Useful Formulas

Compressor RPM =

motor pulley p.d. X motor RPM

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compressor pulley p.d.
Motor Pulley p.d. =

compressor pulley p.d. X compressor RPM

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motor pulley p.d.
Compressor Pulley =

motor pulley p.d. X motor RPM

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compressor RPM
Motor RPM =

compressor pulley p.d. X compressor RPM

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motor pulley p.d.
Piston Displacement in CFM =

cylinder bore X cylinder bore X stroke in inches

X RPM

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2200
Cubic Feet Compressed Air =

cu. ft. free air X atmospheric pressure

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(PSIG + 14.7)
Cubic Feet Free Air =

cu. ft. compressed air X (PSIG 14.7)

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Atmospheric pressure
Piston speed in feet per minute =

2 X stroke (in inches) X RPM

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12
Gallons = cu. ft. X 7.46
Cubic Feet = gallons X .134
PSI = bar X 14.5
BAR = psi X 0.069
Cubic Feet = cu. meter X 35.31
Cubic Meter = cu. ft. X 0.028