N.M. Code R. § 17.10.650.13

Current through Register Vol. 35, No. 16, August 27, 2024

Section 17.10.650.13 - INSPECTIONS AND TESTS

A.Utility inspections and tests: Each utility shall make inspections and tests of meters and associated metering devices as follows:

(1) Pre-installation inspections and tests: Every meter and associated metering device shall be inspected and tested in the utility's meter shop before being placed in service, and the accuracy of each meter shall be within the tolerances permitted by Subsection B of 17.10.650.13 NMAC.

(2) As-found tests: All meters and associated metering devices shall be tested before they are adjusted or repaired, after they are removed from service, except when transferred from one service location to another without testing, as permitted by Subsection D of 17.10.650.10 NMAC. Excepted are those meters which are damaged beyond testing. Such tests shall be made before the meters and associate metering devices are adjusted, repaired, or retired. It will not be mandatory to test meters scheduled for retirement unless there is cause to suspect the accuracy of the meter.

(3) Leak tests: Repaired meters and meters that have been removed from service shall be leak tested prior to installation except when a meter is moved from one location to another without testing in cases permitted by Subsection D of 17.10.650.10 NMAC, unless the utility has reasonable grounds for believing that some particular meter may be leaking. New meters shall be leak tested, but testing may be conducted in accordance with a sampling method acceptable to the commission. Each meter tested shall be subjected to an internal pressure of at least 20" W.C. and checked for the presence of leaks by one of the following tests:

(a) immersion test;

(b) soap test; or

(c) pressure drop test of a type acceptable to the commission.

(4) Request tests: Upon request by a customer the utility shall test the meter serving them. If the meter has been tested within the last 18 months or within a shorter applicable periodic testing interval specified in Paragraph (5) of Subsection A of 17.10.650.13 NMAC, the utility may charge the customer the applicable amount provided for in its filed rules, such charge to be refunded to the customer whenever the meter proves to be in excess of two percent in error.

(a) The customer shall be advised that the customer or their representative may be present when the meter is tested.

(b) A complete record of each test shall be kept on file by the utility.

(5) Periodic tests: Unless otherwise authorized by the commission each utility shall make periodic tests of meters, associated devices, and instruments to assure their accuracy. Such tests shall be scheduled within the calendar year or earlier when the interval is stated in years; or within the calendar month or earlier when the interval is stated in months. The basic periodic test interval shall not be longer than provided for in the following schedule. (Note: maintenance programs suggested by manufacturers of the following meters and devices should be followed carefully.)

(a) Positive displacement meters.

(i) Up to 250 CF/hr. 10 yrs.

(ii) 250 to 1500 CF/hr. seven yrs.

(iii) 1500 to 3000 CF/hr. five yrs.

(iv) 3000 to 5000 CF/hr. two yrs.

(v) Over 5000 CF/hr. one yr.

(b) Orifice meters six mos.

(c) Base pressure correcting devices 24 mos.

(d) Base volume correcting devices 24 mos.

(e) Secondary standards.

(i) Test bottle, one cubic ft. 10 yrs.

(ii) Dead weight testers 10 yrs.

(f) Working standards.

(i) Bell provers three yrs.

(ii) Rotary displacement test meters five yrs.

(iii) Flow provers five yrs.

(iv) Laboratory quality indicating pressure gauges six mos.

(6) The basic periodic test interval for positive displacement meters may be extended under the following circumstances:

(a) The utility must submit a written application requesting such extension.

(b) Such application must show the results of testing meters at the periodic test intervals for several years, and the test results must show that the meters are maintaining a high degree of accuracy.

(c) The extended interval for meter tests shall be determined by the commission, and the utility shall report annually, or as may be required, the accuracy status of such meters during the extended interval.

(d) Any authorized extension of the basic periodic test interval is subject to cancellation at any time; upon such cancellation the test interval shall be determined by the commission, but such interval shall not be less than the requirements of Paragraph (5) of this subsection.

