§ 59.15. Measurement of gas at higher than standard service pressure.
(a) Pressure-recording equipment. If gas is measured to customers through displacement meters at a pressure greater than standard service pressure, the meters shall be equipped with reliable pressure-volume recording gauges or other devices for accurately determining the quantity of gas which has passed through the meter in accordance with contract or tariff provisions.
(b) Determination of multiplier. In computing the volume of gas at a given pressure base from a pressure-volume chart, the multiplier shall be obtained by the weighted average method, which consists of determining the average pressure for each indicated unit volume on the chart.
(c) Fixed pressure factor measurement. If the gas metering pressure can be maintained at a constant level so that it will not vary by more than plus or minus 1.0% of the absolute metering pressure, the quantity of gas corrected for pressure for billing purposes may be determined by multiplying the uncorrected volume by the factor of Metering Pressure Plus Atmospheric Pressure Divided by Base Pressure or by a special index with gearing to perform this calculation. The special index shall meet the specifications of ANSI Standard B109.1, § 6.2 (1986) or ANSI Standard B109.1, § 6.9 (1986). The ability of the regulator to maintain the constant pressure shall be verified at or prior to installation. Verification will be established by the use of a verified pressure-indicating gauge (accuracy: ANSI B40.1 Grade 3A), or a pressure-recording gauge, at both high and low flow conditions. When customer load is measured with a meter with a rated capacity of 1,500 cubic feet per hour or less, with metering pressure less than 3 psig, the performance of the regulator shall be verified in accordance with the test schedule of the downstream meter, established under § 59.21 (relating to meter tests). When customer load is measured with a meter with a capacity of over 1,500 cubic feet per hour or metering pressure of 3 psig or more, the performance of the regulator shall be verified at least every 5 years, except that those installed before January 1, 1990, shall be verified at least every 2 years.
(d) Determination of static and differential pressure. In computing the volume of gas at a given pressure base from an orifice meter chart, the average static pressure and the average differential pressure shall be determined for periods not exceeding 1 hour. If pressure variations are extreme during the hour, the average shall be determined for 15-minute intervals.
(e) Mechanical devices. Mechanical devices may be substituted for the method of computing orifice meter charts set forth in this section.
Authority The provisions of this § 59.15 issued and amended under Public Utility Code,66 Pa.C.S. § § 501, 1301, 1304, 1501, 1502, 1504, 1507 and 1508.
Source The provisions of this § 59.15 amended through September 17, 1982, effective September 18, 1982, 12 Pa.B. 3291; amended December 20, 1991, effective January 21, 1992, 21 Pa.B. 5817; amended July 2, 1998, effective August 3, 1998, 28 Pa.B. 3050. Immediately preceding text appears at serial pages (232252) to (232253).
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