About ValveTool

Most valve and piping questions come down to a handful of small numbers. What flow coefficient does this duty actually need? How much pressure will the valve consume at design flow? Is the fluid moving fast enough in the pipe to erode it, or slow enough to sit in the laminar range? Each one is a short calculation, but grinding through all of them by hand — and converting between gpm, litres per minute, and cubic metres per hour along the way — is where a straightforward sizing job turns into error-prone busywork.

ValveTool exists to take that arithmetic off your desk. Instead of long articles you have to read end to end, the site is built around a set of small, single-purpose calculators, each aimed at one part of a fluid system. The Valve Cv Calculator turns a flow rate, pressure drop, and specific gravity into the required flow coefficient, in both US Cv and metric Kv. The Valve Pressure Drop Calculator runs that relationship the other way — flow and valve Cv into the pressure the valve imposes, in psi and bar. The Flow Velocity Calculator takes a volumetric flow and the pipe inside diameter and reports the fluid velocity, flagging lines that run faster than common design limits. The Valve Sizing Calculator computes the Cv a duty demands and recommends the next-larger rated Cv so the valve keeps travel in reserve. The Flow Rate Unit Convertermoves a flow figure between GPM, L/min, m³/h, and CFM. And the Reynolds Number Calculator classifies the flow as laminar, transitional, or turbulent from velocity, diameter, and viscosity.

The numbers behind those tools are standard fluid mechanics: the liquid Cv equation, Cv = Q × √(SG/ΔP), and its rearrangements; the continuity relation v = Q/A with A = (π/4)d²; the Kv ≈ 0.865 × Cv factor between US and metric flow coefficients; and Re = v·d/ν with the familiar 2300 and 4000 regime thresholds. Beyond the calculators, the blog and learnsection cover valve types and selection, sizing, actuation, cavitation, and piping fundamentals — the reasoning behind the figures the tools produce. The museum is a separate, browsable collection drawn entirely from Wikipedia and Wikimedia Commons; it is there for the pleasure of looking, not as an engineering reference.

A few things worth stating plainly. ValveTool is an independent site, not a valve manufacturer, supplier, or distributor, and not affiliated with any valve brand or standards body. It is supported by advertising, which is how the tools stay free with no account required. Every result — a Cv, a pressure drop, a velocity, a recommended valve size, a Reynolds number — is a general estimate for preliminary sizing, built on standard formulas and the numbers you enter, and it assumes clean, non-choked liquid flow. Real service depends on the exact valve, the fluid and its temperature, cavitation and flashing, gas or two-phase behaviour, and the loads and environment the system sees. These are engineering estimates, not professional engineering advice — verify with the valve manufacturer’s data and a qualified engineer before finalizing anything. If a tool looks wrong, or there’s a calculator you wish existed, the contact page is the place to say so.