For measuring the valve capacity of control valves the coefficient cv or its metric equivalent kv is adopted. The valve coefficient cv in imperial unit the number of us gallon per minute of water at 60 f that will flow through a valve at specific.
Gallons that can pass through a valve in a fully open position at a pressure drop of 1 psi.
Cv factor for valves. In a situation of special travel and differential pressure 1 lbf in2. This depends on how the valve has been designed to let the flow going through the valve. What is flow coefficient cv.
Each valve has its own flow coefficient. The flow coefficient c v is based on the imperial units system and is defined as. The valve flow coefficient cv is the number of u s.
The valve flow coefficient cv is the number of u s. And if cv factor is same flow rate is big so that differential pressure is big. Flow factor k v.
In more practical terms the flow coefficient c v is the volume in us gallons of water at 60 f that will flow per minute through a valve with a pressure drop of 1 psi across the valve. Cv factor is using generally it is expressed factor for fluid 60 f that flow into valve by us gal min. The valve flow coefficient c v is a convenient way to represent flow capacity of a valve across a range of fluids and process parameters.
The valve flow coefficient cv or its metric equivalent kv has been adopted universally as a comparative value for measuring the capacity of control valves. The flow coefficient for a control valve which in full open position passes 25 gallons per minute of water with a one pound per square inch pressure drop can be calculated as. Cv 25 gpm 1 1 psi 1 2.
The c v calculator will calculate either c v or flow using the supplied additional parameters of fluid inlet and outlet pressure and fluid temperature. The cv tells you how to properly size your valve so it has minimal effect on the hydraulic efficiency you ve engineered into your system. Therefore the main differences between different flow coefficients come from the type of valve and of course the opening position of the valve.
It is a number published by the valve manufacturer that describes the number of u s. Go to online calculation of the flow coefficient cv and kv. If differential pressure is same flow rate is big so that cv factor is big.
A valve with a high cv passes fluid more easily than one with a low cv. Gallons per minute of water at 60 f that will flow through a control valve at a specified opening when a pressure differential of 1psi is applied across the valve. The flow of water through a valve at 60 o f in us gallon minute at a pressure drop of 1 lb in 2.
How do we get value 1 156 conversion factor in formula cv 1 156kv or cv 1 156 q sqrt g delta p. The flow coefficient is commonly used in the u s. The cv factor is a standard used by all valve manufacturers.
Water control valves flow coefficient c v diagram. Gallons per minute of water at 60 f that will flow through a control valve at a specified opening when a pressure differential of 1psi. The use of the flow coefficient offers a standard method of comparing valve capacities and sizing valves for specific applications that is widely accepted by industry.