Section 8
DRYER OPERATION
29
8.1 GENERAL
While Sullair has built into this compressor/dryer
controls and indicators to assist you in determining
if it is operating properly, it will be necessary to rec-
ognize and interpret the condition which will call for
service or indicate the beginning of a malfunction.
Before starting the Sullair compressor/dryer, read
this section thoroughly and familiarize yourself with
thecontrolsandindicators --- theirpurpose,location
and use.
8.2 PURPOSE OF CONTROLS
CONTROL OR INDICATOR PURPOSE
REFRIGERANT SUCTION PRESSURE GAUGE Indicates the refrigerant pressure as it enters the com-
pressor. Before start---up, it is equivalent to the ambient
temperature converted to pressure e. g. at 70_F(21_C)
ambient temperature, R---22 suction pressure is 121 psig
(8.3 bar) (See Figure 8---1, Temperature Pressure Chart).
8.3 INITIAL DRYER START--UP PROCEDURE
After the installation has been completed, the fol-
lowing items should be checked.
1.Checkmainelectricalsupplyforproperinputvolt-
age.
CAUTION
!
Make certain that a ll shut---off valves in the refrig-
erant circuit are open. Starting the dryer with a
valve closed could burn up the refrigerant com-
pressor. Rotate valve clockwise to open. Do not
backse at the shut --- off va lve s . If the shut --- of f valve
is backseated the refrigerant pressure signal to
the gauges will be restricted.
2. Turn on the power switch to the dryer, which is
located in the air compressor control panel. The
power indicating light will be on.
CAUTION
!
ES---8 Integral Dryers are not equipped with a
crankcase heater. Installation of these compres-
sor/dryersin areaswithambient temperaturesbe-
low 65_F(18_C)canresultincompressordam-
age.
3. Check the refrigerant suction pressure. This
should be checked with no air flowing through
the compressor/dryer, with a head pressure of
170 psig (11.7 bar), and without t he condenser
fan cycling.
a) The suction pressure should be 58---60 psig
(4.0 to 4.1 bar). It is normal for the dryer to
cycle between these pressures. During this
cyclin g the suction pressure should not fall
below58psig(4bar).
b)Ifthefancyclesduringthecheckingofthesuc-
tion pressure, a jumper wire may be installed
around the fan cycling switch to temporarily
prevent cycling.
c) To achieve the proper head pressure for
checking the suction pressure, t he following
should be done. To increase the head pres-
sure increase the ambient air t emperature or
temporarily restrict the air flow to t he con-
denser.Toreducetheheadpressure, theam-
bient temperature must be reduced.
d) Allow the dryer t o run at least 15 minutes for
stabilizationwhencheckingandadjustingthe
suction pressure.
e) If necessary, adj ust the hot gas bypass valve
(HGBV)tochangethesuctionpressure. Turn
clockwise to increase the suction pressure
and counterclockwise to decrease the suc-
tion pressure.
f) Remove the jumper w ire which wa s installed
around the fan cycling switch in Step “b”
above.
NOTE
If the suction pressure was set or checked at a
head pressure greater than 170 psig (11.7 bar), a
suction pressure lower than 58 psig(4.0 bar) may
result, which could result in evaporator icing.
4.Checktherefrigerant suctionpressure fornormal
operating conditions. See Section 8.5.
a) If necessary, take corrective action as de-
scribed in the dryer troubleshooting section
of this manual (See 10.3 Troubleshooting---
Dryer).
NOTE
The hot gas bypass valve is preset at the factory.
However, it may require readjustment at initial
installation and periodically to help assure the
suction pressure remains in the specified range,
as stated in this Operator’s Manual. If the suction
pressure is too low,icing of the evaporator is pos-
sible.
8.4 SUBSEQUENT START--UP PROCEDURE
1. Turnon the power switch on thecompressor/dry-
er.
2. With the air shutoff valve closed, check the suc-
tion pressure for a normal operating condition. If
itisnotwithinthenormalunloadrangeof58 --- 60
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