We have compiled a list of liquid flow and air flow formulae to allow users to calculate solenoid valve flow and pressure drop which are the key factors when choosing any solenoid, angle seat or process valve. This helps make sure systems will have sufficient flow, the correct valve size so avoiding additional costs or valve failure.
A complete media viscosity cross reference guide as liquid media thickness can be measured in various formats so in this way engineers will avoid installing a solenoid or process valve that would not be compatible with the media being controlled.
Q=Kv x Square Root of (DP/d) or DP=d(Q/Kv)2
Where DP less than P1/2 : Q=1.69Kv x Sq Rt (DPxP2)
Where DP equal to P1/2 : Q = 0.84Kv x P1
| Saybolt Universal (seconds) | Engler (degrees) | Kinematic (centistokes) | Saybolt Universal (seconds) | Engler (degrees) | Kinematic (centistokes) |
|---|---|---|---|---|---|
| - | 1.05* | 1.5 | 103 | 3.0 | 21.3 |
| 34 | 1.15* | 2.5 | 109 | 3.2 | 22.8 |
| 37 | 1.25* | 3.4 | 115 | 3.4 | 24.1 |
| 40 | 1.3* | 4.2 | 125 | 3.7 | 26.7 |
| 42 | 1.4* | 5.0 | 137 | 4.0 | 29.2 |
| 45 | 1.45* | 5.7 | 148 | 4.3 | 31.7 |
| 50 | 1.6* | 7.5 | 160 | 4.6 | 34.2 |
| 57 | 1.8* | 9.4 | 171 | 4.9 | 36.8 |
| 62 | 1.9 | 11.0 | 183 | 5.2 | 39 |
| 68 | 2.1 | 12.6 | 205 | 5.9 | 44 |
| 74 | 2.2 | 14.2 | 242 | 7 | 50 |
| 79 | 2.4 | 15.5 | 256 | 7.3 | 55 |
| 85 | 2.6 | 17.0 | 285 | 8.1 | 62 |
| 92 | 2.7 | 18.6 | 313 | 8.9 | 68 |
| 98 | 2.9 | 20.0 | 342 | 9.8 | 74 |
From °F to C° : Add 40 then multiply by 5 then divide by 9 then -40
From C° to F° : Multiply by 9 then –40 divide by 5 then +40
Kv value is the metric measure for the flow of a valve. It is defined as: The volume flow in cubic metres per hour of water at a temperature of between 5° and 40° Celsius with a pressure drop across the valve of 1 bar.
Cv is the imperial measure for the flow of a valve. It is defined as: The volume flow in US gallons per minute of water at a temperature of 60° Fahrenheit with a pressure drop across the valve of 1 psi.
Qn value is used in pneumatics to define the flow of a valve. It is defined as: The volume flow in litres per minute of air at a temperature of 20° Celsius, with an input pressure of 6 bar and a pressure drop across the valve of 1 bar.