addressing uncertainty in oil and natural gas industry greenhouse

In this method air is mixed with the gaseous fuel to be tested. The mixture is burned and the air-fuel ratio is
adjusted so that essentially a stoichiometric proportion of air is present. The adjustment is made so that the
air-fuel ratio is in a constant proportion to the stoichiometric ratio that is a relative measure of the heating
value. To set this ratio, a characteristic property of the burned gas is measured, such as temperature or
oxygen concentration.
This test method provides an accurate and reliable procedure to measure the total heating value of a fuel gas,
on a continuous basis, which is used for regulatory compliance, custody transfer, and process control. Some
instruments which conform to the requirements set forth in this test method can have response times on the
order of 1 min or less and can be used for on-line measurement and control. The method is sensitive to the
presence of oxygen and unsaturated hydrocarbons. For components not listed and composition ranges that
fall outside those in Table 7, such as in process or refinery fuel gases, modifications in the method may be
required to obtain correct results.
In testing the precision and accuracy of this method, repeatability within a laboratory was shown to be 0.76
Btu/scf, with the corresponding 95% confidence of the repeatability interval being 2.1 Btu/scf.
Reproducibility between laboratories was determined to be 1.67 Btu/scf with the corresponding 95%
confidence reproducibility interval 5.1 Btu/scf. The average bias of all measurements agreed with the
average reference value to within 0.1%.
b. ASTM D1826 – 94, Standard Test Method for Calorific (Heating) Value of Gases in Natural Gas Range
by Continuous Recording Calorimeter, (Reapproved 2003)
This test method covers the determination – with the continuous recording calorimeter – of the total calorific
(heating) value of fuel gas produced or sold in the natural gas range from 900 to 1200 Btu/scf. The heating
value is determined by imparting the heat obtained from the combustion of the test gas to a stream of air and
measuring the rise of the air temperature. The streams of test gas and heat absorbing air are maintained in
fixed volumetric proportion to each other by metering devices similar to the ordinary wet test meters geared
together and driven from a common electric motor. The meters are mounted in a tank of water, the level of
which is maintained and the temperature of which determines the temperature of the entering gas and air.
The experimental set-up is such that the temperature rise produced in the heat-absorbing air is directly
proportional to the heating value of the gas. Since all the heat from the combustion of the test gas sample,
including the latent heat of vaporization of the water vapor formed in the combustion, is imparted to the
heat-absorbing air, the calorimeter makes a direct determination of total heating value. The temperature rise
is measured by nickel resistance thermometers and is translated into Btu/scf.
This test method provides an accurate and reliable method to measure the total calorific value of a fuel gas,
on a continuous basis, which is used for regulatory compliance, custody transfer, and process control. As
far as precision, the calorimeters tested were standardized with methane weekly, and a rigid control was
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