1.1 Introduction concerning duties of compressorsThe following guidelines are given to help interested parties in differentiating between-light duty-medium duty-heavy duty(see also ISO 5388)1.2 Reciprocating oil-lubricated and rotary drip-feed air compressorsWhether the duty of reciprocating and rotary drip feed compressors is to be classified as light, medium, orheavy depends on many parameters, for examplea) the compressor design, ie, type of cooling, number of stages, valve velocities, oil retention time, etcb) ambient conditions, ie, intake "air" temperature, coolant temperature, presence of catalytic dust or gases, etc;c) operating conditions, ie, continuous or intermittent service, layout of the pressure system, maintenance, oil change intervals, etcThe ultimate criterion is satisfactory, reliable air compressor operation with the prevention of excessive oilretention or the formation of coke deposits in the hot discharge air system1.3 Rotaryoil-flooded air compressorsWhether the duty of rotary oil-flooded air compressors is to be classified as light, medium, or heavydepends on many parameters, for examplea) the compressor design, ie, air discharge pressure and pressure ratio, number of stages, oil recirculation rate, oil separating system, etc;b) ambient conditions, ie, intake air temperature and humidity, presence of contaminants (dust or gases), etc;c) operating conditions, ie, continuous or intermittent service, maintenance, oil change intervals, discharge temperature, etcNOTE--Conditions such as air humidity or Iow circulating air volume may recommend an oil for heavier duty