(a) Determination for metering purposes. Where a company is required by the provisions of subdivision (a) of section 229.20 herein to provide any of its testing stations required herein by subdivisions (a) through (d) of section 229.50 with a recording gravitometer for the purpose of determining the specific gravity of the distributed gas in a manner adequate for orifice and other types of velocity metering, said company shall continuously record the specific gravity of the distributed gas therewith. Each said recording gravitometer shall be calibrated once each calendar month at intervals of not more than 35 days and the results recorded. Each said recording gravitometer shall be adjusted if it is determined to be in error.
(b) Automatic determination. Where the tests set forth in subdivision (a) are not required, the company shall determine the specific gravity of the distributed gas either in compliance with subdivision (c) herein or continuously determine the specific gravity of the distributed gas with automatic specific gravity equipment at the testing stations required herein by subdivisions (a) through (d) of section 229.50 in compliance with this rule. Where the automatic specific gravity equipment is of an indicating type, the specific gravity of the distributed gas shall be read and recorded daily therefrom. In all instances, automatic specific gravity equipment shall be calibrated once each alternate calendar month at intervals of not more than 70 days and the results recorded.
(c) Manual determination. Unless tests are made in conformity with subdivisions (a) or (b) herein, each company shall determine and record the specific gravity of the distributed gas with manual specific gravity equipment at the testing stations required herein by subdivisions (a) through (d) of section 229.50 except that at a testing station testing gas obtained from a stand-by source, said tests need not be made during any day that gas be obtained from said stand-by source for a total of less than one hour.