Sullair RD Series, User & Service Manual

Page: 15 / 268

SECTION 2 RH SERIES—HIGH TEMPERATURE
15
2.5 REFRIGERANT DRYER
FEATURES
2.5.1 C
OMPRESSOR
T
YPE
The High Temperature Inlet Refrigerated
compressed air dryers use the sealed Hermetic type
of compressors and require no periodic servicing.
2.5.2 C
ONDENSER
The air-cooled condenser is equipped with
helicoidally fans controlled by a pressure switch the
controls the fan cycling in order to maintain the
refrigerant high pressure at the correct level.
Air cooled aftercooler is integrated to the condenser.
The fan motor of the air cooled aftercooler is
separate and it only starts to function when the inlet
air temperature is equal or above 95°F. This is
controlled by a thermostatic switch.
2.5.3 R
EFRIGERANT CIRCUIT PROTECTION
O
VERLOAD PROTECTOR
:
The single phase compressors are equipped with an
overload protector which is a thermal sensitive
switch controlling the temperature of the compressor
and overheating. In case of malfunction, the
protector trips out. However, it switches on again
automatically as soon as the compressor has cooled
down.
H
IGH PRESSURE SECURITY SWITCH
:
Refrigerant circuits are protected against excessive
pressure by a security switch that stops the
compressor in case of too high a pressure. In case
this safety switch has tripped, it has to be manually
reset before switching on the dryer.
2.5.4 F
ILTER DRYER
In order to keep the refrigerant circuit void of all
moisture, a filter drier is used in line. This filter also
traps any solid particles that may have migrated in
the circuit during operation. To avoid problems, the
refrigerant circuit must be vacuumed before filling it
with the recommended refrigerant.
2.5.5 R
EFRIGERANT CIRCUIT REGULATION
1. The evaporating pressure is kept constant
by controlled injection of hot gas from the
high-pressure side into the low-pressure
section of the circuit through a by-pass valve.
This constant pressure corresponds to a sta-
ble evaporating temperature adjusted as
close to 32°F as possible.
2. The liquid refrigerant is injected into the
evaporator through a thermostatic expansion
valve keeping the superheat of the refriger-
ant constant at the outlet of the evaporator.
3. The mix of hot gas from by-pass valve and
cold gas from evaporator is called superheat.
2.5.6 C
ONDENSATE DRAIN
—
TRAP ASSEMBLY
Disassembling the drain is easy because it can be
isolated from the air circuit under pressure with a ball
valve. The drain has to be isolated before being
dismantled.