Cleaning Suction StrainersWhen putting a new unit into operation, you shouldclean the suction strainers after a few hours of operation.Refrigerants have a solvent action and will loosen anyforeign matter in the system. This foreign matter willeventually reach the suction strainers. After a few daysof operation, the strainers will need another cleaning.Inspect them frequently during the first few weeks ofplant operation and clean as necessary.The suction strainers are located in the compressorhousing or in the suction piping. The procedure forcleaning the strainers is as follows:1. Pump down the compressor.2. Remove the strainer and inspect it for foreignmatter.3. Dip the strainer screen in an approved solventand allow it to dry.4. Replace the strainer and evacuate the air fromthe compressor.5. Test the housing for leaks by wiping up all oiland then using a halide leak detector.Maintenance PrecautionsSometimes a compressor cannot be pumped downand is damaged to the extent that it has to be opened forrepairs. If so, you should first close the suction anddischarge valves. Then allow all refrigerant in thecompressor to vent to the atmosphere through a gaugeline.When you must remove, replace, or repair internalparts of the compressor, observe the followingprecautions:1. Carefully disassemble and remove parts; notethe correct relative position so that errors will not bemade when you reassemble.2. Inspect all parts that become accessible.3. Make certain that all parts and surfaces are freeof dirt and moisture.4. Freely apply clean compressor oil to all bearingand rubbing surfaces of parts being replaced orreinstalled.5. If the compressor is not equipped with an oilpump, make certain that the oil dipper on the lowerconnecting rod is in the correct position for dipping oilwhen the unit is in operation.6. Position the ends of the piston rings so thatalternate joints are on the opposite side of the piston7. Take care not to score gasket surfaces.8. Replace all gaskets.9. Clean the crankcase and replace the oil.CONDENSERSThe compressor discharge line terminates at therefrigerant condenser. In shipboard installations, thesecondensers are usually of the multipass shell-and-tubetype, with water circulating through the tubes. The tubesare expanded into grooved holes in the tube sheet tomake a tight joint between the shell and the circulatingwater. Refrigerant vapor is admitted to the shell andcondenses on the outer surfaces of the tubes.Any air or noncondensable gases that mayaccidentally enter the refrigeration system will be drawnthrough the piping and eventually discharged into thecondenser with the refrigerant. The air ornoncondensable gases accumulated in the condenser arelighter than the refrigerant gas. They will rise to the topof the condenser when the plant is shut down. A purgevalve, for purging the refrigeration system (whennecessary), is installed at the top of the condenser or ata high point in the compressor discharge line.Cleaning Condenser TubesTo clean the condenser tubes properly, first drain thecooling water from the condenser. Then disconnect thewater connections and remove the condenser heads. Becareful not to damage the gaskets between the tube sheetand the waterside of the condenser heads. Inspect tubesas often as practical and clean them as necessary, usingan approved method. Use rubber plugs and an air lanceor a water lance to remove foreign deposits. You mustkeep the tube surfaces clear of particles of foreignmatter. However, you must not destroy the thinprotective coating on the inner surfaces of the tubes. Ifthe tubes become badly corroded, replace them.Replacement avoids the possibility of losing the chargeand admitting salt water to the system.Cleaning Air-Cooled CondensersAlthough the large plants are equipped withwater-cooled condensers, auxiliary units are commonlyprovided with air-cooled condensers. The use ofair-cooled condensers eliminates the necessity forcirculating water pumps and piping.5-6
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