1. (a) Pressure and temperature control.

   1. (1) The pressure differential between a prover and meter connection shall not exceed four-tenths of an inch of water column (0.4" W.C.) at any flow rate without correction for pressure difference at that flow rate.
   2. (2) The pressure variation within the prover bell shall not exceed five-hundredths of an inch of water column (0.05" W.C.) throughout the travel of the bell.
   3. (3) If the meter, prover, and proving environment are at temperatures differing by more than five-tenths of a degree Fahrenheit (0.5° F), temperature correction shall be applied.

   4. (4)

      1. (A) If the temperature of the proving environment is changing by more than one degree Fahrenheit (1° F) per hour, testing shall not be performed.
      2. (B) Temporary fluctuations in excess of one degree Fahrenheit (1° F) are permitted.

2. (b) Calibration of meter proving equipment.

   1. (1) Calibration of meter proving systems shall be conducted under known and controlled conditions.
   2. (2) The accuracy of volumetric containers, tapes, scales, and other measurement devices shall be traceable to the National Institute of Standards and Technology.

   3. (3) Displacement provers.

      1. (A) Displacement provers shall be calibrated:

3. (i) When first installed; and

   1. (ii) Following alterations, damage, or repairs that may affect the accuracy.

      1. (B) Daily leakage tests shall be made and a weekly accuracy test shall be made with a meter of known accuracy.
      2. (C) If the test results differ by more than five-tenths of a percent (0.5%) from the test meter accuracy, cause of the error shall be determined and necessary corrections made before using the prover.

   2. (4) Transfer provers.

      1. (A)

         1. (i) Transfer prover master meters shall be recalibrated at least once every five (5) years under controlled temperature, pressure, and flowing conditions.
         2. (ii) The accuracy of the prover shall be determined by a sufficient number of tests to correctly determine a flow rate/accuracy curve over the full range for which it will be used.

      2. (B)

         1. (i) Calibration tests must be performed using a reference standard of known accuracy such as a bell-type or piston-type prover of known adequate capacity.
         2. (ii) Pressure and temperature differences between the reference standard and the transfer prover meter shall be recorded at each flow rate and the volume appropriately corrected.
      3. (C) The transfer prover sensing and timing equipment, temperature sensor and readout, pressure sensor and readout, and timing indicators shall be checked and calibrated in accordance with the manufacturer's recommendations.

Codification Notes: This section was promulgated as Rule 7.03 of the Special Rules — Gas prior to codification in the Code of Arkansas Rules.