SPX Waukesha Cherry-Burrell Votator II, Operation And Maintenance Manual

Page: 82 / 84

Troubleshooting Waukesha Cherry-Burrell
Page 82 95-03057 October 2005
Unthawing A Frozen System
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 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.
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 for cause and
solution aids.
Water and Air in Refrigeration System
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.