{"id":100134,"date":"2026-02-15T20:19:35","date_gmt":"2026-02-15T20:19:35","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100134"},"modified":"2026-07-12T14:20:12","modified_gmt":"2026-07-12T14:20:12","slug":"hydraulic-valve-cetop-iso4401","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/zh\/calculators\/hydraulic-valve-cetop-iso4401\/","title":{"rendered":"Documented Valve-Path Flow Coefficient &#038; Pressure-Drop Calculator"},"content":{"rendered":"\r\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Documented Valve-Path Flow Coefficient and Pressure-Drop Calculator\",\"description\":\"Derive an effective liquid valve-path coefficient from a documented flow\/pressure-drop point or predict pressure drop from a sourced coefficient, with explicit Kv, hydraulic L\/min and US Cv 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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}}.vc-doc-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}.vc-wide{grid-column:1\/-1}.vc-result-note{font-size:13px;color:var(--vc-ink-secondary);margin:0}@media(max-width:600px){.vc-doc-grid{grid-template-columns:1fr}.vc-wide{grid-column:auto}}.vc-doc-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px}.vc-wide{grid-column:1\/-1}.vc-hidden{display:none!important}.vc-formula-box{font-family:var(--vc-mono);background:var(--vc-surface-alt);border:1px solid var(--vc-border-light);border-radius:6px;padding:14px;margin:12px 0;line-height:1.75}.vc-result-note{font-size:13px;color:var(--vc-ink-secondary);margin:0}@media(max-width:650px){.vc-doc-grid{grid-template-columns:1fr}.vc-wide{grid-column:auto}}<\/style>\r\n<div class=\"vc-calculator\" id=\"vc-valve-path\"><header class=\"vc-header\"><p class=\"vc-header-eyebrow\">One documented liquid path and operating state<\/p><h1 class=\"vc-header-title\">Documented Valve-Path Flow Coefficient &amp; Pressure-Drop Calculator<\/h1><p class=\"vc-header-subtitle\">Derive an effective coefficient from a documented Q\u2013\u0394p point, or predict \u0394p from a sourced coefficient, for one identified valve path and opening. ISO 4401 mounting-interface designation is recorded but never used as a flow-capacity selector.<\/p><div class=\"vc-badges\"><span class=\"vc-badge\">Explicit coefficient convention<\/span><span class=\"vc-badge\">Path-specific Q\u2013\u0394p<\/span><span class=\"vc-badge\">No CETOP auto-sizing<\/span><\/div><\/header>\r\n<div class=\"vc-card\"><form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\"><div class=\"vc-doc-grid\"><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-id\">Calculation \/ test identifier<\/label><input class=\"vc-input\" id=\"vc-id\" type=\"text\" maxlength=\"220\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-product\">Valve product \/ model<\/label><input class=\"vc-input\" id=\"vc-product\" type=\"text\" maxlength=\"500\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-path\">Flow path, spool\/element state and opening<\/label><input class=\"vc-input\" id=\"vc-path\" type=\"text\" maxlength=\"600\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-data-source\">Product curve, test report or datasheet source \/ revision<\/label><input class=\"vc-input\" id=\"vc-data-source\" type=\"text\" maxlength=\"700\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-interface\">Documented mounting-interface designation<\/label><input class=\"vc-input\" id=\"vc-interface\" type=\"text\" maxlength=\"250\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-interface-source\">Interface drawing \/ controlled source<\/label><input class=\"vc-input\" id=\"vc-interface-source\" type=\"text\" maxlength=\"600\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-mode\">Calculation mode<\/label><select class=\"vc-select\" id=\"vc-mode\"><option value=\"\">Select\u2026<\/option><option value=\"derive\">Derive effective coefficient from Q and measured\/published \u0394p<\/option><option value=\"predict\">Predict \u0394p from a documented coefficient<\/option><\/select><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-qunit\">Flow unit<\/label><select class=\"vc-select\" id=\"vc-qunit\"><option value=\"\">Select\u2026<\/option><option value=\"lmin\">L\/min<\/option><option value=\"m3h\">m\u00b3\/h<\/option><option value=\"usgpm\">US gal\/min<\/option><\/select><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-q\">Volume flow Q<\/label><input class=\"vc-input\" id=\"vc-q\" type=\"text\" inputmode=\"decimal\" maxlength=\"80\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-punit\">Differential-pressure unit<\/label><select