I. The mass of oil (including oil droplets, suspended particles, oil vapor) contained in compressed air per unit volume is converted to an absolute pressure of 0.1 MPa, a temperature of 20 ° C and a relative humidity of 65% under atmospheric conditions. Unit: mg/m3 (refers to the absolute value)
II. PPM A symbol indicating the content of a trace substance in a mixture, and means a part per million or parts per million (part weight ratio PPMw and volume ratio PPMv) (refer to a ratio).
Usually we call PPM as the weight ratio. (One millionth of a kilogram is 1 milligram)
1PPMw=1.2mg/m3 (PA=0.1MPa, t=20°C, φ=65%)
Generally, the oil content of the air-injection screw air compressor is less than 5 PPM, but the centrifuge and the oil-free exhaust gas are oil-free. It is impossible to achieve 100% in consideration of the oil particles originally contained in the air.