Rink

so equipped, the valve on the oil return line should also be closed. In addition, any primary refrigerant left in the crankcase must be purged, using proper safety procedures for that particular refrigerant, before the compressor can be opened. When considering compressor maintenance during the shut-down period, reference must be made to the manufacturer's recommendations. Usually, on a reciprocating compressor (screws may be different) the number of hours a compressor runs during any given season will determine the extent of necessary maintenance. When the compressor is opened for an internal inspection, all parts should be thoroughly checked and replaced where necessary and any additional wear investigated. Regardless of the need for replacement of internal compressor parts, the crankcase oil should be changed more frequently, ensuring that the interior of the crankcase is well flushed out prior to recharging with clean oil. A sample of the used oil from each compressor should be analyzed annually to help determine the wear on internal parts. Upon completion of any repair work, the compressor(s) should be closed up and filled to the correct level with oil that is compatible with the primary refrigerant. With respect to the secondary refrigerant equipment, the brine/glycol stop valves should remain open during the shut-down period to prevent hydraulic pressure damage due to expansion as the brine/glycol warms up. The rink floor piping, headers and brine/glycol lines should not be isolated from the brine/glycol expansion tank for the same reason. If using brine as the secondary refrigerant, the pump should be rotated at least once a month during shut-down to break up any calcium deposits that may damage pump seals. Bearings and valve stems should be greased. As well, bypass filters on the brine/glycol system should be cleaned or the filter replaced. Header pipes should be inspected for corrosion and loose hose clamps. The level of brine/glycol in the expansion tank should be checked and recorded. Once a year, a sample of brine/glycol should be taken and sent to a reputable lab for analysis. The lab should identify the strength and pH of the solution and, in addition, recommend any adjustments to the mixture and/or its treatment. Condenser inspection must not be forgotten during the shut-down period. On an evaporative condenser, coils should be checked for scale build-up, the condenser water tank drained and thoroughly flushed, and the spray nozzle system inspected for plugged or damaged nozzles and any problem nozzles replaced. In addition, all bearings and other moving parts require proper lubrication as stipulated by the manufacturer, including the condenser shaft. V belts should be inspected and replaced if necessary. Any filter used on the water circulating system should be cleaned or replaced, and all water valve stems should be greased. Water-cooled condensers must have the heads removed and the tubes cleaned, while air-cooled condensers should be power-washed and fins should be checked. With this work completed, the refrigeration system will be ready for start-up. march/april 2008 R IN K M A G AZ I N E 31 Refrigeration skid with reciprocating compressors. STAR PHOTO

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