Formulas
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
= 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 = Liters 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
weight of water
weight of water = 62.4 Lb./cu.
8.3 Lb./gal.
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POWER
BHP = GPM x TDH x sp. gr.
3960 x Eff.
BHP = GPM x PSI
1715 x Eff.
KW = 0.746 x H.P.
Torque = (Ft. Lb.) = HP x 5260
RPM
HP = E(volts) x I(Amps) x Eff. X P.F. x 1.732
746
I(amps) = HP x 746
E(volts) x Eff. X P.F. x 1.732
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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 |
|