The mass of oil (including oil droplets, suspended particles, and oil vapor) contained in a unit volume of compressed air, converted to atmospheric conditions of 0.1 MPa absolute pressure, 20°C temperature, and 65% relative humidity. Unit: mg/m³ (absolute value).
PPM is a symbol representing the content of trace substances in a mixture, indicating the number of parts per million or parts per million (parts by weight PPMw and parts by volume PPMv). (Refers to ratios) Usually, PPM refers to the weight ratio. (One part per million of 1 kg is a milligram)
1 PPMw = 1.2 mg/m³ (PA = 0.1 MPa, t = 20°C, φ = 65%)
Generally, the oil content in the exhaust gas of oil-injected screw air compressors is below 5 PPM, but the exhaust gas of centrifugal and oil-free compressors is oil-free. Considering the oil particles naturally present in the air, reaching 100% oil content is impossible.
