Basic HTML Version
Page 154 • Catalog 207
727-446-1656 • 1-800-446-1656 • www.depcopump.com
TOTAL DIFFERENTIAL HEAD (TDH)
System Head =
total discharge head - total suction head
H = h
d
- h
s
h
d
= h
sd
+ h
pd
+ h
fd
h
s
= h
ss
+ h
ps
= h
fs
where:
h
d
= total discharge head
h
s
= total suction head
h
sd
= discharge static head
h
ss
= suction static head
h
pd
= discharge surface pressure
h
ps
= suction surface pressure
h
fd
= discharge friction head
hfs = suction friction head
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 inlet nozzle.”
h
sv
= h
sa
- h
ypa
where:
h
sv
= available net position suction head, in feet of liquid
h
sa
= total suction head, in feet of liquid, absolute
h
ypa
= vapor pressure of liquid at suction nozzle, in feet of liquid, absolute
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
VISCOSITY
Centistokes x 4.64 = SSU(approx.)
Centipoises x Sp. Gr. = Centistokes
POWER
BHP
= GPM x TDH x sp. gr. (for centrifugal pumps)
3960 x Eff.
BHP
= GPM x PSI (for positive displacement pumps)
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
E(volts) x I(Amps)746
I(amps)
= HP x 746
E(volts) x Eff. X P.F. x 1.732
HELPFUL PUMP RELATED FORMULAS
TEMPERATURE
Conversion
:
°C = 5/9 (°F - 32)
°F = 9/5°C + 32
SPECIFIC GRAVITY
sp. gr. = weight of liquid
weight of water
weight of water = 62.4 Lb./cu. ft
8.3 Lb./gal.
COMMON O-RING / ELASTOMER
MATERIAL PROPERTIES
Buna-N
- Temp range 10° F – 180° F
- Good for most petroleum products
Viton
- Temp range -20° F to 350° F
- Good for aromatic/chlorinated hydrocarbons
and most acids
EPDM
- Temp range -40° F to 250° F
- Good for caustics and some milder acids
Neoprene
- Temp range 0° F to 180° F
- Good for water and non-aggressive, dilute fluids.
Best for food contact.