Suction Valve Unloader Assemblies; Decals - Quincy Air Master QT Series Parts Manual

SUCTION VALVE
UNLOADER ASSEMBLIES
Description
The Quincy suction valve unloader assembly consists
of unloading assemblies on the suction valves, having
a plunger to contact the suction valve reed and an
unloader pilot valve (110832 or 110998 series) to
automatically regulate the passing of air tank pres-
sure to the unloading arrangement.
Continuous Run Operation

Suction valve unloader assemblies

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.
Unloading occurs when air tank pressure is suffi-
cient to overcome pilot valve spring pressure. The
check ball is then unseated, allowing air tank pres-
sure to pass to the unloader assemblies. The compres-
sor will run unloaded until the air tank pressure
drops to a predetermined level. At this time, the
action of the ball is reversed, shutting off air tank
pressure to the unloader assemblies and venting the
unloader to atmosphere. This allows the compressor
to load. The drive, either electric motor or engine,
runs continuously and must be started and stopped
manually. 110832 series pilot valves feature a toggle
lever which can be flipped to provide manual unload-
ing.
Dual Control Operation
Dual control operation is designed to provide a
choice between "start/stop" or "continuous run" op-
eration. The 110998 series pilot valve can be set for
"start/stop" operation by turning the knurled knob at
the end of the pilot valve (refer to
110998 series 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, will result in
unsafe conditions.
WARNING !
A pressure switch must be incorporated whenever 110998
series pilot valve is employed as part of the control system.
The compressor will operate in the continuous run
mode if the knurled knob is turned counterclockwise until it
stops.
QT-7.5 Air Master
50121M201, May 2001
Installation
The pilot valve is mounted directly into the air tank. Compres-
sors in the field, not equipped with these controls, can be
converted. Consult your local Quincy Compressor Distributor
for assistance with conversion procedures.
Service
If a change in pilot valve operation is detected, re-
move the pilot valve from the air tank and check the
screen in the inlet of the pilot valve for obstructions.
Clean the screen if necessary.
Adjustment
are recommended
The unloading pressure is adjustable and is regu-
lated by turning the unload adjustment hex nut (refer
to
wise to increase and counterclockwise to decrease the
unloading pressure.
and loading pressure) is set by turning the differen-
tial adjustment hex nut (refer to pilot valve illustra-
tions). Increase the differential pressure by turning
the hex nut clockwise - decrease by turning counter-
clockwise. Make all adjustments in small increments.
Tighten the locknuts after adjustment.

DECALS

illustration for
Item
15
pilot valve illustrations). Turn the hex nut clock-
The differential (difference between unloading
Decals
Part
# Qty. Number
1 1 110831 serial number & nameplate
2 1 127889-A decal, CAUTION!, MANUAL
3 1 127889-B decal, DANGER!,"Air from this...."
3501 Wismann Lane, Quincy IL 62305-3116
Description
Quincy Compressor