ABSTRACT
This chapter reviews the history of previous work and the cooperative research activities that led to the preparation and availability of the new calibration standards that are traceable to the primary standards from the National Bureau of Standards. The Institute of Gas Technology has provided the American gas industry with natural gas standards of certified calorific value and specific gravity since 1965. The purification is accomplished by passing the gas over activated charcoal to remove hydrocarbons heavier than ethane, in order to improve gas stability. The processed gas, containing methane, ethane, nitrogen and carbon dioxide, is then adjusted to the desired calorific value or specific gravity before compression to 2000 psi into evacuated cylinders. Quality control is maintained by periodic gas analysis, and by regenerating the charcoal towers when propane breaks through. Gas analyzers that first determine the gas composition, then calculate the calorific value from the composition.
