Oil Charge & Oil pressure safety control

Oil Charge

Compressor leaving the copeland factory are charged with Sunusi-3G oil should be used without specific authorization from the copeland application ebgineering department. The napthenic base of the Suniso-3G oil has definite advarages over paraffinic oils because of less tendency to separate from the refrigerant at reduced temperatures.

Compressor are shipped with a generous supply of oil. However, the system may require additional oil depending on the refrigerant charge and system desing. After the unit stabilized at its normal operating conditions on the unitial run-in, additional oil should be added if necessary to maintain the oil level at the 3/4 full level of the sight glass in the compressor crankcase. The high oil level will provide a reserve for periods of erratic oil return.


Oil pressure safety control

A major percentage of all compressor failures are caused by lack of proper lubrication. Only ralely is the lack of lubrication actually due to a shortage of oil in the system or failure of the oiling system. More often the source of the lubrication failure may be refrigerant floodback, oil trapping in the coils, or excessive slugging on start up.

To prevent failures from all these causes, the copeland warranty requires that an approved manual reset type oil pressure safety control with a time delay of 120 seconds be used on all copelametic compressors having an oil pump. The control operates on the differential between oil pump pressure and crankcase pressure, and the time delay serves to avoid shut down during short fluctuations in oil pressure during start up. A non-adjustable control is strongly recommended, but if an adjustable type control is used, it must be set to cyt aut at a net differential pressure of 9 psig. Oil pressure safety controls are available with alarm circuits which are energized should the oil pressure safety control open the compressor control circuit.