(a)  The utility may not be required to determine the heating value of the gas sold if its gas supply is purchased from pipeline companies which determine the heating value in a manner acceptable to the Commission; however, if the utility sells any of its gas on a BTU basis, it shall determine the heating value and install a calorimeter in the manner provided in Subsection (b)(1), (2), (3) of this rule.

(b)  The utility, if required to determine heating value under subsection (a) of this rule, shall provide and maintain a calorimeter of a type acceptable to the Commission for the regular determination of the heating value of the gas sold.

(1)           The calorimetric equipment shall be installed in a suitably located testing station acceptable to the Commission and subject to its inspection.

(2)           The accuracy of all calorimeters, as well as the method of making heating value tests, shall be acceptable to the Commission. Recording calorimeters shall be tested with a standard gas at least once each month.

(3)           Heating value test records shall be preserved for at least 3 years.