This part of ISO 8573 specifies test methods for the sampling and quantitative analysis of oil aerosols and liquid oil that can typically be present in compressed air. Test methods for oil vapour are excluded from this part of ISO 8573 as they are covered by ISO 8573-5. Two different methods are described, method A and method B. Method B is subdivided into two parts to clearly distinguish between procedures for obtaining the quantity of oil for analysis.