API MPMS 11.1.2-1980 (R1987)

The Objectives

The complete collection of the jointly issued API/ASTM-IP tables of which this volume is a part is
the result of close cooperation between the American Petroleum Institute (API), the Institute of
Petroleum (London) (IP), and the American Society for Testing and Materials (ASTM). The overall
objective of this effort was to meet the worldwide need for a uniform and authoritative
publication, based on the most accurate information available. This publication serves as a basis
for standardized calculations of measured quantities of petroleum fluids regardless of point of
origin, destination, or units of measure used by custom or statute. To meet the objective of
worldwide standardized measurement practices, the American National Standards Institute (ANSI) and
the British Standards Institute (BSI) have also been closely involved nationally, resulting in the
acceptance of the revised tables as an American National Standard and as a British Standard. In
addition, in their respective capacities as Secretariat of the International Organization for
Standardization TC/28 and of TC/28 SC3, ANSI and BSI have been instrumental in progressing the
revised tables towards their adoption as an international standard by the International
Organization for Standardization.

Historical Notes

The present collection supersedes all previous editions of the petroleum measurement Tables
ANSI/ASTM D 1250, IP200, and API Standard 2540. Action is being taken in ISO/TC 28 for the
corresponding tables listed in ISO R91 and the tables in the addendum to R91 to be superseded by
the present revised collection.

In view of the progress of metrication in countries formerly using the British system of weights
and measures, demand for the revision of the British edition does not justify the considerable work
involved. The present edition will therefore be withdrawn on the same date as the corresponding
metric and American editions are published and will not be replaced.

For the metric edition the new standard covers products with densities in the range 610.0 to 1076.0
kg/m³. The tables for densities below this range, covering liquefied petroleum gases, have not
been revised.

The original tables, which were developed in the late 1940s, were based on the 1916 data of Bearce
and Peffer (1916) and represent thirty years of evolution. The history of this evolution is
summarized by Hall et al. (1975).

Present Development

Downer and Inkley (1972) demonstrated that the original tables were not satisfactory
representations of many petroleum fluids of current importance. In 1974 the American Petroleum
Institute (API) and the United States National Bureau of Standards (NBS) initiated a research
program funded by the API which intended to provide the solid scientific base for the development
of more accurate, consequently more equitable, measurement tables. The result of this program was
precise density data on 349 different fluids representing a wide variety of refined products and
66.8 percent of the world crude production in 1974. The completion of this five-year, $500,000
project in March 1979 opened the way for modernizing the tables. Using the NBS density data and
taking advantage of publications of outstanding technical authorities, a Joint API-ASTM Physical
Properties Working Group produced this present collection of the Petroleum Measurement Tables. The
development and results of the work are described by Hankinson et al. (1979).

Conceptual Departure

A major conceptual departure from previous versions is inherent in the recognition of the present
and future position of computers in the petroleum industry. The actual Standard represented by this
volume and the companion volumes is neither the hardcopy printed tables nor the set of equations
used to represent the density data but is an explicit implementation procedure used to develop
computer subroutines. The standardization of an implementation procedure implies the
standardization of the set of mathematical expressions, including calculational sequence and
round-off procedures, used within the computer code. Absolute adherence to the outlined procedures
will ensure that all computers and computer codes of the future, meeting the stated specifications
and restrictions, will be able to produce identical results. Hence, the published implementation
procedures are the primary Standard, the distributed subroutines are the secondary standard, and
the published tables are produced for convenience.

Acknowledgments

The task of completing this project could not have been accomplished without many substantial
contributions by a considerable number of individuals and companies. It is impossible to single out
any specific individuals for special mention. However, included in the introductory material are
lists of the officers of the API's Committee on Petroleum Measurement (COPM), the officers of the
Joint API/ASTM Committee on Static Petroleum Measurement (COSM), the major contributors from the
Institute of Petroleum, and the members of the COSM Physical Properties Working Group.