{"id":27682,"date":"2025-12-17T06:52:12","date_gmt":"2025-12-17T06:52:12","guid":{"rendered":"https:\/\/metlaninst.com\/?p=27682"},"modified":"2026-01-14T08:39:35","modified_gmt":"2026-01-14T08:39:35","slug":"pipe-flow-vs-pressure-relationship-and-how-to-calculate","status":"publish","type":"post","link":"https:\/\/metlaninst.com\/fr\/pipe-flow-vs-pressure-relationship-and-how-to-calculate\/","title":{"rendered":"Pipe Flow vs Pressure: Relationship and How to Calculate"},"content":{"rendered":"<p>In fluid systems, few topics are as fundamental\u2014and as frequently misunderstood\u2014as the relationship between <strong>flow<\/strong> et <strong>pression<\/strong> in a pipe. Engineers often hear statements like <em>\u201chigher pressure means higher flow\u201d<\/em> ou <em>\u201clow pressure causes low flow\u201d<\/em>, yet in real pipeline systems, the relationship is far more nuanced.<\/p><p>Accurate understanding of <strong>pipe flow vs pressure<\/strong> is essential for designing pipelines, selecting pumps and compressors, choosing flow meters, diagnosing system problems, and ensuring safe, efficient operation across industries such as oil &amp; gas, water treatment, chemical processing, energy, and manufacturing.<\/p><div class=\"wp-block-rank-math-toc-block\" id=\"rank-math-toc\"><h2>Table des mati\u00e8res<\/h2><nav><ul><li><a href=\"#what-is-pressure\">What Is Pressure?<\/a><\/li><li><a href=\"#what-is-flow\">What Is Flow?<\/a><\/li><li><a href=\"#what-is-pipe-diameter\">What Is Pipe Diameter?<\/a><\/li><li><a href=\"#importance-of-monitoring-pipeline-pressure-and-flow\">Importance of Monitoring Pipeline Pressure and Flow<\/a><\/li><li><a href=\"#relationship-between-flow-and-pressure\">Relationship Between Flow and Pressure<\/a><\/li><li><a href=\"#online-calculation-tool\">Online Calculation Tool<\/a><\/li><\/ul><\/nav><\/div><h2 class=\"wp-block-heading\" id=\"what-is-pressure\"><strong>What Is Pressure?<\/strong><\/h2><p><strong>Pression<\/strong> is the force exerted by a fluid per unit area on the walls of a container or pipe.<\/p><p>P=F\/A<\/p><p>O\u00f9 ?<\/p><ul class=\"wp-block-list\"><li>PPP = pressure<\/li>\n\n<li>FFF = force<\/li>\n\n<li>AAA = area<\/li><\/ul><h3 class=\"wp-block-heading\" id=\"common-units-of-pressure\"><strong>Common Units of Pressure<\/strong><\/h3><ul class=\"wp-block-list\"><li>Pascal (Pa)<\/li>\n\n<li>bar<\/li>\n\n<li>psi (pounds per square inch)<\/li>\n\n<li>MPa<\/li><\/ul><h3 class=\"wp-block-heading\" id=\"types-of-pressure-in-pipe-systems\"><strong>Types of Pressure in Pipe Systems<\/strong><\/h3><ul class=\"wp-block-list\"><li><strong>Static pressure<\/strong> \u2013 pressure at rest<\/li>\n\n<li><strong>Dynamic pressure<\/strong> \u2013 pressure associated with fluid velocity<\/li>\n\n<li><strong>Differential pressure (\u0394P)<\/strong> \u2013 pressure drop between two points<\/li>\n\n<li><strong>Gauge pressure<\/strong> \u2013 pressure relative to atmosphere<\/li>\n\n<li><strong>Absolute pressure<\/strong> \u2013 pressure relative to vacuum<\/li><\/ul><p>In pipelines, pressure serves primarily as the <strong>driving force<\/strong> that overcomes resistance and moves fluid from one point to another.<\/p><h2 class=\"wp-block-heading\" id=\"what-is-flow\"><strong>What Is Flow?<\/strong><\/h2><p><strong>Flow<\/strong> describes how much fluid moves through a pipe over time. Typically, flow can be expressed in terms of volume flow or <a href=\"https:\/\/metlaninst.com\/fr\/comprendre-les-notions-de-debit-massique-et-de-debit-volumetrique\/\" target=\"_blank\" data-type=\"post\" data-id=\"27531\" rel=\"noreferrer noopener\">d\u00e9bit massique<\/a>.