This standard specifies a method for the determination of the total pressure exerted in vacuo, by aircontaining crude oil at 37,8 °C and with a vapour to liquid ratio of 4:1. The samples of crude oil used to obtain the precision statement for this method had viscosities in the range 3,5 mm2/s to 1 2,5 mm2/s at 20 °C. No account is made of dissolved water in the sample. A Reid equivalent vapour pressure can be calculated from the ASVP measurement.Eralytics