This document specifies a method for the determination of the air saturated vapour pressure (ASVP) (total vapour pressure), exerted in vacuo, by volatile, low viscosity petroleum products, components, ethanol blends up to 85 % (V/V), and feedstocks containing air. A dry vapour pressure equivalent (DVPE) can be calculated from the air containing vapour pressure (ASVP) measurement. The conditions used in the test described in this document are a vapour-to-liquid ratio of 4:1 and a test temperature of 37,8 °C. The equipment is not wetted with water during the test, and the method described is therefore suitable for testing samples with or without oxygenates; no account is taken of dissolved water in the sample. The method described is suitable for testing air saturated samples with a DVPE between 15,5 kPa and 106,0 kPa; vapour pressures outside this range can be measured, but the precision has not been determined. This document is applicable to fuels containing oxygenated compounds up to the limits stated in the relevant Council Directive 85/536/EEC [10], and for ethanol-fuel blends up to 85 % (V/V) ethanol. NOTE For the purposes of this document, the terms “% (m/m)” and “% (V/V)” are used to represent the mass and volume fractions, respectively. WARNING - The use of this document can involve hazardous materials, operations and equipment. This document does not purport to address all of the safety problems associated with its use. It is the responsibility of users of this document to take appropriate measures to ensure the safety and health of personnel prior to application of the document, and to determine the applicability of any other restrictions for this purpose.