class=\"vc-select\" id=\"vc-punit\"><option value=\"\">Select\u2026<\/option><option value=\"bar\">bar<\/option><option value=\"kpa\">kPa<\/option><option value=\"mpa\">MPa<\/option><option value=\"psi\">psi<\/option><\/select><\/div><div class=\"vc-field\" id=\"vc-dp-field\"><label class=\"vc-label\" for=\"vc-dp\">Measured\/published path differential pressure \u0394p<\/label><input class=\"vc-input\" id=\"vc-dp\" type=\"text\" inputmode=\"decimal\" maxlength=\"80\"><\/div><div class=\"vc-field\" id=\"vc-dp-source-field\"><label class=\"vc-label\" for=\"vc-dp-source\">Q\u2013\u0394p test\/curve conditions and reading source<\/label><input class=\"vc-input\" id=\"vc-dp-source\" type=\"text\" maxlength=\"700\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-sg\">Liquid specific gravity SG <span class=\"vc-label-hint\">(dimensionless)<\/span><\/label><input class=\"vc-input\" id=\"vc-sg\" type=\"text\" inputmode=\"decimal\" maxlength=\"80\"><\/div><div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-sg-source\">Density\/SG source, reference water basis and temperature<\/label><input class=\"vc-input\" id=\"vc-sg-source\" type=\"text\" maxlength=\"700\"><\/div><div class=\"vc-field\" id=\"vc-cunit-field\"><label class=\"vc-label\" for=\"vc-cunit\">Documented coefficient convention<\/label><select class=\"vc-select\" id=\"vc-cunit\"><option value=\"\">Select\u2026<\/option><option value=\"kv\">Kv(bar): m\u00b3\/h at 1 bar, SG=1<\/option><option value=\"kl\">Hydraulic K\u2097: L\/min at 1 bar, SG=1<\/option><option value=\"cv\">Cv(US): US gal\/min at 1 psi, SG=1<\/option><\/select><\/div><div class=\"vc-field\" id=\"vc-coeff-field\"><label class=\"vc-label\" for=\"vc-coeff\">Documented coefficient value<\/label><input class=\"vc-input\" id=\"vc-coeff\" type=\"text\" inputmode=\"decimal\" maxlength=\"80\"><\/div><div class=\"vc-field vc-wide\" id=\"vc-coeff-source-field\"><label class=\"vc-label\" for=\"vc-coeff-source\">Coefficient source, convention, path\/opening and test conditions<\/label><input class=\"vc-input\" id=\"vc-coeff-source\" type=\"text\" maxlength=\"800\"><\/div><div class=\"vc-field vc-wide\"><label class=\"vc-label\" for=\"vc-review\">Viscosity, temperature, cavitation, Reynolds-regime, pressure-rating and system review<\/label><input class=\"vc-input\" id=\"vc-review\" type=\"text\" maxlength=\"900\"><\/div><\/div><p id=\"vc-error\" role=\"alert\" style=\"margin:.75rem 0 0;color:#b42318\"><\/p><div class=\"vc-warning-box\"><p style=\"margin:0\"><strong>Applicability gate:<\/strong> incompressible single-phase liquid, steady fixed path\/opening and a square-root turbulent-flow coefficient applicable to the entered state. The effective coefficient can change with spool position, path, Reynolds number, viscosity, temperature, cavitation\/aeration and measurement method. Use the manufacturer\u2019s actual \u0394p\u2013Q curve whenever available.<\/p><\/div><\/form>\r\n<div class=\"vc-results\" id=\"vc-results\" aria-live=\"polite\"><div class=\"vc-results-head\"><h2 class=\"vc-results-title\">Documented valve-path result<\/h2><button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\">Copy<\/button><\/div><div class=\"vc-result-grid\"><div class=\"vc-rcard vc-rcard-primary\"><div class=\"vc-rcard-label\">Path differential pressure \u0394p<\/div><div class=\"vc-rcard-value\" id=\"vc-r-dp\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Normalized flow<\/div><div class=\"vc-rcard-value\" id=\"vc-r-q\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Standard metric Kv(bar)<\/div><div class=\"vc-rcard-value\" id=\"vc-r-kv\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Hydraulic K\u2097<\/div><div class=\"vc-rcard-value\" id=\"vc-r-kl\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">US Cv<\/div><div class=\"vc-rcard-value\" id=\"vc-r-cv\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Steady fluid-power drop Q\u0394p<\/div><div class=\"vc-rcard-value\" id=\"vc-r-power\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Calculation mode<\/div><div class=\"vc-rcard-value\" id=\"vc-r-mode\">\u2014<\/div><\/div><div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Interface role<\/div><div class=\"vc-rcard-value\" id=\"vc-r-interface\">\u2014<\/div><\/div><\/div><p class=\"vc-result-note\" id=\"vc-r-note\"><\/p><\/div><\/div>\r\n<div class=\"vc-section vc-open\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udcd8<\/span><span class=\"vc-section-title\">Equations, conventions and ISO boundary<\/span><\/span><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner vc-theory\"><h3>Implemented liquid coefficient model<\/h3><div class=\"vc-formula-box\">Q(m\u00b3\/h) = Kv \u221a(\u0394p(bar)\/SG)<br>Kv = Q \u221a(SG\/\u0394p)<br>\u0394p(bar) = SG [Q\/Kv]\u00b2<br>K\u2097(L\/min\/\u221abar) = Kv\/0.06<br>Cv(US) = 1.15609922835 Kv<br>Pdrop(kW) = Q(L\/min) \u0394p(bar) \/ 600<\/div><p>The subscripted conventions are deliberate. Parker\u2019s hydraulic technical guide uses a coefficient in L\/min at 1 bar; Spirax Sarco describes the standard bar-based metric Kv in m\u00b3\/h and warns that multiple Kv\/Cv conventions exist. Never paste an unlabelled coefficient into a different convention.