<br>Volume flow refers to the volume of fluid flowing through a pipe cross-section per unit time, usually expressed in units such as cubic meters per second (m\u00b3\/s) or cubic meters per hour (m\u00b3\/h).<br>Mass flow refers to the mass of fluid flowing through a pipe section per unit time, usually expressed in units such as kilograms per second (kg\/s).<\/p><h2 class=\"wp-block-heading\" id=\"what-is-pipe-diameter\"><strong>What Is Pipe Diameter?<\/strong><\/h2><p><strong>Pipe diameter<\/strong> determines the cross-sectional area available for flow and is one of the most influential variables in pipeline behavior.<\/p><h3 class=\"wp-block-heading\" id=\"why-pipe-diameter-matters\"><strong>Why Pipe Diameter Matters<\/strong><\/h3><ul class=\"wp-block-list\"><li>Larger diameter \u2192 lower velocity for the same flow<\/li>\n\n<li>Lower velocity \u2192 lower friction losses<\/li>\n\n<li>Small diameter changes can cause <strong>large pressure drop changes<\/strong><\/li><\/ul><p>In fact, pipe diameter has a <strong>non-linear effect<\/strong> on pressure loss, making it a critical design variable.<\/p><h3 class=\"wp-block-heading\" id=\"pipe-diameter-conversion-table\">Pipe Diameter<strong>&nbsp;Conversion Table<\/strong><\/h3><table class=\"pipe-dn-table\" aria-label=\"Pipe Diameter Conversion Table (NPS to DN)\">\n  <thead>\n    <tr>\n      <th>NPS (Nominal Pipe Size &#8211; in Inches)<\/th>\n      <th>DN (Nominal Diameter &#8211; in Millimeters)<\/th>\n    <\/tr>\n  <\/thead>\n  <tbody>\n    <tr><td>1\/8&#8243;<\/td><td>6<\/td><\/tr>\n    <tr><td>1\/4&#8243;<\/td><td>8<\/td><\/tr>\n    <tr><td>3\/8&#8243;<\/td><td>10<\/td><\/tr>\n    <tr><td>1\/2&#8243;<\/td><td>15<\/td><\/tr>\n    <tr><td>3\/4&#8243;<\/td><td>20<\/td><\/tr>\n    <tr><td>1&#8243;<\/td><td>25<\/td><\/tr>\n    <tr><td>1 1\/4&#8243;<\/td><td>32<\/td><\/tr>\n    <tr><td>1 1\/2&#8243;<\/td><td>40<\/td><\/tr>\n    <tr><td>2&#8243;<\/td><td>50<\/td><\/tr>\n    <tr><td>2 1\/2&#8243;<\/td><td>65<\/td><\/tr>\n    <tr><td>3&#8243;<\/td><td>80<\/td><\/tr>\n    <tr><td>3 1\/2&#8243;<\/td><td>90<\/td><\/tr>\n    <tr><td>4&#8243;<\/td><td>100<\/td><\/tr>\n    <tr><td>5&#8243;<\/td><td>125<\/td><\/tr>\n    <tr><td>6&#8243;<\/td><td>150<\/td><\/tr>\n    <tr><td>8&#8243;<\/td><td>200<\/td><\/tr>\n    <tr><td>10&#8243;<\/td><td>250<\/td><\/tr>\n    <tr><td>12&#8243;<\/td><td>300<\/td><\/tr>\n    <tr><td>14&#8243;<\/td><td>350<\/td><\/tr>\n    <tr><td>16&#8243;<\/td><td>400<\/td><\/tr>\n    <tr><td>18&#8243;<\/td><td>450<\/td><\/tr>\n    <tr><td>20&#8243;<\/td><td>500<\/td><\/tr>\n    <tr><td>24&#8243;<\/td><td>600<\/td><\/tr>\n  <\/tbody>\n<\/table>\n\n<p class=\"pipe-dn-note\">\n  Note: NPS and DN are nominal sizes; actual pipe OD\/ID may vary by standard and schedule.\n<\/p><h2 class=\"wp-block-heading\" id=\"importance-of-monitoring-pipeline-pressure-and-flow\"><strong>Importance of Monitoring Pipeline Pressure and Flow<\/strong><\/h2><p>Monitoring <strong>both pressure and flow<\/strong>\u2014not just one\u2014is essential for system performance and safety.<\/p><h3 class=\"wp-block-heading\" id=\"why-pressure-monitoring-is-critical\"><strong>Why Pressure Monitoring Is Critical<\/strong><\/h3><ul class=\"wp-block-list\"><li>Detects blockages or fouling<\/li>\n\n<li>Prevents over-pressure damage<\/li>\n\n<li>Ensures pump and compressor protection<\/li>\n\n<li>Indicates leaks or valve malfunctions<\/li><\/ul><h3 class=\"wp-block-heading\" id=\"why-flow-monitoring-is-critical\"><strong>Why Flow Monitoring Is Critical<\/strong><\/h3><ul class=\"wp-block-list\"><li>Confirms actual throughput<\/li>\n\n<li>Supports custody transfer and billing<\/li>\n\n<li>Enables process control and batching<\/li>\n\n<li>Detects production losses<\/li><\/ul><h3 class=\"wp-block-heading\" id=\"why-pressure-alone-is-not-enough\"><strong>Why Pressure Alone Is Not Enough<\/strong><\/h3><p>High pressure does <strong>not<\/strong> guarantee high flow. A blocked or closed pipeline can show high pressure but zero flow. Likewise, high flow may exist at relatively low pressure if resistance is low.