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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.


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David Sirjue June 7, 2018 at 9:13 pm

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.

azetou July 16, 2019 at 7:01 pm

was gonna write this and then I saw your comment

jagadish bhushi December 4, 2019 at 6:36 am

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

Aquatech Systems January 28, 2020 at 5:50 pm

Anyone please suggest how to calculate compressor capacity for pneumatic valves.

Karik April 24, 2020 at 1:36 pm

This is incorrect calculation. The air will be consumed during the opening process, not closing which is venting to ATM. Also the volume is not converted into standard condition.


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Air Consumption Calculation for ON/OFF Valves

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