TESTING FOR LEAKS
To prevent serious loss of refrigerant through
leaky condenser tubes, test the condenser for
leakage every week. Any condenser that has not
been in use for the preceding 12 hours should also
To test for leaky condenser tubes, drain the
water side of the condenser and let stand for 12
hours, then insert the exploring tube of the leak
detector through one of the drain plug openings.
If this test indicates that R-12 gas is present, you
need to detect the exact location of the leak in the
1. Remove the condenser heads.
2. Clean and dry the tube sheets and the ends
of the tubes.
3. Start at the top and work your way down
the tube sheet.
4. Check both ends of each tube with a leak
Mark the tubes which show an indication of
leakage. If you cannot determine if the tube is
leaking internally or around the tube sheet joint,
plug the suspected tube with a cork or a similar
device and again check around the tube sheet
joint. Mark adjacent tubes, if necessary, to isolate
the suspected area.
5. To locate or isolate very small leaks in the
condenser tubes, hold the exploring tube at one
end of the condenser tube for about 10 seconds
to draw fresh air through the tube. Then drive
a cork in each end of the tube. Repeat this pro-
cedure with all the tubes in the condenser. Allow
the condenser tubes to remain plugged for 4 to
6 hours; then, remove the plugs one at a time and
check each tube for leakage. If a leaky tube is
detected, replace the plug immediately to reduce
the amount of refrigerant escaping. Make
appropriate repairs, or mark all leaky tubes for
The general procedure for retubing condensers
is outlined in Naval Ships Technical Manual
chapter 516. The procedures are given in the
applicable manufacturers technical manual when
a condenser of a specific type is being retubed.
An overall check for water-cooled condenser
performance may be used after, AND ONLY
AFTER, the condenser has been properly
purged. After the condition of the condensing sur-
face has been determined, prepare the system as
outlined in the procedure used to check for non-
condensable gases discussed earlier in the chapter.
Then proceed as follows:
1. While the compressor is in operation,
record the condensing temperature which cor-
responds to the pressure in the condenser.
2. Record the temperature of the water leav-
ing the condenser.
3. Subtract the temperature of the water leav-
ing the condenser from the condensing
temperature. (The temperature of the water leav-
ing the condenser should be several degrees below
the condensing temperature of pure R-12.)
4. If the difference between the temperature
of the water leaving the condenser and the con-
densing temperature is 5° to 10°F above the
temperature difference obtained when the con-
denser was in good condition and operating under
similar heat loads, and if this difference is not
caused by an overcharge of refrigerant or non-
condensable gases, clean the water side of the
When the thermostatic expansion valve is
operating properly, the temperature at the outlet
side of the valve is much lower than that at the
inlet side. If there is no such temperature dif-
ference when the system is in operation, the valve
seat is probably dirty and clogged with foreign
Once a valve is properly adjusted, further
adjustment should not be necessary. Any major
trouble can usually be traced to moisture or dirt
collecting at the valve seat and at the orifice.
TESTING AND ADJUSTMENT
Thermostatic expansion valves used in most
shipboard systems can be adjusted by means of
a gear and screw arrangement, (superheat to
Chapter 6REFRIGERATION AND AIR CONDITIONING