Mich. Admin. Code R. 460.2355 - Meter shop; design; meter testing system; standards; handling; calibration cards; calibrated orifices

Rule 55.

(1) A utility shall maintain or designate a meter shop within Michigan for the purpose of inspecting, testing, and repairing meters. The shop must be open for inspection by authorized representatives of the commission at all reasonable times. A utility may obtain approval from the commission to have its meters tested outside of Michigan upon showing, to the satisfaction of the commission, that the meter test facilities so utilized are in compliance with these rules. Records of test results must be maintained in Michigan or the administrative headquarters of the utility.

(2) The area within the meter shop that is used for the testing of meters must be designed so that the meters and meter-testing equipment are protected from drafts and excessive changes in temperature. The meters to be tested must be stored in such a manner that the temperature of the meters is substantially the same as the temperature of the prover.

(3) A utility shall own and maintain, or have access to, a meter-testing system (working standard) of an approved type, subject to all of the following provisions:

(a) Means must be provided to maintain the temperature of the liquid in a meter-testing system at substantially the same level as the ambient temperature in the prover area.

(b) The meter-testing system must be maintained in good condition and in correct adjustment so that it is capable of determining the accuracy of any service meter to plus or minus 0.5%.

(c) A utility may use a properly calibrated test meter or transfer prover or may use a properly designed flow prover for testing meters.

(4) Meter-testing systems (working standards) must be checked by comparison with a secondary standard. Both of the following provisions must be complied with:

(a) At least once every 5 years, bell and flow provers must be checked with a 1-cubic foot bottle or must be calibrated by dimensional measurement or any other test that is approved by the commission. The accuracy of the secondary standard that is used must be traceable to the National Institute of Standards and Technology.

(b) At least once every 10 years, rotary displacement transfer provers must be checked with a standard that has its calibration traceable to the National Institute of Standards and Technology or must be checked by any other suitable test that is approved by the commission.

(5) Extreme care must be exercised in the use and handling of standards to ensure that their accuracy is maintained.

(6) Each standard must have a certificate or calibration card which must be duly signed and dated and which must record the corrections that were required to compensate for errors found on the last test.

(7) A utility shall have properly calibrated orifices to achieve the rates of flow required to test the meters on its system.

Notes

Mich. Admin. Code R. 460.2355

1979 AC; 1993 AACS; 2020 MR 17, Eff. 9/3/2020