Differential Pilot Valve; Pressure Setting - Quincy QGB Series Instruction Manual

Section VI - 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 (00 PSIG
standard). Adjust the screw on the bottom
of the differential pilot valve so that a slight

Pressure Setting

The pressure setting determines what
pressure the compressor will load and
unload. Standard factory settings are
listed in the QGB Specifications. If a lower
setting is desired, adjust the differential
pilot valve first and set the pressure cut-
out point to 5 PSIG over the desired full
load pressure. Refer to HMI Control Panel
Operation in Section IV for instructions
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stream of air can be felt coming from the
orifice adjacent to the adjustment screw.
When the air is felt, air is beginning to pass
through the pilot valve to the air cylinder
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 00 PSIG for
standard QGB
pressure with modulation and standard
controls is 75 PSIG.
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 and drive belt failures. Consult your
parts book for proper sheave and belt part
numbers.
Quincy Compressor-QGB
units. Minimum full load
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