Formulas, Laws, Conversions and Related Data

TOTAL DIFFERENTIAL HEAD (THD)

System Head = total discharge head - total suction head

H = hd - hs

 

hd = hsd + hpd + hfd hs = hss + hps = hfs
where:
hd = total discharge head hs = total suction head
hsd = discharge static head hss = suction static head
hpd = discharge surface pressure hps = suction surface pressure
hfd = discharge friction head hfs = suction friction head

 

 

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AVAILABLE NPSH

Available NPSH is "the difference between the total suction head and the vapor pressure of the liquid, in feet of liquid, at the suction flange."

hsv = hsa - hypa


where:

hsv = available net position suction head, in feet of liquid

hsa = total suction head, in feet of liquid, absolute

hypa = vapor pressure of liquid at suction nozzle, in feet of liquid, absolute

 

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PRESSURE Conversion:

Head (ft.) = psi x 2.31 / sp. gr.

PSI = head (ft.) x sp. gr. / 2.31

Lbs./sq. in. = In. of Mercury x .491
Lbs./sq. in. = Atmospheres x 14.7

mm hg. = Atmospheres x 760

 

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VISCOSITY

Centistokes x 4.64 = SSU(approx.)

Centipoise Sp. Gr. = Centistokes

 

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FLOW

Gallons per minute (GPM) x 3.785 = Leters per minute

 

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TEMPERATURE Conversion:

°C = 5/9 (°F - 32)

°F = 9/5°C + 32

 

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SPECIFIC GRAVITY

sp. gr. = weight of liquid
sp. gr. = weight of water

weight of water = 62.4 Lb./cu.
weight of water = 8.3 Lb./gal.

 

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AFFINITY LAWS

 

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POWER

BHP = GPM x TDH x sp. gr.
BHP = 3960 x Eff.

BHP = GPM x PSI
BHP = 1715 x Eff.

KW = 0.746 x H.P.

Torque = (Ft. Lb.) = HP x 5260
Torque = (Ft. Lb.) = RPM

HP = E(volts) x I(Amps) x Eff. X P.F. x 1.732
HP = E(volts) x I(Amps)746

I(amps) = HP x 746
I(amps) = E(volts) x Eff. X P.F. x 1.732

 

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O-RING TEMPERATURE LIMITATIONS

Material[Code]
Temperature Limits

Modified Polytetrafluorethylene [TM]
Low: -100 °F (-73 °C) High: 300 °F (149 °C)

Viton [VA]
Low: -20 °F (-29 °C) High: 400 °F (204 °C)

Perfluoroelastomer (Kalrez) [KAL]
Low: -36 °F(-38 °C) High: 550 °F (287 °C)

 

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PROPERTIES OF WATER

Temp Specific Vapor Pressure
Degrees °F Gravity Ft. of H2O In. Hg In. Hg Vac
60 1.000 0.6 0.53 29.39
100 0.994 2.2 1.94 27.98
150 0.982 8.8 7.76 22.16
200 0.965 27.6 24.36 5.56
210 0.961 33.9 29.92 0.00
212 0.959 35.4 31.33  

 

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