32
installation
Moisture and air impede proper
compressor and system functioning,
reducing service life by increasing
condensing pressure and presenting
risk of acid formation.
High condensing pressure brings
abnormally
high
discharge
temperatures that degrade the oil's
lubricating properties. Acid formation
can lead to copper plating. These
undesirable phenomena may cause
both mechanical and electrical
compressor failures. The typical
method for avoiding such problems
is pump-down with a vacuum pump,
to a minimum vacuum of 500 microns
(0.67 mbar). Please refer to Bulletin
"Vaccum pump down and dehydration
procedure".
Initial charging must be done in the
liquid phase as far away from the
compressor as possible, with the
compressor stopped and service
valves closed. The best location for
charging is on the liquid line between
condenser outlet filter drier.
Charge as close as possible to the
nominal system charge before
starting the compressor. Add charge
in liquid phase as needed during
commissioning,
slowly
throttling
liquid in on the low pressure side as far
away as possible from the compressor
suction connection. The refrigerant
charge quantity must be suitable for
both summer and winter operations.
The system must be monitored after
initial start-up for a minimum of 60
minutes to ensure proper operating
characteristics such as:
•
Proper metering device operation
and desired superheat readings,
•
Suction and discharge pressure
within acceptable levels,
•
Correct oil level in compressor sump,
indicating proper oil return,
•
Low foaming in sight glass and
compressor sump temperature 18°F
above saturation temperature to show
that there is no refrigerant migration
taking place,
•
Acceptable cycling rate and run time
duration,
•
Current draw of individual compres-
sors within acceptable values (RLA
ratings),
•
No abnormal vibrations or noise.
Always use the original oil specified by
Danfoss as shown on page 33. Use oil
from new cans only.
Top-up the oil while the compressor
is running. Use the schrader con-
nector and a suitable pump or any
other accessible connector on the
compressor suction line. See Bulletin
"Lubricants, filling in instructions for
Danfoss Commercial Compressors".
please note that sZ and sY use
different viscosity poe oil, danfoss
160sZ and 320sZ respectively.
When the compressor running
conditions are stabilized, the oil level
must be visible in the sight glass.
The presence of foam in the sight glass
undicates a large concentration of
refrigerant in the oil, presence of liquid
returning to the compressor, or both.
The oil level can also be checked a few
minutes after the compressor stops,
the level must be between 1/4 and 3/4
of sight glass.
When compressor is off, the level
in the sight glass can be influenced
by the presence of refrigerant in
the oil
.
Vacuum pump-down and
moisture removal
Refrigerant charging
commissioning
oil top-up
oil level checking and
top-up
oil level check
Summary of Contents for Performer SM 084
Page 39: ......
