This European Standard specifies a method for the determination of the absolute vapour pressure of volatile crude oil and volatile non-viscous petroleum products, with vapour pressures below 180 kPa.
This method is applicable to fuels containing oxygenated compounds up to the limits stated in Annex A, column A of this standard. The method is also applicable to fuels containing up to 2,8 〓 m/m total oxygen, if due to ethers only.
NOTE 1:
For higher oxygenate contents national standards may be applied until
a European Standard has been developed.
NOTE 2:
Because the external atmospheric pressure is counteracted by the atmospheric pressure initially present in the air chamber, the "Reid vapour pressure" is approximately the absolute vapour pressure of the material at 37,8°C in kilopascals (bars). The "Reid vapour pressure" differs from the true vapour pressure of the sample owing to slight vaporisation and the presence of water vapour and air in the confined space.