Quincy Compressor QPNC 10 Operator's Manual - Start-Up and Operation

8

Pub. No. 2200772355 — October 2006

START-UP AND OPERATION

PRELIMINARY CONTROLS

Before starting the dryer, check for:

1.

The correct connection to the compressed air piping: 

remember to remove end caps on the dryer inlet and 

outlet.

2.

The correct connection to the condensate drainage 

system.

3.

The correct power supply.

STARTING AND STOPPING

Always start the dryer at least 5 minutes before the air 

compressor starts running and stop it after the air 

compressor has been stopped in order to keep the 

compressed air piping free of condensate. The dryer must 

be kept running while the air compressor is running. 

PRESSURE DISCHARGE PROCEDURE

See Figure 13 on Page 10.

1.

Isolate the dryer from the air system (1).

2.

Release the pressure in the dryer by pressing the 

condensate drain “TEST” pushbutton located on the 

auto drain (2).

3.

Switch off the machine by turning the STOP button to 

position “0 OFF” (3).

4.

Turn off the power supply by opening the circuit 

breaker or fused disconnect switch (4).

CALIBRATIONS

HOT GAS BYPASS VALVE

These valves have already been calibrated and they do 

not require any adjustment. A dew point different from the 

rated one generally is caused by factors which are not 

attributable to their operation. Figure 10 shows:

1.

Closing cap

2.

Adjusting screw

This valve maintains the 

refrigerant suction pressure in 

varying load conditions. The 

dryer will run from no load to 

full load conditions without 

freeze-up. The operation of this 

valve is automatic. If the valve 

needs adjustment, turn the 

adjusting stem clockwise to 

raise the suction pressure, and 

counterclockwise to lower the suction pressure. This 

adjustment should be made under a no-load condition if 

possible. When the adjustment is made, turn one quarter 

of a turn at a time, and wait 3 to 5 minutes between 

adjustments. Careful adjustment of this valve is necessary 

for normal operation of the air dryer. Hot gas bypass 

valve adjustment may be made by maintenance 

personnel. (See Figure 10.)

Table 2 — WORKING PRESSURES AND 

TEMPERATURES OF R134A

Before making any change to the machine,

ensure that the electric power supply has

been disconnected. Wait at least two hours

before starting up after any machine

movement (transport or handling).

The following procedure must be per-

formed by skilled personnel approved by

the manufacturer.

If the dryer is switched off, before starting

it again, wait at least 5 minutes to allow

for pressure balancing.

SUCTION SIDE OF

REFRIGERATION COMPRESSOR

Evaporating 

Temperature

°F (°C)

Evaporating 

Pressure

psi (bar)

RATED VALUES 

AT AMBIENT 

TEMPERATURE 

+68 °F (+20 °C)

33.8 - 35.6

(1 - 2)

R134A

29 - 31

(2.1 - 2.3)

2

1

FIGURE 10 — 

BYPASS VALVE