Section II - Description
8
Quincy Compressor-QSI
®
Capacity Control System
As the motor starts driving the compressor rotors, air is
drawn in, compressed and discharged into the air/fluid
reservoir. When the air pressure in the air/fluid reservoir
exceeds the set point of the pilot valve (normally 110
PSIG), the valve opens and passes a controlled volume of
air to the inlet valve air cylinder.
NOTICE!
Other pressures are available optionally.
The air forces a piston to move within the cylinder,
closing the inlet valve. The compressor will continue to
run, matching air demand with air delivery by constantly
adjusting the position of the inlet valve. The inlet valve
regulates compressor capacity between 100% and nearly
0% of rated delivery.
When maximum pressure (typically 10 PSIG above
normal full load pressure) has been obtained in the air
system, complete compressor unloading occurs. The
pressure switch located in the control panel sends a signal
to the control and the solenoid valve opens, venting the
residual pressure from the blowdown valve. At the same
time, control air from the reservoir check valve is
directed through the solenoid to the inlet valve air
cylinder. The inlet valve is held in a closed position
preventing the intake of air into the compressor and
serving as a check valve preventing reverse air/fluid flow
through the inlet valve and air filter.
Auto/Dual (Standard)
The Auto/Dual system offers two choices of controlling
the Quincy QSI Compressor. With the selector switch in
the Continuous Run position, the compressor operates
continuously, matching air demand as the differential
pilot valve controls the position of the inlet valve. When
maximum system pressure is reached, the pressure switch
opens, venting the air/fluid reservoir and, although the
compressor continues to run unloaded, no air is
compressed.
When the Auto Dual mode is selected, the compressor
will also perform as above; however, a solid state timer is
activated when the pressure switch contacts open. This
timer is adjustable within a ten (10) minute range. When
the timer reaches the end of its delay period, the
compressor will automatically shut down and assume a
“standby” mode. Upon a drop in system air pressure, the
pressure switch contacts close, restarting the compressor
automatically. The timer should be set, during unit start-
up, for a minimum of six (6) minutes.
During the unloaded/timing mode, if plant pressure
should drop causing the pressure switch contacts to close,
the compressor will continue to operate, resetting the
timer and instructing the inlet valve to reopen.
Summary of Contents for QSI 1000
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Page 11: ...Section I General Quincy Compressor QSI 5 MODEL IDENTIFICATION ...
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Page 66: ...Appendix A Dimensional Drawings 60 Quincy Compressor QSI QSI 220 245 air cooled ...
Page 67: ...Appendix A Dimensional Drawings Quincy Compressor QSI 61 QSI 220 245 water cooled ...
Page 68: ...Appendix A Dimensional Drawings 62 Quincy Compressor QSI QSI 250 300 air cooled ...
Page 69: ...Appendix A Dimensional Drawings Quincy Compressor QSI 63 QSI 250 300 water cooled ...
Page 70: ...Appendix A Dimensional Drawings 64 Quincy Compressor QSI QSI 335 370 air cooled ...
Page 71: ...Appendix A Dimensional Drawings Quincy Compressor QSI 65 QSI 335 370 water cooled ...
Page 72: ...Appendix A Dimensional Drawings 66 Quincy Compressor QSI QSI 440 500 air cooled ...
Page 73: ...Appendix A Dimensional Drawings Quincy Compressor QSI 67 QSI 440 500 water cooled ...
Page 74: ...Appendix A Dimensional Drawings 68 Quincy Compressor QSI QSI 540 600 air cooled ...
Page 75: ...Appendix A Dimensional Drawings Quincy Compressor QSI 69 QSI 540 600 water cooled ...
Page 76: ...Appendix A Dimensional Drawings 70 Quincy Compressor QSI QSI 675 750 air cooled ...
Page 77: ...Appendix A Dimensional Drawings Quincy Compressor QSI 71 QSI 675 750 water cooled ...
Page 78: ...Appendix A Dimensional Drawings 72 Quincy Compressor QSI QSI 925 1000 air cooled ...
Page 79: ...Appendix A Dimensional Drawings Quincy Compressor QSI 73 QSI 925 1000 water cooled ...
Page 80: ...Appendix A Dimensional Drawings 74 Quincy Compressor QSI QSI 1175 1250 1400 1500 air cooled ...
Page 81: ...Appendix A Dimensional Drawings Quincy Compressor QSI 75 QSI 1175 1250 1400 1500 water cooled ...
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