B B Hydraulics logo

SHOP NOW

BASIC FLUID POWER FORMULAS
HYDRAULICS / PNEUMATICS

VARIABLE

Fluid Pressure - P

Fluid Flow Rate - Q

Fluid Power in Horsepower - HP

WORD FORMULA WITH UNITS

(PSI) = Force (Pounds) / Area ( Sq. In.)

GPM= Flow (Gallons) / Unit Time (Minutes)

Horsepower = Pressure (PSIG) × Flow (GPM)/ 1714

SIMPLIFIED FORMULA

P  =  F / A

Q  =  V / T

HP  =  PQ / 1714

ACTUATOR FORMULAS

VARIABLE

Cylinder Area - A

Cylinder Force - F

Cylinder Speed - v

Cylinder Volume Capacity - V

Cylinder Flow Rate - Q

Fluid Motor Torque - T

Fluid Motor Speed - n

Fluid Motor Horsepower - HP

WORD FORMULA WITH UNITS

( Sq. In.) = π × Radius (inch)2

(Sq. In.) = π × Diameter (inch)2 / 4

(Pounds) = Pressure (psi)   × Area (sq. in.)

(Feet / sec.) = (231 × Flow Rate (gpm)) / (12 × 60 × Area)

Volume = π × Radius2 × Stroke (In.) / 231

Volume = 12 × 60 × Velocity (Ft./Sec.) × Net Area(In.)2 / 231

Torque (in. lbs.) = Pressure (psi) × disp. (in.3 / rev.) / 6.2822

Torque = HP × 63025 / RPM

Torque = Flow Rate (GPM) × Pressure × 36.77 / RPM

Speed (RPM)  =  (231 × GPM) / Disp. (in.)3

HP = Torque (in. lbs.) × rpm / 63025

SIMPLIFIED FORMULA

A  =  π  × R2

A  = π  × D2 / 4

F  =  P × A

v   =  (0.3208 × gpm) / A

V = π × R2 × L / 231

(L = length of stroke)

Q = 3.11688 × v × A

T  =  P × d / 6.2822

T = HP × 63025 / n

T = 36.77 × Q × P / n

n  =  (231 × GPM) / d

HP  =  T × n / 63025

PUMP FORMULAS

VARIABLE

Pump Output Flow - GPM

Pump Input Horsepower - HP

Pump Efficiency - E

Pump Volumetric Efficiency - E

Pump Mechanical Efficiency - E

Pump Displacement - CIPR

Pump Torque - T

WORD FORMULA WITH UNITS

GPM = (Speed (rpm) × disp. (cu. in.)) / 231

HP =  GPM × Pressure (psi) / 1714 × Efficiency

Overall Efficiency = Output HP / Input HP

Overall Efficiency = Volumetric Eff. × Mechanical Eff.

Volumetric Efficiency = Actual Flow Rate Output (GPM) / Theoretical Flow Rate Output (GPM) × 100

Mechanical Efficiency = Theoretical Torque to Drive / Actual Torque to Drive × 100

Displacement (In.3 / rev.) = Flow Rate (GPM) × 231 / Pump RPM

Torque = Horsepower × 63025 / RPM

Torque = Pressure (PSIG) × Pump Displacement (CIPR) / 2π

SIMPLIFIED FORMULA

GPM =  (n ×d) / 231

HP  =  (Q ×P) / 1714 × E

EOverall = HPOut / HPIn X 100

EOverall = EffVol. × EffMech.

EffVol. = QAct. / QTheo. X 100

EffMech = TTheo. / TAct. × 100

CIPR = GPM × 231 / RPM

T = 63025 × HP / RPM

T = P × CIPR / 6.28

Quality service & competitive prices since 1989.

B & B Hydraulics

2400 Line Rd.

Hutchinson, KS  67501