horsepower formulas

7/18/2019 Horsepower Formulas

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HORSEPOWER FORMULAS

For Rotating Objects

HP =

Where T = Torque (lbft)N = Speed (rpm)

Objects in LinearMotion

HP =

WhereF = Force (lbs)V = Velocity (ft/min)

For Pumps HP =

HP =

Where

GPM = Gallons per MinuteHead = Height of Water (ft)Efficiency of Pump = %/100

PSI = Pounds per Inch

Specific Gravity of Water = 1.01 CuFt per Sec. = 448 GPM1 PSI = A Head of 2.309 ft (water weight)62.36 lbs per CuFt at 62°F

For Fans andBlowers

HP =

HP =

HP =

Where

CFM = Cubic Feet per MinutePSF = Pounds per Square FootPIW = Inches of Water GaugePSI = Pounds per Square InchEfficiency of Fan = %/100



For Conveyors HP (verticle)

HP

(horizontal)

Where

F = Force (lbs)V = Velocity (ft/min)

Coef. of Friction• Ball or Roller Slide = 0.02 • Dovetail Slide = 0.20 • Hydrostatic Ways = 0.01 • Rectangle Ways with Gib = 0.01 to 0.25

TORQUE FORMULAS

T = HP x 5252

N

WhereT = Torque (LbFt)HP = HorsepowerN = Speed (rpm)

T = F x R

WhereT = Torque (LbFt)F = Force (Lbs)R = Radius (Ft)

Ta(accelerating)

WK2 x Change in RPM

308 x t (Sec)

Where

Ta = Torque (LbFt)WK2 = Inertia at Motor Shaft (LbFt)2t = Time to Accelerate (Sec)

Note:

To change LbFt2 to InLbSec2, Divide by 2.68To change InLbSec2 to LbFt2, Mult. by 2.68

AC MOTOR FORMULAS

Sync Speed = Freq x 120

Number of Poles

WhereSync Speed = Synchronous Speed (Rpm)

Freq = Frequency (Hz)



% Slip = (Sync Speed - FL Speed) x 100

Sync Speed

WhereFL Speed = Full Load Speed (Rpm)Sync Speed = Synchronous Speed (Rpm)

ReflectedWK2 =

WK2 of Load

(Reduction Ratio)2

horsepower formulas

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