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Informational Letter IL 81-21
| TO: |
All Oil and Gas Operators,
Canadian Petroleum Association,
Independent Petroleum Association of Canada,
and Certain Others |
STANDARD UNIT OF MEASUREMENT FOR ETHANE
In Informational Letter IL 79-4, the Board indicated that since Sector 4.02 (Petroleum and Natural Gas Industry and Services) of Metric Commission of Canada had adopted the kilogram mass unit as the standard unit of measurement for ethane, the Board would require all such data in kilograms. However, much of the industry and government are using the cubic metre of liquid as the unit of measurement for ethane, mainly because the cubic metre is used as the standard unit of measurement for propane, butanes, pentanes plus, and most other hydrocarbons. Consequently, for simplicity and in order to maintain consistency with others, the Board has decided to adopt the cubic metre of liquid as the standard unit of measurement for ethane.
While the Board has historically used conversion factors for pure ethane, the National Energy Board and others have adopted conversion factors derived on the basis of an average industrial specification ethane. Since the factors differ only slightly and having regard for measurement inaccuracies, the Board has decided to adopt conversion factors having an accuracy of only three significant figures which it will apply to both pure and industrial specification ethane.
The Board has adopted the following frequently-used conversion factors which yield cubic metres of ethane in the liquid phase at equilibrium pressure and 15oC:
| 1 barrel (equilibrium pressure and 60oF) |
= 0.158 m3 |
| 1 imperial gallon (equilibrium pressure and 60oF) |
= 4.52 x 10-3 m3 |
| 1 cubic foot of ethane gas (14.65 psia and 60oF) |
= 100 x 10-6 m3 |
| 1 kilogram (weight in vacuum) |
= 2.79 x 10-3 m3 |
| 1 cubic metre of ethane gas (101.325 kilopascals and 15o C) |
= 3.55 x 10-3 m3 |
The Board has also adopted 18.5 x 109 joules as the higher heating value of one cubic metre of ethane liquid at equilibrium pressure and 15oC.
While these factors are adequate for purposes of converting historical data, the Board expects that for custody transfer operations, detailed engineering calculations or other work requiring a higher level of accuracy, factors may have to be developed which more accurately reflect specific product composition.
Questions respecting the above matters may be directed to Mr. H. G. Halladay of the Board's Gas Department at 261-8291.
Dated at Calgary, Alberta on the 15th day of July 1981.
[signed by]
G.J. DeSorcy
Vice Chairman
