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 TM 55-1905-220-14-8
4-31. CONDENSER - AIR CONDITIONING - MAINTENANCE INSTRUCTIONS (Continued).
(b) Permanent Tube Repairs.
Replace defective condenser tubes as soon as practicable. Close water valves and drain all water from
condenser. Keep refrigerant gas pressure in condenser higher than water pressure until all water has been
drained. This will prevent water from entering refrigerant side of condenser through leaky tubes. Close
condenser refrigerant inlet and outlet valves and vent remaining refrigerant vapor from condenser shell through
purge valve. Run a line from purge valve to open deck while venting shell. Remove defective tube(s) and
install new tube(s) as described below.
NOTE
Procedures given below for removal and installation of condenser tubes also
apply to replacement of water or brine chiller tubes.
CAUTION
Permanent condenser repairs should be made only by skilled personnel.
1 Removing tubes.
a Thread defective tube on one end with a special knockout plug having a fine "V" buttress
thread. Threads should extend well beyond tube sheet.
b Thin tube wall at each end to about .015 inch thick. For -inch OD tubes, use a 23/32 inch
cutter having a 5/8 inch diameter pilot plug to properly guide and center the cutter. (For 5/8 inch OD tubes, use
a 19/32 inch cutter having a inch diameter pilot plug.) Take care not to damage holes in tube sheet. Stop
cutting tool 1/8 inch from back face of tube sheet to prevent buckling tube when removing it (threaded end
only).
c Turn knockout plug well-into end of tube threaded in step a.
d Insert a 7/16 inch rod into end of tube opposite plug. Rod must be at least a foot longer than
tube. Drive out tube by hammer blows on rod.
4-946
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