4. Close the discharge gage line and open thedischarge line stop valve.5. Remove all oil from the exterior of thecompressor, and test the compressor joints forleakage, using the halide leak detector.CLEANING SUCTION STRAINERSWhen putting a new unit into operation, thesuction strainers should be cleaned after a fewhours of operation. Refrigerants have a solventaction and will loosen any foreign matter in thesystem. This foreign matter will eventually reachthe suction strainers and after a few days of opera-tion, the strainers will need cleaning. Strainersshould be inspected frequently during the first fewweeks of plant operation, and then cleaned asfound necessary.The suction strainers are located either in thecompressor housing or in the suction piping. Theprocedure for cleaning a strainer is as follows:1.2.3.4.5.6.Pump down the compressor.Slowly bleed pressure from unit.Remove the strainer and inspect it forforeign matter.Clean the strainer screen by dipping it inan approved solvent and then allow it todry.Replace the strainer and evacuate the airfrom the compressor.Test the housing for leaks by wiping up alloil and then using a halide leak detector.CONDENSERSThe compressor discharge line terminates atthe refrigerant condenser. In shipboard R-12installations, these condensers are usually of themultipass shell-and-tube type, with water cir-culating through the tubes. The tubes are ex-panded into grooved holes in the tube sheet soas to make an absolutely tight joint between theshell and the circulating water. Refrigerant vaporis admitted to the shell, and condenses on theouter surfaces of the tubes.Any air or noncondensable gases which mayaccidentally enter the refrigeration system isdrawn through the piping and eventually dis-charged into the condenser with the R-12 gas. Theair or noncondensable gases accumulated in thecondenser are lighter than the refrigerant gas andrise to the top of the condenser when the plantis shut down. A purge valve, for purging therefrigeration system (when necessary), is installedeither at the top of the condenser, or at a highpoint in the compressor discharge line.CLEANING CONDENSER TUBESIn order to clean the condenser tubesproperly, it is necessary first to drain the coolingwater from the condenser and then disconnect thewater connections and remove the condenserheads. When you remove the condenser heads,be careful not to damage the gaskets between thetube sheet and the water side of the condenserheads. Tubes should be inspected as often as prac-ticable and be cleaned when necessary, by usingany approved method. Use rubber plugs and anair or water lance when it is necessary to removeforeign deposits. Although it is essential that thetube surfaces be kept clear of particles of foreignmatter, care must be taken not to destroy the thinprotective coating on the inner surfaces of thetubes. When the tubes become badly corroded,they should be replaced in order to avoid thepossibility of losing the R-12 charge and admit-ting salt water into the R-12 system.CLEANING AIR-COOLEDCONDENSERSAlthough the large plants are equipped withwater-cooled condensers, the auxiliary units arecommonly provided with air-cooled condensers.The use of air-cooled condensers eliminates thenecessity for circulating water pumps and piping.The exterior surface of the tubes and fins ona condenser should be kept free of dirt and anymatter that might obstruct heat flow and air cir-culation. Brush the finned surface clean with astiff bristle brush as often as necessary. Use lowpressure air to remove dirt in hard to reach placeson the condenser. When installations are exposedto salt spray and rain through open doors orhatches, take care to minimize corrosion of theexterior surfaces.ENGINEMAN 1 & C6-8
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