0f Test Duration:<\/strong> Per ISO 5208, typical test durations depend on valve size. DN \u2264 50: 15 sec, DN 65\u2013200: 60 sec, DN 250\u2013450: 120 sec, DN \u2265 500: 120\u2013300 sec.<\/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 Note:<\/strong> Class A (zero leakage) does not mean mathematically zero \u2014 it means no visible leakage during the specified test duration. Some standards (e.g. API 598) have different leakage class definitions.<\/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\/flange-rating-lookup\/\">Flange Rating Lookup<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/pressure-vessel-en13445\/\">Pressure Vessel (EN 13445)<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/pipe-flexibility-calculator\/\">Pipe Flexibility Calculator<\/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 instruments for vibration diagnostics and field balancing. 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 5208 (Industrial valves \u2014 Pressure testing). Last updated: June 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    function $(id){ return document.getElementById(id); }\n    function fmt(n,d){ if(isNaN(n)||!isFinite(n)) return '\u2014'; var f=n.toFixed(d===undefined?2:d); return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,''); }\n\n    \/\/ Leak rate coefficients: { liquid: coeff, gas: coeff }\n    var classCoeffs = {\n        A: { liquid: 0, gas: 0, desc: 'Zero leakage (no visible leak)' },\n        B: { liquid: 0, gas: 0, desc: 'No visible leak at reduced pressure' },\n        C: { liquid: 0.0006, gas: 0.06, desc: 'Low leakage \u2014 stringent process valves' },\n        D: { liquid: 0.0018, gas: 0.18, desc: 'Standard leakage \u2014 most common industrial' },\n        E: { liquid: 0.018, gas: 1.8, desc: 'Higher leakage \u2014 less critical services' },\n        F: { liquid: 0, gas: 0, desc: 'Special \u2014 manufacturer\/customer defined' }\n    };\n\n    \/\/ Test duration by DN (seconds)\n    function getTestDuration(dn) {\n        if (dn <= 50) return 15;\n        if (dn <= 200) return 60;\n        if (dn <= 450) return 120;\n        return 300;\n    }\n\n    function calculate() {\n        var dn = parseFloat($('vc-dn').value);\n        var dp = parseFloat($('vc-pressure').value);\n        var cls = $('vc-class').value;\n        var fluid = $('vc-fluid').value;\n        var measured = parseFloat($('vc-measured').value);\n\n        if (!dn || dn <= 0 || !dp || dp <= 0) {\n            $('vc-results').classList.remove('vc-visible');\n            return;\n        }\n\n        var coeff = classCoeffs[cls];\n        var k = fluid === 'liquid' ? coeff.liquid : coeff.gas;\n        var qMax;\n        var unit = fluid === 'liquid' ? 'ml\/min' : 'bubbles\/min';\n\n        if (cls === 'A' || cls === 'B') {\n            qMax = 0;\n        } else if (cls === 'F') {\n            qMax = NaN;\n        } else {\n            qMax = k * dn * dn * Math.sqrt(dp);\n        }\n\n        \/\/ Display\n        if (cls === 'A' || cls === 'B') {\n            $('vc-r-max').innerHTML = '<span style=\"color:var(--vc-green)\">ZERO<\/span> <span class=\"vc-rcard-unit\">(no visible leak)<\/span>';\n        } else if (cls === 'F') {\n            $('vc-r-max').innerHTML = 'Per manufacturer spec';\n        } else {\n            $('vc-r-max').innerHTML = fmt(qMax, qMax < 1 ? 