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Parker Hannifin Corporation
Parflex Division
Ravenna, Ohio
272
Hydraulic &
Pneumatic
Hose & Fit.
PTFE
Hose &
Fittings
Thermoplastic
Tubing
Coiled Air Hose,
Fittings
& Accessories
Truck (Fleet)
Products
Tooling &
Equipment
Hose
Accessories
Technical &
Design
Information
Approvals &
Guides
Alphanumeric
Index
The Fluid Velocity Nomogram gives the velocity of a liquid or gas as a function of flow rate and inside diameter
of the fluid line. The commonly recommended maximum velocities for hydraulic oil systems at 200°F or less
are indicated for guidance.
Example: At 10 gpm, what is the minimum size within the recommended velocity range
for a hydraulic pressure line?
The dashed line drawn from the 10 gpm mark on the left hand line to the maximum velocity of 20 fps inter-
sects the middle line at .438 " (7/16" I. D. hose or tubing).
For a hose application, use 1/2" I. D., the nearest common standard size.
This chart is based on the following formulas:
v
fps
= .321Q , Q = gal per min
þd
2
d
= hose or tube I. D. (inch)
4
Selection of Hose Diameter from Flow Rate and Velocity
Selection of Hose Diameter
cu. ft./min. = .1337 Q
The cu. ft. per min. value is the actual
volume flow rate under flowing condi-
tions.
For air, standard cfm of free air = 7.81
actual cfm when the inlet air is at 100
PSIg, 68°F.