Entwistle - Hydraulic Distribution Division

Kenett Hydraulic Distribution Division

Useful Conversion Factors...

VOLUME:

1 gallon = 231 in.³
1 gallon = 3.785 liters
1 liter = 61.02 in.³

LENGTH:

1 inch = 25.4 mm
1 meter = 39.37 inches
1 micron = .000039 inches

PRESSURE:

1 bar = 14.5 PSI
1 atmosphere = 14.7 PSI
1 kg/cm² = 14.2 PSI
1 in-hg = .4912 PSI
1 bar - 100 kpa
1 PSI = 6.89 kpa

POWER:

1 HP = 1.014 metric HP
1 HP = .7457 KW
1 HP = 42.4 BTU/min.
1 HP = 2545 BTU/Hr.
1 HP = 550 ft - lb/sec

SPEED:

1 ft/sec = 0.3048 M/sec

FORCE:

1 N (newton) - 0.2248 lbs.

USEFUL DATA

OIL COMPRESSABILITY:

For every 1000 PSI there is a reduction in oil volume of 1/2%

OIL TEMPERATURE:

Oil temperature should never be allowed to exceed 140°F

PUMP MOUNTING:

Hydraulic pumps should never be mounted higher than 3 feet above the minimum oil level in the reservoir

PUMP & MOTOR CASE DRAINS:

Most pump or motor case drains cannot exceed 15 PSIG

VISCOSITY AT START-UP:

Maximum viscosity at start-up ranges from 1000 for inline piston pumps to 4000 SUS for gear and vane eqiupment

HORSEPOWER INPUT TO PUMP:

1 HP = 1 GPM at 1500 PSI

ENTRAINED AIR:

At room temperature standard hydraulic oil contains 8-9% air by volume

FLOW VELOCITIES:

Suction lines 2-4ft/sec
Return lines 10-15 ft/sec
Working lines (500 to 3000 PSI) 15 to 20 ft/sec
Working lines (3000 to 5000 PSI) 20 to 30 ft/sec

HEAD PRESSURE:

Oil creates a pressure due to its weight of 0.4 PSI per foot of depth

REQUIRED FLOW RATE:

a) For cylinders:

A = area in (in²)
V = velocity in (in/min.)

b) For motors:

GPM = D x RPM

231

D = displacement in (in³)/rev