Quincy QPNC 100, Parts And Instruction Manual

8

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 R404A

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)

R404A

74 - 76

(4.3 - 4.5)

2

1

FIGURE 10 — 
BYPASS VALVE