The fuel consumption of oil-injected screw air compressors is typically expressed in parts per million (ppm).

The concept of ppm: It represents one part in a million by mass. For example, 5 ppm oil content indicates that the mass of oil inhaled in 1 m³ of air is equal to one part in a million of its mass.

In other words, if the oil content is 5 ppm, it means that for every 1 million parts of air, there are 5 parts of oil by mass. This measurement is used to quantify the oil content in the compressed air produced by the oil-injected screw air compressor, indicating the level of oil carryover or oil contamination in the compressed air output. Lower ppm values indicate better oil separation and higher air quality.