B.Test procedures and accuracies: Meters and associated metering devices shall be tested at the points and adjusted to the tolerances prescribed below. The test of any unit of metering equipment shall consist of a comparison of its accuracy with the accuracy of a standard. The commission will use the applicable provisions of the standard listed in Subsection B of 17.10.650.12 NMAC as criteria of accepted good practice in testing meters.

(1) Positive displacement meters.

(a) Accuracy at test points.

(i) Flow Adjusted to within.

(ii) Check flow one and one-half percent

(iii) Not less than full rated flow one and one-half percent

(b) Overall accuracy: The overall accuracy at check flow and the accuracy at not less than full rated flow shall agree within one percent.

(2) Orifice meters: Accuracy at test points must be within two percent plus or minus.

(3) Timing devices: All recording type meters and associated instruments which have a timing element that serves to record the time at which measurements take place must be adjusted so that the timing element is not in error more than plus or minus four minutes in 24 hours.

(4) General:

(a) All meters and associated metering devices when tested shall be adjusted as closely as practicable to the condition of zero error.

(b) All tolerances are to be interpreted as maximum permissible variations from the condition of zero error. In making adjustments no advantages of the prescribed tolerance limits shall be taken.

C.Facilities and equipment for meter testing: Each utility shall maintain or designate a meter shop for the purpose of inspecting, testing, and repairing meters. The shop shall be open for inspection by authorized representatives of the commission at all reasonable times, and the facilities and equipment as well as the methods of measurement and testing employed shall be subject to the approval of the commission.

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

(2) Working standards: Each utility shall own and maintain or have access to at least one approved bell type prover of adequate capacity, and all other equipment necessary to test meters shall be installed in the meter room.

(a) Means shall be provided to maintain the temperature of the liquid in the meter prover at substantially the same level as the ambient temperature in the prover room.

(b) The meter prover shall be maintained in good condition and correct adjustment so that it is capable of determining the accuracy of any service meter to within one half of one percent.

(c) Each utility which has meters too large for testing on a five cubic foot bell prover may use a properly calibrated test meter or a properly designed flow prover for testing the large meters.

(3) Working standards must be checked periodically (see Paragraph (5) of Subsection A of 17.10.650.13 NMAC) by comparison with a secondary standard.

(a) Bell provers must be checked with a one cubic foot bottle which has been calibrated by the national bureau of standards or by the strapping method.

(b) Rotary displacement test meters must be checked with a bell prover of adequate capacity which has been checked as provided in Subparagraph (a) of this paragraph.

(4) Extreme care must be exercised in the use and handling of standards to assure that their accuracy is not disturbed.

(5) Each standard shall be accompanied at all times by a certificate or calibration card, duly signed and dated, on which are recorded the corrections required to compensate for errors found at the customary test points at the time of the last previous test.

(6) Each utility must have such properly calibrated orifices as may be necessary to achieve the rates of flow required to test the meters on its system.

D.Records of meters and associated metering devices: Each utility shall maintain records of the following data, where applicable, for each meter and associated metering devices according to 17.3.310 NMAC:

(1) the complete identification--manufacturer, number, type, capacity, multiplier, constants, and pressure rating; and

(2) the dates of installation and removal from service together with the location.

E.Meter test records: Each utility shall maintain records of meter tests for the duration set forth in 17.3.310 NMAC. The records shall include the following:

(1) the date and reason for test;

(2) the reading of the meter before making any test;

(3) the accuracy "as found" at check and full rated flow;

(4) the accuracy "as left" at check and full rated flow; and

(5) in the event the test of the meter is made by using a standard meter or prover, the utility shall retain all data taken at the time of the test in sufficiently complete forms to permit convenient checking of the test methods and calculations.

N.M. Code R. § 17.10.650.13

6-30-88; 17.10.650.13 NMAC - Rn, NMPSC 650.32-650.36 & A, 6-15-05, Adopted by New Mexico Register, Volume XXXI, Issue 21, November 10, 2020, eff. 11/10/2020