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Fluid Power Formulas
You have a job to do and remembering every formula can be tough. Use these formulas to make your day a little easier.
Basic Fluid Power Formulas
Variable
Word Formulas with Units
Simplified Formulas
Fluid Pressure – P
(PSI) = Force (Pounds) / Area (Sq. In.)
P = F / A
Fluid Flow Rate – Q
GPM = Flow (Gallons) / Unit Time (Minutes)
Q = V / T
Fluid Power in Horsepower – HP
Horsepower = Pressure (PSIG) × Flow (GPM)/ 1714
HP = PQ / 1714
Pump Formulas
Variable
Word Formulas with Units
Simplified Formulas
Pump Output Flow – GPM
GPM = (Speed (rpm) × disp. (cu. in.)) / 231
GPM = (n ×d) / 231
Pump Input Horsepower – HP
HP = GPM × Pressure (psi) / 1714 × Efficiency
HP = (Q ×P) / 1714 × E
Pump Efficiency – E
Overall Efficiency = Output HP / Input HP
EOverall = HPOut / HPIn X 100
Pump Efficiency – E
Overall Efficiency = Volumetric Eff. × Mechanical Eff.
EOverall = EffVol × EffMech.
Pump Volumetric Efficiency – E
Volumetric Efficiency = Actual Flow Rate Output (GPM) / Theoretical Flow Rate Output (GPM) × 100
EffVol = QAct. / QTheo.X 100
Pump Mechanical Efficiency – E
Mechanical Efficiency = Theoretical Torque to Drive / Actual Torque to Drive × 100
EffMech= TTheo / TAct. × 100
Pump Displacement – CIPR
Displacement (In.3 / rev.) = Flow Rate (GPM) × 231 / Pump RPM
CIPR = GPM × 231 / RPM
Pump Torque – T
Torque = Horsepower × 63025 / RPM
T = 63025 × HP / RPM
Pump Torque – T
Torque = Pressure (PSIG) × Pump Displacement (CIPR) / 2π
T = P × CIPR / 6.28
Actuator Formulas
Variable
Word Formulas with Units
Simplified Formulas
Cylinder Area – A
(Sq. In.) = π × Radius (inch)2
A = π × R2
Cylinder Area – A
(Sq. In.) = π × Diameter (inch)2/ 4
A = π × D2 / 4
Cylinder Force – F
(Pounds) = Pressure (psi) × Area (sq. in.)
F = P × A
Cylinder Speed – v
(Feet / sec.) = (231 × Flow Rate (GPM)) / (12 × 60 × Area)
V = (0.3208 × GPM) / A
Cylinder Volume Capacity – V
Volume = π × Radius2 × Stroke (In.) / 231
V = π × R2 × L / 231
Cylinder Flow Rate – Q
Volume = 12 × 60 × Velocity (Ft./Sec.) × Net Area (In.)2 / 231
Q = 3.11688 × v × A
Fluid Motor Torque – T
Torque (in. lbs.) = Pressure (psi) × disp. (in.3 / rev.) / 6.2822
T = P × d / 6.2822
Fluid Motor Torque – T
Torque = HP × 63025 / RPM
T = HP × 63025 / n
Fluid Motor Torque – T
Torque = Flow Rate (GPM) × Pressure × 36.77 / RPM
T = 36.77 × Q × P / n
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