<\/p><h3>Published numerical example<\/h3><p><a href=\"https:\/\/www.spiraxsarco.com\/learn-about-steam\/control-hardware-electric-pneumatic-actuation\/control-valve-sizing-for-water-systems\" target=\"_blank\" rel=\"noopener\">Spirax Sarco Example 6.3.1<\/a> uses 10 m\u00b3\/h water and Kv=16. The implemented equation predicts \u0394p=(10\/16)\u00b2=0.390625 bar, matching the published approximately 0.4 bar.<\/p><h3>ISO 4401 mounting-interface boundary<\/h3><p><a href=\"https:\/\/www.iso.org\/standard\/33366.html\" target=\"_blank\" rel=\"noopener\">ISO 4401:2005<\/a>, edition 3, is Published and was confirmed in 2022. It specifies dimensions and other data for interchangeable mounting surfaces of four-port directional control valves; it does not assign a universal flow range, internal port diameter, Kv, pressure rating or pressure-drop curve. Exact mounting dimensions remain <strong>NEEDS_LICENSED_SOURCE<\/strong> and are not reproduced here.<\/p><h3>Pressure-drop characteristic boundary<\/h3><p><a href=\"https:\/\/www.iso.org\/standard\/67811.html\" target=\"_blank\" rel=\"noopener\">ISO 4411:2019<\/a>, edition 3, Published and confirmed in 2024, specifies steady-state methods for determining differential-pressure\/flow characteristics for a given valve path. The exact test procedure is not reproduced. Product curves remain path, spool, opening, fluid and temperature specific. For example, <a href=\"https:\/\/www.parker.com\/content\/dam\/Parker-com\/Literature\/Industrial-Systems-Division-Europe\/Catalogues\/Industrial-Valves-UK\/07\/CM-UK.pdf\" target=\"_blank\" rel=\"noopener\">Parker CM catalogue<\/a> gives different product-specific maximum flows and \u0394p\u2013Q curves for NG06 and NG10 interfaces and states the test viscosity; those values are not universal interface limits.<\/p><h3>Why the former page was changed<\/h3><p>The former page could dereference an undefined CETOP record and crash on load (`portDia`). It automatically chose a mounting-interface size from fabricated universal flow bands, published unsupported port\/thread\/bolt\/face\/Kv tables and computed velocity from invented port diameters. It also implied that ISO 4401 supplied the flow formula, defaulted Q\/\u0394p\/SG, accepted numeric prefixes and called Q\u0394p a guaranteed cooler heat load.<\/p><div class=\"vc-warning-box\"><p style=\"margin:0\"><strong>No valve or cooler selection:<\/strong> verify exact product\/interface drawing, path and spool state, pressure\/flow curve, rated pressure and tank-port limits, leakage, hysteresis, dynamics, viscosity\/temperature range, contamination requirement, cavitation\/aeration, actuator load and system transients. Q\u0394p is the steady fluid-power decrease across the entered path, not by itself a cooler duty or proof of suitability.<\/p><\/div><\/div><\/div><\/div><footer class=\"vc-footer\"><p>\u00a9 2024\u20132026 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a><\/p><p>Documented single-path coefficient arithmetic only. Scientific review: July 2026.<\/p><\/footer><\/div>\r\n<script>(function(){'use strict';function $(id){return document.getElementById(id)}var map={vp_id:'vc-id',vp_product:'vc-product',vp_path:'vc-path',vp_data_source:'vc-data-source',vp_interface:'vc-interface',vp_interface_source:'vc-interface-source',vp_mode:'vc-mode',vp_qunit:'vc-qunit',vp_q:'vc-q',vp_punit:'vc-punit',vp_dp:'vc-dp',vp_dp_source:'vc-dp-source',vp_sg:'vc-sg',vp_sg_source:'vc-sg-source',vp_cunit:'vc-cunit',vp_coeff:'vc-coeff',vp_coeff_source:'vc-coeff-source',vp_review:'vc-review'};var qf={lmin:.06,m3h:1,usgpm:.22712470704},pf={bar:1,kpa:.01,mpa:10,psi:1\/14.503773773020923},ql={lmin:'L\/min',m3h:'m\u00b3\/h',usgpm:'US gal\/min'},pl={bar:'bar',kpa:'kPa',mpa:'MPa',psi:'psi'},cvpkv=1.1560992283536566;function num(raw){var s=String(raw).trim().replace(',','.');if(s.length>80||!\/^[-+]?(?:\\d+(?:\\.\\d*)?|\\.\\d+)(?:[eE][+-]?\\d+)?$\/.test(s))return NaN;return Number(s)}function 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