Q is the rate of flow expressed in us gallons per minute. The flow coefficient of a device is a relative measure of its efficiency at allowing fluid flow.
Valve Selection For Bypass Of Control Valves A Case Study
Cv value check valve. Basically the larger the opening in a valve the larger the cv. Cv value swing check valve 14 14 24 81 140 250 280 510 750 1100 1900. It can be assumed that the tests are done with water unless otherwise noted using a specific gravity of 10 12 centistoke viscosity and a standard temperature of 60 degrees fahrenheit. Mathematically the flow coefficient c v or flow capacity rating of valve can be expressed as. Flow capacity in imperial units gpm us gallons per minute that a valve will pass for a pressure drop of 1 lbin 2 psi the flow factor kv is also commonly used with capacity in si units. It describes the relationship between the pressure drop across an orifice valve or other assembly and the corresponding flow rate.
Flow coefficients for 600 class bolted bonnet api 600 type valves valve size gate globe stop check swing check tilting disc check and lift check full port cv t pattern cv y pattern cv full port cv min. The process of valve size selection the same formula is used determine the valve cv necessary for a required flow rate and desired pressure drop. Valve flow coefficient cv is a valves capacity for a liquid or gas to flow through it. As a valve is opened more and more the cv increases until the valve is fully open where it reaches its highest possible cv or 100 open cv. With the flow coefficients capacities of valves at different sizes types and manufacturers can be compared. Check valve cv 18 2 npt mawp up to 4500 psig.
High flow zero leak low pressure drop check valve suitable for many fluid and gas applications. The valves flow coefficient cv is a value that is determined by flow testing for each valve size. The flow coefficients are in general determined experimentally and express the. Valves with a reduced port have an internal seat diameter that is smaller than the nominal pipe size. C v calculator for valve sizing. Butterfly valve cv values vary with the disc angle and valve size.
Fully guided poppet with free floating o ring design is extremely tolerant of particulate contamination. The valve flow coefficient c v is a convenient way to represent flow capacity of a valve across a range of fluids and process parametersthe c v calculator will calculate either c v or flow using the supplied additional parameters of fluid inlet and outlet. Flow velocity regular port cv flow velocity for fully open 1 for fully open1 ftsec water 60ºf ftsec water 60ºf 1 12 141 25 47 83. Valves are tested by running water through it before publishing the cv value. This calculator can be used to help select a valve with enough flow capacity for a given application. Full port valves will have a higher cv than reduced port valves.
In the chart below we show the approximate cv value of butterfly valves ranging from 2 to 24 and at various disc angles.
Gallery of Cv Value Check Valve
