Differential Pilot Valve; Pressure Setting - Quincy QSI-90 Instruction Manual

Section V - Servicing

Differential Pilot Valve

WARNING!
Never adjust the pressure higher than
the factory setting. Death or serious
injury and compressor or property
damage could result.
Open a manual vent valve to allow the
compressor to exhaust air to the outside
and start the unit. By manual regulation,
slowly close the valve, allowing the
unit to build air pressure to the desired
modulation point and hold (100 PSIG
standard). Adjust the screw on the bottom
of the differential pilot valve so that a slight
stream of air can be felt coming from the
orifi ce adjacent to the adjustment screw.
When the air is felt, air is beginning to pass
through the pilot valve to the air cylinder

Pressure Setting

The pressure setting determines what
pressure the compressor will load and
unload. Standard factory settings are listed
in the QSI Specifi cations. If a lower setting
is desired, adjust the differential pilot valve
fi rst and set the pressure cut-out point to
15 PSIG over the desired full load pressure.
Refer to HMI Control Panel Operation in
40
on the inlet valve, causing the valve to
modulate toward its closed position,
thereby reducing the volume of air being
compressed.
To raise the pressure, turn the adjusting
screw in (clockwise). To lower the pressure,
turn the screw out (counter clockwise).
Maximum full load pressure is 125 PSIG
for standard QSI units. Minimum full load
pressure with modulation and standard
controls is 100 PSIG.
NOTICE!
Although temporary operation
pressure can be as low as 75 psig,
continuous operation below 100
psig will cause an increase in
fluid carryover.
Section IV for instructions on adjusting the
pressure settings. The pressure settings
should unload the compressor by the time
it reaches the 20% load point. Raising the
pressure without changing the compressor
speed above factory settings will result in
high amp draw.