<\/p><h2 class=\"wp-block-heading\" id=\"relationship-between-flow-and-pressure\"><strong>Relationship Between Flow and Pressure<\/strong><\/h2><p>The relationship between flow and pressure in a pipe is governed by fundamental physical laws. While many simplified explanations exist, in engineering practice <strong>three core relationships matter the most<\/strong>:<\/p><ol class=\"wp-block-list\"><li><strong>Bernoulli\u2019s Equation<\/strong> \u2013 energy conversion between pressure and velocity<\/li>\n\n<li><strong>Darcy\u2013Weisbach Equation<\/strong> \u2013 pressure loss due to friction (real pipelines)<\/li>\n\n<li><strong>Poiseuille\u2019s Law<\/strong> \u2013 flow\u2013pressure relationship in laminar, viscous flow<\/li><\/ol><p>Understanding these three principles allows engineers to correctly predict how flow responds to pressure changes in almost all pipeline systems.<\/p><h3 class=\"wp-block-heading\" id=\"bernoullis-equation-pressure-vs-velocity-energy-perspective\"><strong>Bernoulli\u2019s Equation \u2014 Pressure vs Velocity (Energy Perspective)<\/strong><\/h3><div class=\"wp-block-media-text is-stacked-on-mobile\"><figure class=\"wp-block-media-text__media\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1024\" height=\"914\" src=\"http:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity-1024x914.webp\" alt=\"Bernoulli\u2019s Equation Pressure vs Velocity\" class=\"wp-image-27683 size-full\" srcset=\"https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity-1024x914.webp 1024w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity-300x268.webp 300w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity-768x685.webp 768w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity-340x303.webp 340w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity-13x12.webp 13w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity-1000x892.webp 1000w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity-1300x1160.webp 1300w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Bernoullis-Equation-Pressure-vs-Velocity.webp 1429w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure><div class=\"wp-block-media-text__content\"><p>Bernoulli\u2019s equation is based on <strong>conservation of energy<\/strong> along a streamline for an ideal fluid:<\/p>\n\n<p>P + \u00bd\u03c1v\u00b2 + \u03c1gh = constant.<\/p>\n\n<p>O\u00f9 ?<\/p>\n\n<ul class=\"wp-block-list\"><li>\u03c1gh = potential energy (elevation term)<\/li>\n\n<li>P = static pressure<\/li>\n\n<li>\u00bd\u03c1v\u00b2 = kinetic energy (velocity term)<\/li><\/ul><\/div><\/div><p>Bernoulli\u2019s equation does <strong>not say pressure creates flow<\/strong>. It says <strong>energy is redistributed<\/strong> between pressure, velocity, and elevation.