filter is used, it should be installed downstream of the re-
frigerated dryer. The dryer will remove some entrained
oil, extending the life of the replaceable filter element.
When a particulate filter is used, it should be installed
upstream of the dryer to keep particulate from fouling
the heat exchangers and improve the reliability of the
automatic drain.
Outlet air temperature may be 10 to 30 degrees higher
than inlet air temperature. This is normal. Consult your
distributor if a lower outlet air temperature is required.
Piping and Connections
Connections to the dryer inlet and outlet can be either
tubing or threaded joints using customer-supplied com-
pression fittings. If joints are soldered, take care not to
damage portions of the dryer with excess heat. Connec-
tions and fittings must be rated for the maximum operat-
ing pressure given on the dryer label and must be in
accordance with applicable codes. See Table I for con-
nection sizes. Inlet and outlet shutoff valves and a valved
bypass are recommended. Support all piping; do not al-
low the piping to place any stresses on the dryer connec-
tions. Piping should be at least the size of the inlet and
outlet connections to minimize pressure drop in the air
system.
Removing Condensate
A separator with an integral automatic drain is supplied
with each dryer. The user must install a separate dis-
charge line at the drain connection to carry off conden-
sate to an environmentally approved condensate
collection/disposal system.
The automatic drain is designed to open periodically and
discharge accumulated condensate into the drain line.
The period between openings varies with operating con-
ditions. Check the operation of the drain trap at least
once per eight-hour operating shift, since it is possible
for pipe scale, oil, grease, sludge and other contaminants
to clog the drain system. If clogging is a problem, install
a strainer or a particulate filter before the dryer to keep
solid particles from entering the dryer. Contact your lo-
cal distributor for the appropriate particulate filter.
Electrical Connections
SDR Series dryers are constructed according to NEMA
Type 1 electrical standards. All models are fitted with a
power cord for 115/1/60 or 100/1/50 power connection.
Refer to figure 2 for electrical schematics.
CAUTION
Operation of dryers with improper line voltage
constitutes abuse and could affect the dryer
warranty.
SDR Series (Bulletin 546)
AIR AND REFRIGERANT FLOW SCHEMATIC
HOW IT WORKS
Airflow
SDR Series dryers use refrigeration cooling to condense
water vapor out of the airstream. Warm saturated air en-
ters the heat exchanger (evaporator/chiller) where it is
cooled by an air-to-refrigerant process. This causes wa-
ter vapor to condense so it can be removed as a liquid.
Condensate is removed from the airstream by a centrifu-
gal separator and discharged from the dryer through an
automatic drain.
The cold, dry air is reheated as it passes through the re-
heater. The reheater reduces the heat that the static con-
denser radiates to the ambient thus eliminating the need
for a cooling fan and preventing pipeline sweating at the
air outlet.
A constant pressure expansion valve modulates the flow
of liquid refrigerant to the chiller. This eliminates
freeze-ups and assures continuous, automatic dew point
control. The valve responds to pressure changes of re-
frigerant leaving the chiller to maintain the proper cool-
ing rate under all load conditions.
The refrigerant valve is adjusted at the factory; operation
is fully automatic.
INSTRUMENTATION
Power On Indicator
Models 7 to 25 scfm: The light located at the plug end
of the power cord indicates when power is supplied to
the dryer.
Figure 3
1-3