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 TM 55-1905-220-14-8
4-30. CONDENSER - AIR CONDITIONING - MAINTENANCE INSTRUCTIONS (Continued).
a. Water supply and Operating Pressures.
(1) The discharge or head pressure at which the compressor operates is determined by the temperature
and quantity of cooling sea water circulated through the condenser. Keep the cooling water quantity at the
minimum necessary to maintain the refrigerant head pressure between 90 and 125 psig (620.5 to 861.9 kPa).
A minimum amount of water will prolong condenser tube life (by reducing water velocities) and will lessen the
frequency of cleaning and repairs. However, do not operate the system in excess of 125 psig (681.9 kPa) head
pressure.
(2) Adjust the condenser water regulating valve to automatically maintain the desired head pressure. If
a water regulating valve is not installed, control the flow of condenser water by throttling a valve in the
condenser water outlet line. As a general rule, the quantity of condenser water should not exceed 6 gpm (22.71
lpm) per ton of refrigeration.
NOTE
Always supply sufficient water pressure to condenser but do
not exceed 50 psig (344.7 kPa) at water regulating valve.
(a) Low Head Pressure.
Low head pressure may be caused by too much cooling water or too low water temperature. If
head pressure drops below 90 psig (620.5 kPa), decrease water flow through condenser. Refer to
troubleshooting in Volume 3 for other possible causes of low head pressure.
(b) High Head Pressure.
Head pressure may rise above 125 psig (861.9 kPa) for several reasons:
1 Condenser water flow may be insufficient or water temperature may be high. High water
temperatures often exist in tropical climates. Adjust water regulating valve or condenser
water outlet valve to increase water flow and maintain 125 psig (861.9 kPa) or less head
pressure.
2 Air or other noncondensable gases may be present in the refrigerant side of the condenser. If
head pressure rises above 125 psig (861.9 kPa), and maximum water flow when sea water
temperature is below 88 (31.1 ) does not reduce pressure to normal, test for
F
C
noncondensable gases.
4-943
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