General Alarm Limits for Compressors

Compressors come in many configurations, and are subject to certain machine condition and lubricant condition requirements. Reciprocating compressor lubrication often involves drip feeding high viscosity lubricant to the cylinders, and use of a multi-grade motor oil in the crankcase. Cylinder lubrication is once-through, and there is no easy way to determine proper lubrication unless the cylinders are visually examined. The crankcase oil is subject to many of the same considerations as diesel and gasoline engines described earlier.

Rotary compressor lubrication analysis is much more important, since the circulating oil experiences much wider temperature variations, and also comes into contact with the gas being compressed. The oil is susceptible to oxidation at high temperatures, thereby increasing viscosity and acidity. High viscosity increases energy consumption, and the higher acidity promotes corrosion. The viscosity may also be subject to change based on the solubility of the gas being compressed.

Centrifugal compressors experience similar problems in the areas of acidity, viscosity and wear metals due to extended prolonged service intervals. the following table gives a rough idea on the alarm limits for compressors. These values are subject to change.