4 : 2) + ' <span class=\"vc-rcard-unit\">' + unit + '<\/span>';\n        }\n\n        $('vc-r-desc').innerHTML = '<span style=\"font-size:16px\">' + coeff.desc + '<\/span>';\n\n        var recDur = getTestDuration(dn);\n        $('vc-r-duration').innerHTML = recDur + ' <span class=\"vc-rcard-unit\">seconds<\/span> <span class=\"vc-rcard-unit\">(for DN ' + dn + ')<\/span>';\n\n        \/\/ Pass\/Fail\n        var card = $('vc-r-verdict-card');\n        card.className = 'vc-rcard';\n        if (!isNaN(measured) && measured >= 0) {\n            if (cls === 'A' || cls === 'B') {\n                if (measured === 0) {\n                    $('vc-r-verdict').innerHTML = '<span style=\"color:var(--vc-green);font-size:28px;\">\u2713 PASS<\/span>';\n                    card.className = 'vc-rcard vc-rcard-pass';\n                } else {\n                    $('vc-r-verdict').innerHTML = '<span style=\"color:var(--vc-red);font-size:28px;\">\u2717 FAIL<\/span> <span class=\"vc-rcard-unit\">(any visible leak = fail)<\/span>';\n                    card.className = 'vc-rcard vc-rcard-fail';\n                }\n            } else if (cls !== 'F') {\n                if (measured <= qMax) {\n                    $('vc-r-verdict').innerHTML = '<span style=\"color:var(--vc-green);font-size:28px;\">\u2713 PASS<\/span> <span class=\"vc-rcard-unit\">(' + fmt(measured,2) + ' \u2264 ' + fmt(qMax,2) + ' ' + unit + ')<\/span>';\n                    card.className = 'vc-rcard vc-rcard-pass';\n                } else {\n                    $('vc-r-verdict').innerHTML = '<span style=\"color:var(--vc-red);font-size:28px;\">\u2717 FAIL<\/span> <span class=\"vc-rcard-unit\">(' + fmt(measured,2) + ' > ' + fmt(qMax,2) + ' ' + unit + ')<\/span>';\n                    card.className = 'vc-rcard vc-rcard-fail';\n                }\n            } else {\n                $('vc-r-verdict').innerHTML = 'Compare to manufacturer spec';\n            }\n        } else {\n            $('vc-r-verdict').innerHTML = '<span class=\"vc-rcard-unit\">Enter measured leak rate above<\/span>';\n        }\n\n        $('vc-results').classList.add('vc-visible');\n    }\n\n    \/* \u2500\u2500 PRESETS \u2500\u2500 *\/\n    document.querySelectorAll('.vc-preset-btn').forEach(function(btn){\n        btn.addEventListener('click', function(e){\n            e.preventDefault();\n            $('vc-dn').value = this.getAttribute('data-dn');\n            $('vc-pressure').value = this.getAttribute('data-p');\n            $('vc-class').value = this.getAttribute('data-c');\n            $('vc-fluid').value = this.getAttribute('data-f');\n            calculate();\n        });\n    });\n\n    $('vc-form').addEventListener('input', calculate);\n    $('vc-form').addEventListener('change', calculate);\n\n    \/* \u2500\u2500 COPY \u2500\u2500 *\/\n    $('vc-copy-btn').addEventListener('click', function(){\n        var text = 'Valve Leak Rate Calculation (ISO 5208)\\n\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\n            'DN: ' + $('vc-dn').value + ' mm\\n' +\n            'Test Pressure: ' + $('vc-pressure').value + ' bar\\n' +\n            'Class: ' + $('vc-class').value + '\\n' +\n            'Fluid: ' + $('vc-fluid').options[$('vc-fluid').selectedIndex].text + '\\n' +\n            'Max Leak Rate: ' + $('vc-r-max').textContent + '\\n' +\n            'Verdict: ' + $('vc-r-verdict').textContent + '\\n' +\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\nvibromera.eu\/calculators\/valve-leak-rate-iso5208\/';\n        if(navigator.clipboard){\n            navigator.clipboard.writeText(text).then(function(){\n                var btn=$('vc-copy-btn'); 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(){ btn.classList.remove('vc-copied'); 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'; },2000);\n            });\n        }\n    });\n\n    \/* \u2500\u2500 SECTIONS \u2500\u2500 *\/\n    document.querySelectorAll('.vc-section-toggle').forEach(function(btn){\n        btn.addEventListener('click', function(){\n            var s=this.closest('.vc-section'); s.classList.toggle('vc-open');\n            this.setAttribute('aria-expanded', s.classList.contains('vc-open'));\n        });\n    });\n\n    \/* \u2500\u2500 FAQ \u2500\u2500 *\/\n    var faqData = [\n        { q:'What is ISO 5208?', a:'<p>ISO 5208 (Industrial valves \u2014 Pressure testing of metallic valves) defines the requirements for pressure testing of industrial valves, including shell and seat tests. It specifies six seat leakage rate classes (A through F) with defined acceptance criteria.