QR 325
Quincy Compressor
50215-106, January 2014
27
3501 Wismann Lane, Quincy IL - 62305-3116
WARNING !
Installation
The pilot valve is to be connected to the air receiver
using a minimum of 3/8" o.d. copper tube. Compres-
sors in the field, not equipped with a suction valve
unloader assembly, can be converted to constant speed.
Consult your local Quincy distributor for assistance
with conversion procedures.
Service
Periodically check the filter & screens in the inlet of
the pilot valve to make sure they are free of obstruc-
tions. If they become clogged, remove and clean or
replace. Inspect the "o"ring located in the opposite end
of the pilot valve body for wear or damage; replace if
necessary.
Adjustment
The unloading pressure is adjustable and is regulated
by turning the hex nut (marked "unload adj." in cross
sectional illustrations of pilot valves). Turn the hex
nut clockwise to increase and counterclockwise to
decrease the unloading pressure.
The differential (difference between unloading
and loading pressure) is set by turning the hex nut
marked "differential adjustment" in the illustrations
of the pilot valves on previous pages. Increase the dif-
ferential pressure by turning the hex nut clockwise
- decrease by turning counterclockwise. Tighten the
locknuts after adjustment.
SUCTION VALVE
UNLOADER ASSEMBLIES
Description
The Quincy suction valve unloader assembly consists
of unloading arrangements on the suction valves,
having a plunger to contact the suction valve disc
and an unloader pilot valve to automatically regulate
the passing of receiver pressure to the unloading ar-
rangement.
Application
Suction valve unloader assemblies are recommended
for use on Quincy compressors where the compressor
is to run continuously and a constant pressure is to be
maintained. The purpose is to automatically unseat
the suction valve of the compressor when the air
supply is greater than the demand.
Operation
Unloading occurs when receiver pressure is sufficient
to overcome pilot valve spring pressure. The check
ball is then unseated, allowing receiver pressure to
pass to the unloading arrangements. The compressor
will run unloaded until the receiver pressure drops
to a predetermined level. At this time, the action of
the ball is reversed, shutting off receiver pressure to
the unloader arrangement and venting the unloader
to atmosphere. This allows the compressor to load.
The drive, either electric motor or combustion engine,
runs continuously and must be started and stopped
manually.
The LS control version is equipped with a toggle
lever on the pilot valve which can be flipped to provide
manual unloading.
The LVD control version is designed to provide a
choice between "start/stop" or "continuous run" opera-
tion. The LVD pilot valve can be set for "start/stop"
operation by turning the knurled knob at the end of
the pilot valve clockwise until it stops. Under these
circumstances a pressure switch is required to stop
the motor. Failure to use a pressure switch, with the
pilot valve locked out, could result in unsafe conditions.
A pressure switch must be incorporated whenever an LVD
pilot valve is employed as part of the control system.
The compressor will operate in the continous run
mode if the knurled knob on the LVD pilot valve is
turned counterclockwise until it stops.