<\/p><ul class=\"wp-block-list\"><li>When <strong>velocity increases<\/strong>, static pressure must <strong>decrease<\/strong><\/li>\n\n<li>When <strong>elevation increases<\/strong>, pressure must <strong>decrease<\/strong><\/li>\n\n<li>When velocity decreases, pressure can recover<\/li><\/ul><h3 class=\"wp-block-heading\" id=\"engineering-conclusion\"><strong>Engineering Conclusion<\/strong><\/h3><ul class=\"wp-block-list\"><li>Pressure and velocity are <strong>inversely related<\/strong>, not proportional<\/li>\n\n<li>High flow velocity often corresponds to <strong>low static pressure<\/strong><\/li>\n\n<li>Bernoulli explains phenomena such as:<ul class=\"wp-block-list\"><li>Pressure drop at pipe constrictions<\/li>\n\n<li>Venturi and orifice flow meters<\/li>\n\n<li>Cavitation risk at high velocity points<\/li><\/ul><\/li><\/ul><h3 class=\"wp-block-heading\" id=\"darcy-weisbach-equation-pressure-loss-due-to-friction\"><strong>Darcy\u2013Weisbach Equation \u2014 Pressure Loss Due to Friction<\/strong><\/h3><p>In real pipelines, <strong>friction dominates the pressure\u2013flow relationship<\/strong>.<\/p><p>This is described by the Darcy\u2013Weisbach equation:<\/p><p>\u0394P=f\u22c5D\/L\u22c5\u03c1v\u00b2\/2<\/p><p>O\u00f9 ?<\/p><ul class=\"wp-block-list\"><li>\u0394P = pressure drop<\/li>\n\n<li>f = friction factor (depends on Reynolds number and pipe roughness)<\/li>\n\n<li>L = pipe length<\/li>\n\n<li>D = pipe internal diameter<\/li>\n\n<li>v = average fluid velocity<\/li><\/ul><p>Pressure is consumed to <strong>overcome resistance<\/strong> caused by:<\/p><ul class=\"wp-block-list\"><li>Pipe wall friction<\/li>\n\n<li>Fluid viscosity<\/li>\n\n<li>Turbulence<\/li><\/ul><p>Unlike Bernoulli, this equation describes <strong>irreversible energy loss<\/strong>.<\/p><h3 class=\"wp-block-heading\" id=\"key-engineering-relationships\"><strong>Key Engineering Relationships<\/strong><\/h3><p>From Darcy\u2013Weisbach, several critical conclusions follow:<\/p><ol class=\"wp-block-list\"><li><strong>Pressure drop increases with velocity squared<\/strong>\u0394P\u221dv2 \u0394P\u221dv2\\Delta P \\propto v^2<\/li>\n\n<li><strong>Pressure drop increases linearly with pipe length<\/strong><ul class=\"wp-block-list\"><li>Doubling the length \u2248 doubling pressure loss<\/li><\/ul><\/li>\n\n<li><strong>Pressure drop increases dramatically as diameter decreases<\/strong><ul class=\"wp-block-list\"><li>Small diameter reduction \u2192 very large \u0394P increase<\/li><\/ul><\/li>\n\n<li><strong>Higher flow requires disproportionately higher pressure<\/strong><ul class=\"wp-block-list\"><li>Doubling flow may require <strong>3\u20134\u00d7 pressure increase<\/strong> (turbulent flow)<\/li><\/ul><\/li><\/ol><h3 class=\"wp-block-heading\" id=\"engineering-conclusion-1\"><strong>Engineering Conclusion<\/strong><\/h3><ul class=\"wp-block-list\"><li>Pressure does <strong>not control flow linearly<\/strong><\/li>\n\n<li>Flow is the result of pressure overcoming friction<\/li>\n\n<li>In long or small-diameter pipelines, pressure losses dominate system behavior<\/li>\n\n<li>This is why pump and compressor sizing is critical<\/li><\/ul><p>\ud83d\udc49 <strong>In most industrial pipelines, Darcy\u2013Weisbach is the governing relationship between flow and pressure.<\/strong><\/p><h3 class=\"wp-block-heading\" id=\"poiseuilles-law-flow-vs-pressure-in-laminar-viscous-flow\"><strong>Poiseuille\u2019s Law \u2014 Flow vs Pressure in Laminar, Viscous Flow<\/strong><\/h3><div class=\"wp-block-media-text is-stacked-on-mobile\"><figure class=\"wp-block-media-text__media\"><img decoding=\"async\" width=\"1024\" height=\"759\" src=\"http:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-1024x759.webp\" alt=\"Poiseuille\u2019s Law Flow vs Pressure in Laminar\" class=\"wp-image-27684 size-full\" srcset=\"https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-1024x759.webp 1024w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-300x222.webp 300w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-768x569.webp 