PISTON AND SYSTEM FLUID SPEED RELATIVE TO PORT SIZE
AND CUSHION REQUIREMENTS
Page 27
FORCE AND FORCE REDUCTION CHARTS
PISTON / FLUID VELOCITY
SERIES
C
The chart to the right provides a guide in determining the adequacy
of standard cylinder ports relative to application. The information provides
piston speed in feet per minute, by bore size for standard NPTF ports, sys-
tem connected using Schedule 80 pipe with a fluid velocity of 15 feet per
second.
Piston speed is a function of fluid velocity in the connecting lines,
generally expressed in gallons per minute (GPM) and measured as the
input/exhaust flow through the cylinder cap end port.
System fluid velocity should not exceed 15 feet per second in order
to minimize the effect of fluid turbulence, pressure drop and hydraulic shock
loading. If fluid velocity through the cylinder ports exceeds 15 feet per sec-
ond, consider port enlargement or twin ports.
Circumstances involving heavy loads or piston speeds in excess of
20
feet per minute wherein the piston completes full stroke, cushions are
recommended. Cylinder cushions increase cylinder life, reduce piston im-
pact speeds and hydraulic shock.