<\/p>' },\n        { q:'What is the difference between Class A and Class D?', a:'<p><strong>Class A<\/strong> requires zero visible leakage \u2014 the most stringent requirement, used for critical services (toxic, flammable fluids). <strong>Class D<\/strong> allows a calculated leak rate based on DN and \u0394P \u2014 the most commonly specified industrial class, suitable for general process applications.<\/p>' },\n        { q:'How is the leak rate formula derived?', a:'<p>The formula Q = k \u00d7 DN\u00b2 \u00d7 \u221a\u0394P is empirical and accounts for the fact that larger valves (proportional to DN\u00b2) and higher pressures (proportional to \u221a\u0394P) naturally allow proportionally more leakage. The coefficient k varies by class and fluid type.<\/p>' },\n        { q:'What is the difference between ISO 5208 and API 598?', a:'<p>Both standards cover valve pressure testing. ISO 5208 defines six classes (A\u2013F) with formulas. API 598 uses a simpler approach with allowable leak rates per inch of DN. API 598 is widely used in North America, ISO 5208 internationally.<\/p>' },\n        { q:'Can gas and liquid leak rates be compared?', a:'<p>Not directly. Gas leakage is measured in bubbles\/min (or mm\u00b3\/s at standard conditions), while liquid leakage is in ml\/min (or drops). The coefficients differ by a factor of ~100 between liquid and gas for the same class due to the different viscosities and surface tensions.<\/p>' }\n    ];\n    var faqList = $('vc-faq-list');\n    faqData.forEach(function(faq){ 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    faqList.addEventListener('click', function(e){ var btn=e.target.closest('.vc-faq-q'); if(btn) btn.closest('.vc-faq-item').classList.toggle('vc-open'); });\n\n    \/* \u2500\u2500 KATEX \u2500\u2500 *\/\n    function renderFormulas(){\n        try{\n            katex.render('Q_{\\\\text{liquid}} = k \\\\times DN^2 \\\\times \\\\sqrt{\\\\Delta P} \\\\quad [\\\\text{ml\/min}]', $('vc-katex-1'), {displayMode:true,throwOnError:false});\n            katex.render('Q_{\\\\text{gas}} = k_g \\\\times DN^2 \\\\times \\\\sqrt{\\\\Delta P} \\\\quad [\\\\text{bubbles\/min}]', $('vc-katex-2'), {displayMode:true,throwOnError:false});\n        }catch(e){}\n    }\n\n    function init(){\n        renderFormulas();\n        calculate();\n    }\n    if(document.readyState==='loading') document.addEventListener('DOMContentLoaded',init); else init();\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Gratis kalkulator for ventillekkasjerate p\u00e5 nett i henhold til ISO 5208. Bestem maksimal tillatt lekkasje for ventilsetelekkasjeklasse A til F. Evaluer best\u00e5tt\/ikke best\u00e5tt for v\u00e6ske- og gasstesting.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100275","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100275","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":2,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100275\/revisions"}],"predecessor-version":[{"id":100750,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100275\/revisions\/100750"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/media?parent=100275"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/categories?post=100275"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/tags?post=100275"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}