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. HgVac

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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