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To calculate the expected C v for a valve controlling water or other liquids that behave like water, the basic liquid sizing equation above can be re-written as follows C V = Q G ∆P (2) Viscosity Corrections Viscous conditions can result in significant sizing errors in using the basic liquid sizing equation, since published C v values are
16 Φεβ 2023 · A valve’s flow coefficient (Cv) measures the flow of water through the valve at 60 °F in U.S. gallons per minute (GPM). Pipefitters, engineers, and manufacturers use Cv to determine the appropriate size of valves for the specific volume of fluid that flows through them.
25 Νοε 2010 · How to add flow coefficients for control valves in series or parallel. Comparing flow coefficients Cv to flow factors Kv. Critical pressure ratios for water and other liquids. Designing steam control valves and their Kv values. Steam pipes and pressure drop diagrams - imperial and metric units.
25 Νοε 2010 · Comparing flow coefficients Cv to flow factors Kv. The flow coefficient - Cv - or the flow factor - Kv - are commonly used to specify capacities of control valves. Control Valve terminology, bodies, trim, flow characteristics, Cv and Kv sizing, noise, actuators, positioners and more.
Hence, one Cv equals the flow of one U.S. gallon per minute of water at 60°F and under a pressure drop across the valve of 1 psi. Now the same valve will flow 10 gpm at a pressure drop of 100 psi since the flow is proportional to the square root of ΔP, thus following the laws of fluid mechanics.
In more practical terms, the flow coefficient C v is the volume (in US gallons) of water at 60 °F (16 °C) that will flow per minute through a valve with a pressure drop of 1 psi (6.9 kPa) across the valve.
Cv = flow coefficient defined as gpm of 60F water with 1 psi pressure drop d = diameter of pipe or valve, in D = diameter of pipe or valve, ft
