Flow and Pressure

Valve Flow Coefficient (Cv)

Cv is the flow (in GPM) of water through the valve with a 1psi pressure drop. Knowing Cv and either the desired flow rate or pressure drop allows you to calculate the other parameter (ie pressure drop at a given flow rate or flow rate at a given pressure drop). Use the specific gravity (density relative to water) for liquids other than water.

Actual Cubic Feet (ACF) to Standard Cubic Feet (SCF)

Convert the volumetric flow rate of a gas at operating conditions (ACM) to the flow rate at standard conditions (SCFM). Manufacturers typically rate their equipment at standard conditions, and this allows you to account for variations in actual service conditions.

Water Hammer

Water hammer is a pressure spike cause by the sudden stoppage of fluid flow. Calculate the pressure spike given the input parameters (yellow highlighted cells). This empirical formula is for water only.


Cavitation occurs when the there is a large pressure drop across the valve and the downstream pressure is slightly above the liquid vapor pressure. Eddy pockets of low pressure cause the liquid to flash and recondense. Recondensing micro-implosions result in significant pressure spikes which can quickly erode and damage the valve.

Conversion Calculators


Input a value in one cell (yellow highlight) to see conversion to other units in the corresponding row.