<p>This International Standard specifies a method for the determination of the vapour pressure of liquid petroleum</p>
<p>products consisting of essentially or wholly of hydrocarbon components, or containing oxygenated hydrocarbons of</p>
<p>specific types and at specified maximum concentrations. The method does not apply outside these concentration</p>
<p>levels, nor to any blends containing methanol or other oxygenated hydrocarbons not covered in note 1.</p>
<p>NOTE 1 The maximum concentration of ethers containing 5 or more carbon atoms is 15 % (<i>V</i>/<i>V</i>), and for ethanol is 10 %</p>
<p>(<i>V</i>/<i>V</i>). For higher alcohols, the maximum concentration is 7 % (<i>V</i>/<i>V</i>).</p>
<p>NOTE 2 For the purposes of this International Standard, the term "%(V/V)" is used to represent the volume fraction of a</p>
<p>material.</p>
<p>For petroleum products containing methanol, or other oxygenated hydrocarbons outside the scope of note 1, a dry</p>
<p>vapour-pressure test method should be used. For liquefied petroleum gases, ISO 4256 should be used. The test</p>
<p>method may be applied to volatile crude petroleum with a vapour pressure exceeding 10 kPa, although the</p>
<p>precision has not been evaluated.</p>
<p>Four procedures are described in this International Standard. Procedures A and B are alternative apparatus</p>
<p>configurations for products with a Reid vapour pressure up to 180 kPa, Procedure C is applied to liquid products</p>
<p>with a Reid vapour pressure above 180 kPa, and Procedure D applies to aviation gasolines with a Reid vapour</p>
<p>pressure of approximately 50 kPa.</p>
<p>Vapour pressure is an important physical property of volatile liquids, and has critical performance implications for</p>
<p>automotive and aviation gasolines. Vapour pressure is also one of the properties affecting atmospheric evaporation,</p>
<p>and is therefore increasingly used in regulations relating to emissions and air quality control. Vapour pressure is</p>
<p>also a critical property limiting the performance and safety of operation of equipment during transfer operations.</p>
<p>NOTE Because the external atmospheric pressure is counteracted by the atmospheric pressure initially in the vapour</p>
<p>chamber, the Reid vapour pressure is approximately the "absolute" vapour pressure at 37,8 °C. The Reid vapour pressure</p>
<p>differs from the true vapour pressure of the sample owing to slight vaporization of the sample and the pressure of water vapour</p>
<p>and air in the confined space.</p>
Registration number (WIID)
8082
Scope
<p>This International Standard specifies a method for the determination of the vapour pressure of liquid petroleum</p>
<p>products consisting of essentially or wholly of hydrocarbon components, or containing oxygenated hydrocarbons of</p>
<p>specific types and at specified maximum concentrations. The method does not apply outside these concentration</p>
<p>levels, nor to any blends containing methanol or other oxygenated hydrocarbons not covered in note 1.</p>
<p>NOTE 1 The maximum concentration of ethers containing 5 or more carbon atoms is 15 % (<i>V</i>/<i>V</i>), and for ethanol is 10 %</p>
<p>(<i>V</i>/<i>V</i>). For higher alcohols, the maximum concentration is 7 % (<i>V</i>/<i>V</i>).</p>
<p>NOTE 2 For the purposes of this International Standard, the term "%(V/V)" is used to represent the volume fraction of a</p>
<p>material.</p>
<p>For petroleum products containing methanol, or other oxygenated hydrocarbons outside the scope of note 1, a dry</p>
<p>vapour-pressure test method should be used. For liquefied petroleum gases, ISO 4256 should be used. The test</p>
<p>method may be applied to volatile crude petroleum with a vapour pressure exceeding 10 kPa, although the</p>
<p>precision has not been evaluated.</p>
<p>Four procedures are described in this International Standard. Procedures A and B are alternative apparatus</p>
<p>configurations for products with a Reid vapour pressure up to 180 kPa, Procedure C is applied to liquid products</p>
<p>with a Reid vapour pressure above 180 kPa, and Procedure D applies to aviation gasolines with a Reid vapour</p>
<p>pressure of approximately 50 kPa.</p>
<p>Vapour pressure is an important physical property of volatile liquids, and has critical performance implications for</p>
<p>automotive and aviation gasolines. Vapour pressure is also one of the properties affecting atmospheric evaporation,</p>
<p>and is therefore increasingly used in regulations relating to emissions and air quality control. Vapour pressure is</p>
<p>also a critical property limiting the performance and safety of operation of equipment during transfer operations.</p>
<p>NOTE Because the external atmospheric pressure is counteracted by the atmospheric pressure initially in the vapour</p>
<p>chamber, the Reid vapour pressure is approximately the "absolute" vapour pressure at 37,8 °C. The Reid vapour pressure</p>
<p>differs from the true vapour pressure of the sample owing to slight vaporization of the sample and the pressure of water vapour</p>
<p>and air in the confined space.</p>
