Although the large plants are equipped with water-cooled condensers, the auxiliary units are commonly provided with air-cooled condensers. The use of air-cooled condensers eliminates the necessity for circulating water pumps and piping. The exterior surface of the tubes and fins on a condenser should be kept free of dirt and any matter that might obstruct heat flow and air circulation. Brush the finned surface clean with a stiff bristle brush as often as necessary. Use low pressure air to remove dirt in hard to reach places on the condenser. When installations are exposed to salt spray and rain through open doors or hatches, take care to minimize corrosion of the exterior surfaces.

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 be tested.

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 following manner:

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 detector.

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 procedure 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 later repairs.

RETUBING CONDENSERS

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.