The flow coefficient of a device is a relative measure of its efficiency at allowing fluid flow. Material compatibility and product ratings.
Proper installation operation and maintenance are also required to assure safe trouble.
Pneumatic valve cv rating. In deciding the size of the control valve that port size we need to calculate the cv value of the process calculated cv by calculating cv has educated more than 50 years which is involved in. For a quick guide to valve designs see table 3. A valve that is sized correctly is a valve that is quiet has accurate flow control lasts beyond its expected life span and does not leak.
This is the basic equation for cv where q is the rate of flow gallons per minute sg is the specific gravity of the fluid and p is the pressure drop across the valve psi. Cv with 2 psi pressure drop cv with 5 psi pressure drop cv with 10 psi pressure drop search tools. Scfm air flow through a valve orifice having a cv factor of 1 00.
Such as the renault number reynolds number flow rate flow the shock choking the involved joints in pipes fitting and the other by the values of these. 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. Choosing the valve series your next step is to choose a basic valve design to do the job.
The cv rating for each valve is listed in the tables found in the valve catalog. A pneumatic valve is the equivalent of an electrical switch which in this case either allows or prevents air from passing finally we can calculate the needs of other machines to determine a facility s required compressor capacity the pneumatic equivalent of an electric generator. The cv or flow coefficient of the valve plays a much larger part in the valve s performance than determining how many gpm gallons per minute can pass through the valve.
Part number search. Q is the rate of flow expressed in us gallons per minute. Example flow coefficient liquid.
Flow rate given the cv and δp cv given the flow rate and δp. The definition of cv is the of gallons of water that will flow through the valve with a 1 psi pressure differential when the valve is open. Air valve sizing calculator.
Cv 1 x 28 8 1 06 any valve therefore which has a cv of at least 1 06 will extend our cylinder the specified distance in the required time. It is commonly understood that nearly every pneumatic device creates a flow restriction in the system. C v 25 gpm 1 1 psi 1 2 25 flow coefficient c v for saturated steam since steam and gases are compressible fluids the formula must be altered to accommodate changes in.
The equations below can be used to determine. On valves or orifices with other cv factors the flow capacity will be directly proportional to the cv rating. Having selected the basic valve design consult the.
Mathematically the flow coefficient c v or flow capacity rating of valve can be expressed as. For example a valve with cv of 4 00 will pass 4 times as much flow at the same pressure difference as shown in the chart. It describes the relationship between the pressure drop across an orifice valve or other assembly and the corresponding flow rate.