When sizing calculating which size valve is needed for your application a control valve specialist needs to calculate the flow coefficient. 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 opening with a pressure drop of 1 psi across the valve.
Calculating control valve cv.
Valve cv calculation metric. Flow coefficient cv and flow factor kv are values used to specify the hydraulic capacity of a control valve. Kv is the flow coefficient in metric units. Same model valve has different coefficient for each diameter.
The relationship between cv and kv is. With a temperature range 5 to 30 c and pressure drop of 1 bar. 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.
Types of control valves noise. 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 c v calculator will calculate either c v or flow using the supplied additional parameters of fluid inlet and outlet. Valve technician interview questions.
It is defined as the flow rate in us gallons per minute gpm of water at a temperature of 60º fahrenheit with a pressure drop across the valve of 1 psi. In metric units the same valve above with a specified opening giving cv 1 will pass 0 862m3 hr of water at 15 degree celsius if 1bar pressure difference δp exist between upstream and downstream points on each side of the valve. Kv 0 864 cv.
Cv 48000 248 33 03 x sqrt 0 86 x 273 240. The flow factor kv in metric unit the amount of water that will flow in m3 hr. It is defined as the flow rate in cubic meters per hour m3 h of water at a temperature of 16º celsius with a pressure drop across the valve of 1 bar.
The flow of water in metres cubed per hour m hr at a pressure drop of bar. Control valve tips and tricks. The flow rate for a liquid q cv sq.
Flow factor is the metric equivalent of flow coefficient and is defined as. Flow coefficient is an imperial measurement and is defined as. What is butterfly check valve.
C v calculator for valve sizing. The flow of water through a valve at 60 f in us gallons minute gpm at a pressure drop of 1lb in. Control valve cv refers to the flow coefficient of the valve.
It applies to the factor of the head drop δh or pressure drop δp over a valve with the flow rate q. Cv is the flow coefficient in imperial units. They express coefficient cv kv as the flow rate of water in g p m.
This calculator can be used to help select a valve with enough flow capacity for a given application. You can use the calculator to calculate maximum flow rate through control valve for given pressure drop and known flow coefficient of control valve cv. Articles you may like.
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Root of δp sg q. Cv 25 gpm 1 1 psi 1 2. Example flow coefficient liquid.