Fluid Power Formulas

Cylinder Speed and Motor Torque

Fluid Pressure

Pounds/Square Inch

Pressure=Force (pounds) /Unit Area (Square Inches) P=F/A or psi=F/A

Cylinder Area

Square Inches

Area= p x Radius2 inches

A=pr2

Area=(p/4)x Diameter2 inches

A=pD2/4 or A=0.785D2

Cylinder Force

Pounds

Force= Pressure (psi) x Net Area (square inches)

F=psi x A or F=PA

Cylinder Speed

Feet/second

Velocity= (231 x Flow rate (gpm))/(12x60xNet Area (square inches))

V=231Q/720A or V=0.3208Q/A

Cylinder Volume Capacity

Gallons

Volume=(pxRadius2(inches)x Stroke (inches) )/231

V=pr2L/231

Volume=Net Area (square inches) x Stroke (inches)/231

V=AL/231 L=stroke length

Cylinder Flow Rate

Gallons per minute

Flow Rate=(12x60xVelocity(feet/sec) xNet Area(square inches))/231

Q=720vA/231 or Q=3.117vA

Fluid Motor Torque

Inch pounds

Torque=(Pressure(psi)xF.M.Displacement(cubic inch/rev))2p

T=psi d/2p or T=Pd/2p

Torque=(Horsepowerx63025/RPM

T=63025 HP/n

Torque=Flow Rate(gpm)xPressure(psi)x36.77/RPM

T=36.77QP/n or T=36.77psi/n

Fluid Motor Torque/100psi

Inch pounds

Torque/100psi=F.M. Displacement (cubic inches/rev)/.0628

T100psi=d/.0628

Fluid Motor Speed

Revolutions/Minute

Speed=231 x Flow rate (gpm)/F.M. Displacement (cubic inches /revolution)

n=231Q/d

Fluid Motor Power

Horsepower Output

Horsepower=Torque Output (inch pounds) x RPM/63025

HP=Tn/63025

Pump Outlet Flow

Gallons per Minute

Flow= RPM x Pump Displacement (cubic inches/revolution)/231

Q=nd/231

Pump Input Power

Horsepower required

Horsepower input=Flow Rate Output (gpm) x Pressure (psi)/1714 x Efficiency (Overall)

Hpin=QP/1714Eff or Hpin=GPM x psi/1714Eff

Flow Rate Through Pipe

Feet/Second

Velocity=0.3208 x Flow rate Through I.D. (gpm)/Internal Area (square inches)

V=0.3208/A

Compressibility of Oil

Additional Oil required to reach Pressure

Additional Volume=Pressure(psi)xVolumeof Oil Under Pressure/250,000

VA=PV/250,000

Approximately ½% per 1000 psi

Fluid Power Formulas, Fluid Pressue, Cylinder Area, Cylinder Force, Cylinder Speed,
Cylinder Volume, Flow Rate, Fluid Motor Torque, Fluid Motor Speed, Fluid Motor Power,
Fluid Motor Outlet Flow, Pump Input Power, Flow Rate Through Pipes, Compressibility of
Oil, Hydraulic Motors, Hydraulic Cylinders, Hydraulic Pumps, Pneumatic Cylinders,
Pneumatic Motors

Numberfactory: Fluid Power Formulas