TESTING FOR LEAKSTo prevent serious loss of refrigerant throughleaky condenser tubes, test the condenser forleakage every week. Any condenser that has notbeen in use for the preceding 12 hours should alsobe tested.To test for leaky condenser tubes, drain thewater side of the condenser and let stand for 12hours, then insert the exploring tube of the leakdetector through one of the drain plug openings.If this test indicates that R-12 gas is present, youneed to detect the exact location of the leak in thefollowing manner:1. Remove the condenser heads.2. Clean and dry the tube sheets and the endsof the tubes.3. Start at the top and work your way downthe tube sheet.4. Check both ends of each tube with a leakdetector.Mark the tubes which show an indication ofleakage. If you cannot determine if the tube isleaking internally or around the tube sheet joint,plug the suspected tube with a cork or a similardevice and again check around the tube sheetjoint. Mark adjacent tubes, if necessary, to isolatethe suspected area.5. To locate or isolate very small leaks in thecondenser tubes, hold the exploring tube at oneend of the condenser tube for about 10 secondsto draw fresh air through the tube. Then drivea cork in each end of the tube. Repeat this pro-cedure with all the tubes in the condenser. Allowthe condenser tubes to remain plugged for 4 to6 hours; then, remove the plugs one at a time andcheck each tube for leakage. If a leaky tube isdetected, replace the plug immediately to reducethe amount of refrigerant escaping. Makeappropriate repairs, or mark all leaky tubes forlater repairs.RETUBING CONDENSERSThe general procedure for retubing condensersis outlined in Naval Ships’ Technical Manualchapter 516. The procedures are given in theapplicable manufacturer’s technical manual whena condenser of a specific type is being retubed.CHECKING CONDENSERPERFORMANCEAn overall check for water-cooled condenserperformance may be used after, AND ONLYAFTER, the condenser has been properlypurged. After the condition of the condensing sur-face has been determined, prepare the system asoutlined 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 condensingtemperature. (The temperature of the water leav-ing the condenser should be several degrees belowthe condensing temperature of pure R-12.)4. If the difference between the temperatureof the water leaving the condenser and the con-densing temperature is 5° to 10°F above thetemperature difference obtained when the con-denser was in good condition and operating undersimilar heat loads, and if this difference is notcaused by an overcharge of refrigerant or non-condensable gases, clean the water side of thecondenser.THERMOSTATIC EXPANSIONVALVESWhen the thermostatic expansion valve isoperating properly, the temperature at the outletside of the valve is much lower than that at theinlet side. If there is no such temperature dif-ference when the system is in operation, the valveseat is probably dirty and clogged with foreignmatter.Once a valve is properly adjusted, furtheradjustment should not be necessary. Any majortrouble can usually be traced to moisture or dirtcollecting at the valve seat and at the orifice.TESTING AND ADJUSTMENTThermostatic expansion valves used in mostshipboard systems can be adjusted by means ofa gear and screw arrangement, (superheat toChapter 6—REFRIGERATION AND AIR CONDITIONING6-9
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