Farr HD8625, Technical Manual

Page: 155 / 156

T
echnical
M
anual
hD8625 8-
5
/
8
” 35K T
ong
7.31
h
yDraulic
c
oMponenTs
Pilot-to-open, spring biased closed, unbalanced
poppet logic element
Capacity:
60 gpm (240 L/min.)
Functional Group:
Products : Cartridges : Corrosion Resistant : Logic Element : Unbalanced Poppet,
Pilot-to-open, Switching Element, Spring biased closed, External Pilot Port 3
pilot source
Model:
LKHC
Product Description
These unbalanced poppet, logic valves are 2-way switching elements that are
spring-biased closed. Pressure at either work port 1 or 2 will further bias the
valve to the closed position while pressure at port 3 will tend to open it. The
force generated at port 3 must be greater than the sum of the forces acting at
port 1 and port 2 plus the spring force for the valve to open. NOT
E
: The pilot
area (port 3) is 1.8 times the area at port 1 and 2.25 times the area at port 2.
Technical Features

B
ecause these valves are unbalanced,
operation is pressure dependent.
Opening and closing of the poppet are
functions of the force balances on three
areas: 1) Port 1 = 100%, Port 2 = 80%,
and Port 3 = 180%.

These valves are pressure responsive
at all three ports, therefore it is
essential to consider all aspects of
system operation through a complete
cycle. Pressure changes at any one
port may cause a valve to switch from a
closed to an open position, or vice
versa. All possible pressure changes in
the complete circuit must be considered
to assure a safe, functional system
design.