# Air Consumption Calculation for ON/OFF Valves

#### Air Consumption Calculation for ON/OFF Valves

Generally we specify air consumption in SCFM ( standard cubic feet per minute) for on/off valve as an intermediate (Non-continuous) service.

Air Consumption calculation for ON/OFF valves are given in liters by many European actuator vendors and Process Engineer demands consumption in SCFM. (I faced this in one project here)

Now let us learn how we can calculate the consumption in SCFM from Liters .

Actuator Manufactures select actuator based on Valve details and Torque Valves and selected actuator Displacement volume is in Liters (capacity)

1) ESDV -100 with 18″ full bore 900 RTJ size , Selected actuator is having 160.15 Liter (Displacement volume)

2) Convert the actuator displacement volume, Liter in SCF (standard cubic feet)

1L = 0.035315ft³

160.15 Liter – 5.65 ft³

3) Now ESDV is fail close valve and air consumption is more during opening of the valve ( actuator volume gets filled) and valve closing time for ESDV-100 is say 54 Sec (3 Sec per inch)

Actuator volume 5.65 cubic feet has to be filled in 54 sec (Air consumption)

Per second air consumption is 5.65 / 54 = 0.1046 Cubic Feet per second

Now convert this in Minutes

0.1046 CFS = 6.276 Cubic Feet Minute.

It shall be noted that air consumption always depends on air supply pressure and need to be specified as SCFM @ air supply pressure.

Credits : VINAYAK DUMBRE

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### 5 thoughts on “Air Consumption Calculation for ON/OFF Valves”

1. The last sentence need to be checked for accuracy. SCFM references volume at standard conditions of temperature and atmospheric pressure so ‘SCFM @ air supply pressure’ is contradictory.

2. was gonna write this and then I saw your comment

3. What is normal pnematic On/off valve sizes say100 nb,150nb,200nb