768w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-340x252.webp 340w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-1536x1138.webp 1536w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-16x12.webp 16w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-1000x741.webp 1000w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar-1300x963.webp 1300w, https:\/\/metlaninst.com\/wp-content\/uploads\/2025\/12\/Poiseuilles-Law-Flow-vs-Pressure-in-Laminar.webp 2048w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure><div class=\"wp-block-media-text__content\"><p>Poiseuille\u2019s law applies to <strong>laminar flow<\/strong> (Reynolds number &lt; 2000), typically seen in:<\/p>\n\n<ul class=\"wp-block-list\"><li>Highly viscous fluids (oil, syrup, polymer melts)<\/li>\n\n<li>Low flow rates<\/li>\n\n<li>Small-diameter pipes or capillaries<\/li><\/ul>\n\n<p>The equation is:<\/p>\n\n<p>Q = \u03c0(P\u2081 \u2013 P\u2082)r\u2074 \/ 8\u03bcL.<\/p>\n\n<p>O\u00f9 ?<\/p>\n\n<ul class=\"wp-block-list\"><li>L is the length of the pipe.<\/li>\n\n<li>Q is the volumetric flow rate,<\/li>\n\n<li>P1 and P2 are the pressures at both ends of the pipe,<\/li>\n\n<li>r is the radius of the pipe,<\/li>\n\n<li>\u03bc is the viscosity of the fluid,<\/li><\/ul><\/div><\/div><p>In laminar flow:<\/p><ul class=\"wp-block-list\"><li>Fluid layers slide smoothly over each other<\/li>\n\n<li>Resistance comes primarily from <strong>viscous shear<\/strong><\/li>\n\n<li>Flow responds <strong>linearly<\/strong> to pressure<\/li><\/ul><h3 class=\"wp-block-heading\" id=\"key-engineering-insights\"><strong>Key Engineering Insights<\/strong><\/h3><ol class=\"wp-block-list\"><li><strong>Flow is directly proportional to pressure<\/strong><ul class=\"wp-block-list\"><li>Double pressure \u2192 double flow<\/li><\/ul><\/li>\n\n<li><strong>Flow is inversely proportional to viscosity<\/strong><ul class=\"wp-block-list\"><li>Higher viscosity \u2192 much lower flow<\/li><\/ul><\/li>\n\n<li><strong>Diameter has an extreme influence (D\u2074 relationship)<\/strong><ul class=\"wp-block-list\"><li>A small increase in diameter causes a massive increase in flow<\/li>\n\n<li>Reducing diameter slightly can almost stop flow<\/li><\/ul><\/li><\/ol><h3 class=\"wp-block-heading\" id=\"engineering-conclusion-2\"><strong>Engineering Conclusion<\/strong><\/h3><ul class=\"wp-block-list\"><li>Poiseuille\u2019s law explains why viscous fluids require:<ul class=\"wp-block-list\"><li>High pressure<\/li>\n\n<li>Large pipe diameters<\/li>\n\n<li><a href=\"https:\/\/metlaninst.com\/fr\/the-ultimate-guide-to-positive-displacement-flow-meter\/\">Positive displacement <\/a>or Coriolis flow meters<\/li><\/ul><\/li>\n\n<li>It is critical in:<ul class=\"wp-block-list\"><li>Oil and lubrication systems, espeically <a href=\"https:\/\/metlaninst.com\/fr\/les-5-premiers-debitmetres-dhuile-recommandes\/\">oil flow meter <\/a>selection.<\/li>\n\n<li>Chemical dosing<\/li>\n\n<li>Micro-flow and capillary systems<\/li><\/ul><\/li><\/ul><p>\ud83d\udc49 <strong>For viscous fluids, diameter matters more than pressure.<\/strong><\/p><h3 class=\"wp-block-heading\" id=\"how-pressure-really-relates-to-flow\"><strong>How Pressure Really Relates to Flow<\/strong><\/h3><p>From the three principles above, we can summarize:<\/p><ul class=\"wp-block-list\"><li><strong>Pressure does not \u201ccreate\u201d flow<\/strong><\/li>\n\n<li>Flow occurs when pressure <strong>overcomes resistance<\/strong><\/li>\n\n<li>The pressure\u2013flow relationship depends on:<ul class=\"wp-block-list\"><li>Flow regime (laminar vs turbulent)<\/li>\n\n<li>Viscosit\u00e9<\/li>\n\n<li>Pipe diameter and length<\/li><\/ul><\/li><\/ul><h3 class=\"wp-block-heading\" id=\"one-sentence-engineering-rule\"><strong>One-Sentence Engineering Rule<\/strong><\/h3><blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>Flow is not proportional to pressure \u2014 it is the result of pressure overcoming friction and viscosity.