EN ISO 8973:1999

Liquefied petroleum gases - Calculation method for density and vapour pressure (ISO 8973:1997)

Migrated from Progress Sheet (TC Comment) (2000-07-10): Decision of BT to submit this ISO document to UAP procedure. ++ AWAITING FOR ISO RESULT

Gaz de pétrole liquéfiés - Méthode de calcul de masse volumique et de la pression de vapeur (ISO 8973:1997)

Utekočinjeni naftni plini – Računska metoda za gostoto in parni tlak (ISO 8973:1997)

General Information

• Status: Published
• Publication Date: 23-Mar-1999
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: CEN/TC 19 - Petroleum products, lubricants and related products
• Drafting Committee: CEN/TC 19 - Petroleum products, lubricants and related products
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 20-Mar-2013
• Completion Date: 20-Mar-2013
• Ref Project: SIST EN ISO 8973:1999 - Liquefied petroleum gases - Calculation method for density and vapour pressure (ISO 8973:1997)

Relations

• Amended By: EN ISO 8973:1999/A1:2020 - Liquefied petroleum gases - Calculation method for density and vapour pressure - Amendment 1 (ISO 8973:1997/Amd 1:2020)
• Effective Date: 31-Oct-2018

Overview

EN ISO 8973:1999 (ISO 8973:1997) specifies a simplified, composition‑based calculation method for determining the liquid density and vapour pressure of liquefied petroleum gas (LPG). The method uses LPG compositional data (molar fractions obtained by gas chromatography) together with empirical density and vapour‑pressure factors for individual hydrocarbon components (provided in Annex A). It is intended for product quality specification and laboratory reporting - not for custody transfer quantity measurement.

Keywords: EN ISO 8973, ISO 8973, liquefied petroleum gas, LPG density calculation, vapour pressure, gas chromatography, product quality specification.

Key topics and requirements

• Scope and purpose
  • Simplified calculation method based on composition and component factors.
  • Not suitable for custody transfer measurement (see ISO 6578).
• Input data
  • Molar composition determined by gas chromatography in accordance with ISO 7941.
  • Use relative molecular masses and the density factors (kg/m3 at 15 °C) and vapour pressure factors (kPa at 37.8 °C, 40 °C, 50 °C or 70 °C) listed in Annex A.
• Calculation steps
  • Convert mole fractions to mass fractions using relative molecular masses.
  • Calculate liquid density at 15 °C as a weighted combination of component density factors.
  • Calculate component partial vapour pressures as mole fraction × component vapour‑pressure factor and sum to obtain the mixture absolute vapour pressure.
  • Convert to gauge vapour pressure by subtracting local atmospheric pressure (101.325 kPa).
• Reporting and precision
  • Report density to the nearest 0.1 kg/m3 and vapour pressure to the nearest 1 kPa.
  • Precision depends on gas chromatography accuracy and the empirical factor values.
• Annexes
  • Annex A (normative): table of factors for common LPG components.
  • Annex B (informative): bibliography and related measurement methods.

Applications and who uses it

• Quality control laboratories analyzing LPG batches for product specifications.
• LPG producers and distributors when defining or verifying product quality parameters.
• Standards committees and spec writers using a standardized calculation for contractual or regulatory specifications.
• Engineers and safety assessors estimating vapour pressures for storage, handling, venting and safety assessments (note: for custody transfer and custody‑related quantity measurement use ISO 6578).
• Useful for integration into laboratory information systems, reporting templates, and technical datasheets where a consistent, reproducible calculation method is required.

Related standards

• ISO 7941 - Analysis by gas chromatography for commercial propane and butane (molar composition).
• ISO 6578 - Refrigerated hydrocarbon liquids: static measurement (custody transfer procedures).
• ISO 3993, ISO 4256 - Methods referenced for density and vapour pressure determination (background bibliography).

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-1999
8WHNRþLQMHQLQDIWQLSOLQL±5DþXQVNDPHWRGD]DJRVWRWRLQSDUQLWODN,62

Liquefied petroleum gases - Calculation method for density and vapour pressure (ISO
8973:1997)
Gaz de pétrole liquéfiés - Méthode de calcul de masse volumique et de la pression de
vapeur (ISO 8973:1997)
Ta slovenski standard je istoveten z: EN ISO 8973:1999
ICS:
75.160.30 Plinska goriva Gaseous fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATI
STANDARD
First edition
1997-07-I 5
Liquefied petroleum gases - Calculation
method for density and vapour pressure
M&hode de calcul de la masse volumique et de
Gaz de p&role liqubfibs -
la pression de vapeur
Reference number
IS0 8973: 1997(E)
IS0 8973:1997(E)
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for which
a technical committee has been established has the right to be represented
on that committee. International organizations, governmental and non-
governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 8973 was prepared by Technical Committee
ISORC 28, Petroleum products and lubricants.
Annex A forms an integral part of this International Standard. Annex B is for
information only.
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
x.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
IS0 8973: 1997(E)
INTERNATIONAL STANDARD @ Iso
Calculation method for density and
Liquefied petroleum gases -
vapour pressure
1 Scope
This International Standard describes a simplified method for the calculation of density and vapour pressure of
liquefied petroleum gases (LPG) based on compositional data and density and vapour pressure factors for
individual LPG components. A list of factors is provided in this International Standard. This method is intended for
application in specifications of product quality and is not intended for application to quantity measurement in custody
transfer (see IS0 6578).
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 6578: 1991, Refrigerated hydrocarbon liquids - Static measurement - Calculation procedure.
- Analysis by gas chromatography.
IS0 7941: 1988, Commercial propane and butane
3 Definitions
For the purpose of this International Standard the following definitions apply.
3.1 liquefied petroleum gas (LPG): Hydrocarbon gas that can be stored and/or handled in the liquid phase under
moderate conditions of pressure and at ambient temperature. lt consists essentially of C3 and C4 alkanes or
alkenes, or a mixture of these, contains generally less than 5 % by liquid volume of material of higher carbon
number, and has a gauge vapour pressure not exceeding approximately 1 600 kPa at 40 OC.
3.2 density factor: Density, expressed in kilograms per cubic metre, of a component in the liquid phase under its
own vapour pressure at a temperature of 15 OC.
3.3 vapour pressure: Vapour pressure, expressed in kilopascals on an absolute basis, i.e. the gauge pressure
plus local ambient pressure.
3.4 vapour pressure factor: Absolute vapour pressure, expressed in kilopascals, of a component of the liquid at
temperature of 37,8 “C, 40 “C, 50 “C or 70 OC.
...