Literally Cv means coefficient of velocity. Cv is generally used to compare flows of valves. The higher the Cv, the greater the flow.
It is sometimes helpful to convert Cv into SCFM(Standard Cubic Feet per Minute) and conversely, SCFM into Cv. Although Cv represents flow capacity at all pressures, SCFM represents flow at a specific air pressure. Therefore, the following chart relates Cv to SCFM at a group of pressures.
To obtain SCFM output at a particular pressure, divide the valve Cv by the appropriate factor shown below.
| Cv to SCFM Conversion Factor Table |
| PSI of Air Pressure |
40 |
50 |
60 |
70 |
80 |
90 |
100 |
| Factor |
0.0370 |
0.0312 |
0.0270 |
0.0238 |
0.0212 |
0.0192 |
0.0177 |
Example: What is the output inSCFM of a value with a Cv of 0.48 when operated
at 100 PSI?
0.48(Cv)/0.0177(Factor) = 27SCFM
To convert SCFM into Cv, simply reverse the process and multiply the SCFM times
factor. |