(a) Allowable concentration. The gas distributed by each company shall contain not more than five grains of ammonia per 100 cubic feet of gas volume measured at a temperature of 60 degrees Fahrenheit and an absolute pressure of 30 inches of mercury column.
(b) Equipment, testing procedure and required tests. In each instance of evidence of or doubt or difference of opinion regarding the presence of ammonia in the distributed gas, each company may be required to make suitable tests therefor with suitable equipment and a suitable testing procedure at its testing stations required by subdivisions (a) through (d) of section 229.50 of this Part as directed by this commission.