ISO 8973:1997 pdf download – Liquefied petroleum gases–Calculation method for density and vapour pressure.
Thea International Standard d..crlbes a simpIied method for the calculation of density and vapour pressure of liquefied petroleum gases (LPG) based on compo&tlonai data and density arid vapour pressure factors for individual LPG components. A list of factors e provided in this International Standard, This method Ii Itended for appllcalrnn In specdications of product quality and e not intended for application to quantity measurement In custody transfer (see ISO 6578).
2 Normative references
The following standards contain provisions which, through reference In this lext. constitute provisions of this International Standard. At the trne of publication, the editions Indicated were valid. Al standards are subject to revision, and parties to agreements based on this International Standard are encouraged to Investigate the possibdity of applying the most recent editions of the standards Indicated below. Mentors of IEC and ISO maintain regeteis of curentty valid International Standards.
ISO 6578:1991, Rehgerated flydcocaibon liquids — Static measuremenl — Caicufetion procedure. 1S07941:1998, Commernisl propane and butane — Analysis by gas chrom.tograpiy.
3 DefinItions
For the purpose of this International Standard the following definitions apply.
3.1 lfqudi.d petroleum gas (LPG): Hydrocarbon gas that can be stored and/or handled in the liquid phase wid.r moderate conditions of pressure and at ambient temperature. ft consists essentially of C and C4 alkanes or alkenes. or a rvvxture of those, contains generally less than 5 % by liquid volume of material of higher carbon number, and has a gauge vapour proasur. not exceeding approximately 1 600 liPs sf40 C.
32 d.nslty factor: Density, expressed in kilograms per cubic metre, of a ooinponent in the lequid phase under *i own vapour pressure ata temperature of 15 C.
3.3 vapour pr.ssur.: Vapour pressure, expressed In lolopascals on an absolute basis, i.e. the gauge pressure plus kxai ambient pressure
3.4 vapour pressure factor: Absolute vapour pressure, expressed in kilopascais. of a component of the liquid at ternperatureol37,8C. 40C,50Co7OC.
The molar composition of the LPG is determined by gas chromatography in accordance with ISO 7941.Thisanalysis is used to calculate the liquid density and vapour pressure by using, for each component, the liquid densityand vapour pressure factors provided in this International Standard.
5 Procedure
Determine the molar composition in accordance with ISO 7941.
6 Calculation
6.1 Use the LPG component relative molecular mass,density and pressure factors given in table A.1 in theequations shown below.
6.2.1 Calculate the mass fraction,w, of each component of the mixture as follows:
7Expression of results
Report the calculated density to the nearest 0,1 kg/m3 and the calculated vapour pressure to the nearest 1 kPa.
The precision of this method is dependent on the precision of the original gas chromatography determination of theLPG composition and the accuracy of the factors which are entered into the calculation.
9Test report
The test report shall contain at least the following information:a)reference to this International Standard;
b)the type and complete identification of the product tested;c)the result of the test (see clause 7y;
any deviation, by agreement or otherwise, from the procedure specified;e)the date of the test.