Unthawing A Frozen System; Water And Air In Refrigeration System - SPX Votator II Instruction Manual

Troubleshooting
Unthawing A Frozen
System
Water and Air in
Refrigeration System
Page 82
Waukesha Cherry-Burrell
To unthaw a system that has frozen-up, perform the following
procedures. The cause of freeze-up MUST BE corrected before
operation is restarted. See the Troubleshooting Chart starting on
page 79 for cause and solution aids.
1. Turn refrigeration or coolant source OFF.
2. Heat mutator shaft with shaft heater attachment using hot
water (if applicable).
3. Cautiously pump hot water or hot product through unit.
Immediately shut down pump if excessive pressure is
encountered. If hot gas defrost line is connected, thaw by
blowing hot gas through the jacket
4. Continue pumping until shaft can be rotated by bumping the
motor.
5. Severe freeze-ups may necessitate disassembly of
equipment to remove blockage.
6. Resume normal start-up procedure. The cause of freeze-up
MUST BE corrected before operation is restarted. See the
Troubleshooting Chart on page 79 for cause and solution
aids.
Water and ammonia combine to form ammonium hydroxide,
which combines with oil to form sludge. Sludge is extremely
difficult to remove.
Water condenses at the accumulator's pressure and temperature
and remains to dilute the liquid ammonia. Ammonia diluted with
water has a higher boiling point that requires lower back pressure
to achieve the desired refrigerant temperature.
Air in ammonia increases the compressor head pressure and
increases the gas discharge temperature. Higher head pressure
and temperature may carbonize or vaporize oil. Air also contains
moisture that the ammonia refrigerant absorbs.
To avoid difficulties with water and air:
• Regularly purge refrigeration system of air and
noncombustible gases. An automatic air purger in the system
is recommended.
• Grease all valve stems to keep packing soft. Soft packing
allows a better seal to prevent leakage of air past stems, if
the systems ever separate on a vacuum.
• Tighten up stuffing boxes to seal out air and moisture.
• Avoid operating system on a high vacuum.
95-03057 11/2012