<\/p><\/blockquote><h2 class=\"wp-block-heading\" id=\"online-calculation-tool\"><strong>Online Calculation Tool<\/strong><\/h2><p>This&nbsp;<strong>pipe flow rate calculator<\/strong>&nbsp;calculates the volumetric flow rate (<strong>discharge rate<\/strong>) a gas or fluid (liquid) going through a round or rectangular pipe of known dimensions. If the substance is a liquid and its volumetric density is known the calculator will also output the mass flow rate (more information is required to calculate it for gases and it is currently not supported).<\/p><p>In&nbsp;<strong>pressure difference<\/strong>&nbsp;mode the calculator requires the input of the pressure before the pipe (or venturi, nozzle, or orifice) as well as at its end, as well as its cross-section, e.g. pressure and diameter for a round pipe. Supported input units include pascals (Pa), bars, atmospheres, pounds per square inch (psi), and more for pressure and kg\/m\u00b7s, N\u00b7s\/m2, Pa\u00b7s, and cP (centipoise) for dynamic viscosity.<\/p><p>In&nbsp;<strong>flow velocity<\/strong>&nbsp;mode one needs to know the flow velocity of the gas or fluid (feet per second, meters per second, km\/h, etc. are accepted) in order to calculate the flow rate.<\/p><div class=\"gigacalculator\" data-tool=\"\/calculators\/pipe-flow-rate-calculator.php\" data-width=\"750\">\n  <div class=\"gigacalctitle\">Flow Rate Calculator<\/div>\n  <div class=\"gigacalcfooter\">\n    <a href=\"https:\/\/www.gigacalculator.com\/calculators\/pipe-flow-rate-calculator.php\" target=\"_blank\" rel=\"noopener\">Flow Rate Calculator<\/a> by <a class=\"gigacalclink\" href=\"https:\/\/www.gigacalculator.com\/\" target=\"_blank\" rel=\"noopener\">GIGAcalculator.com<\/a>\n  <\/div>\n<\/div>\n<script defer src=\"https:\/\/cdn.gigacalculator.com\/embed.min.js\"><\/script>","protected":false},"excerpt":{"rendered":"<p>In fluid systems, few topics are as fundamental\u2014and as frequently misunderstood\u2014as the relationship between flow and pressure in a pipe. Engineers often hear statements like \u201chigher pressure means higher flow\u201d or \u201clow pressure causes low flow\u201d, yet in real pipeline systems, the relationship is far more nuanced. Accurate understanding of pipe flow vs pressure is [&hellip;]<\/p>","protected":false},"author":1,"featured_media":27685,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[123],"tags":[],"class_list":["post-27682","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-flow-meters"],"_links":{"self":[{"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/posts\/27682","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/comments?post=27682"}],"version-history":[{"count":3,"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/posts\/27682\/revisions"}],"predecessor-version":[{"id":27714,"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/posts\/27682\/revisions\/27714"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/media\/27685"}],"wp:attachment":[{"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/media?parent=27682"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/categories?post=27682"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/metlaninst.com\/fr\/wp-json\/wp\/v2\/tags?post=27682"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}