Appalachian Fluid Power, Inc.
3364 State Route 31
Acme, PA 15610
Ph. 724-593-8333Fx. 724-593-8334
Rules of Thumb

Horsepower for driving
a pump:
For every 1 HP of drive, the
equivalent of 1 GPM @ 1500
PSI can be produced.

Horsepower for idling a pump:
To idle a pump when it is
unloaded will require about 5%
of it full rated horsepower.

Compressibility of
hydraulic oil:
Volume reduction is approx 
1/2% for every 1000 PSI of
fluid pressure.

Compressibility of water:
Volume reduction is about
1/3% for every 100 PSI of
pressure.

Wattage for heating
hydraulic oil:
Each watt will raise the temp.
of 1 gallon of oil by 1 degree
Fahrenheit per hour.

Flow velocity in hyd. lines:
Pump suction lines 2-4 fps.
Pressure lines up to 500 PSI,
10-15 fps.
Pressure lines 500-3000 PSI,
15-20 fps.
Pressure lines over 3000 PSI,
25 fps.
All oil lines in air-over-oil
systems, 4 fps.

Safe pump inlet vacuum:
Gear Pumps
3-5 PSI or 6-10 In. HG
Vane Pumps
2-3 PSI or 4-6 In. HG
Piston Pumps
2 PSI or 4 In. HG
            "hydraulics and pneumatics... it's what we do"
Abbreviations

abs - absolute
AC - alternating current
Btu - British thermal unit
C - degrees Celsius
cc - closed center
ccw - counter clockwise
cfm - cubic ft per minute
cfs - cubic ft per second
cir - cubic inches per rev.
cim - cubic inches per min.
com - Common
cpm - cycles per minute
cps - cycles per second
cw - clockwise
cyl - cylinder
DC - direct current
dia - diameter
disp - displacement
ext - external
F - degrees Fahrenheit
fl - fluid
fpm - feet per minute
ft - foot
ft-lb - foot pound
gal - gallon
gpm - gallons per minute
HP - horsepower
ID - inside diameter
in - inch
in-lb - inch pound
int - internal
ipm - inches per minute
ips - inches per second
lb - pound
NC - normally closed
NO - normally open
NPT - national pipe thread
NPTF - dryseal pipe thread
oc - open center
OD - outside diameter
P.O. - pilot operated
PSI - lb per square inch
psia - psi absolute
psig - psi gauge
r - radius
rpm - rev. per minute
rps - rev. per second
sol - solenoid
T - torque
vac - vacuum
visc - viscosity
Conversions

Length - 1 inch = 25.4mm
Pressure - 1 bar = 14.5 PSI
Flow - 1 GPM = 3.79 l/min
Force - lb (f) = 4.44 N
Mass - 1 Kg = 2.2 lb (m)
Volume - 1 Gal. - 3.79 liters
Temperature - C = 5/9 (F-32)
Torque - 1 ft-lb - 1.356 Nm
Power - 1 HP = .746 kw
Frequency - 1 Hz = 1 cps
Disp. - 1 ml/rev = 0.061 cir
Other Products Available from AFP
FORMULAS

Hydraulic Power
HP = PSI x GPM / 1714

HP = Horsepower
PSI = Gauge pressure
GPM = Flow

Cylinder Force
F = A X PSI

F = Force, lbs.
A = Piston Area, square inch
PSI = Gauge pressure

Cylinder Travel Speed
S = V / A

S = Travel Speed, in./min.
V = Volume, cubic in./ min.
A = Piston Area, square inch

Velocity
V = GPM x 0.3208 / A

V = Velocity, ft. per sec.
GPM = Flow
A = pipe inside area, sq. inch

Heat of Fluid Power
BTU per hour =
PSI X GPM X 1-1/2

BTU = British thermal unit
PSI = Gauge pressure
GPM = Flow