Current through Vol. 25-4, March 15, 2025
Rule 51. Inspections and tests of meters and associated
metering devices must be made by, or on behalf of, each utility as
follows:
(a) A meter or an associated
metering device that is not included as a part of the meter, or both, must be
inspected and tested before being placed in service, and the error must not be
more than 1.0%.
(b) A meter or an
associated metering device, or both, must be tested after it is removed from
service. These tests must be made before the meter or associated metering
device is adjusted, repaired, or retired.
(c) A repaired meter or a meter that is
removed from service must be leak-tested before being returned to service,
subject to the following requirements:
(i) If
tested in the field, a meter must be tested at the actual meter operating
pressure of the system.
(ii) If
tested in the shop, a meter must be subjected to an internal pressure test of,
at a minimum, 3.0 pounds per square inch gauge pressure. In addition, any meter
that will operate above 3.0 pounds per square inch gauge pressure must be so
marked on the meter and must be subjected to 1 of the following tests:
(A) An internal pressure test of, at a
minimum, the manufacturers rated operating pressure.
(B) An internal pressure test at 10% above
the maximum operating pressure to which the meter could be subjected.
(C) Any suitable test that is approved by the
commission.
(iii) During
the pressure test, the meter must be checked for leaks by 1 of the following
tests:
(C) Pressure drop test of a type that is
approved by the commission.
(d) As part of its rate book, a utility shall
file, for commission approval, a statement of its policy with regard to testing
meter accuracy upon a customers request. In the absence of a filed policy
approved by the commission, the utility shall adhere to both of the following
provisions:
(i) A utility shall test meter
accuracy upon the request of a customer if the customer does not request a test
more than once every 2 years and if the customer agrees to accept the results
of the test as the basis for determining the difference claimed. A charge must
not be made to the customer for the first test in any 5-year period, but if
subsequent tests during the same period, for the same customer, show the meter
to be within the allowable limits of accuracy, the utility may charge the
customer an amount for subsequent tests which is uniform and which does not
exceed the utility's direct cost thereof, plus a reasonable charge for
administrative overhead. The customer may be present at the test if he or she
makes a request before the test.
(ii) A written report must be made to the
customer by the utility. The report must state the results of the test. A
record of the test must be kept by the utility.
(e) A utility shall make periodic tests of
meters, associated devices, and instruments to ensure their accuracy. The tests
must be conducted according to the following schedule, unless otherwise
approved by the commission. A utility may test meters more frequently than
provided in the following schedule without commission approval:
(i) Positive displacement diaphragm-type
meters that have capacities of less than 500 cubic feet per hour, not to exceed
123 months.
(ii) Positive
displacement diaphragm-type meters that have capacities over 500 cubic feet per
hour, not to exceed 87 months.
(iii) Rotary meters that have capacities of
less than 15,000 cubic feet per hour, which may be tested in place, not to
exceed 51 months.
(iv) Rotary
meters that have capacities of 15,000 cubic feet per hour or more, which may be
tested in place, not to exceed 27 months.
(v) Other meter types, such as turbine,
Coriolis, 4-Path or greater ultrasonic, or other metering technology, which may
be tested in place when possible, not to exceed 27 months.
(vi) Orifice meters, 2 times per year with
intervals not to exceed 7.5 months.
(vii) Gas instruments, such as base volume,
base pressure, and base temperature-correcting devices, must be checked for
calibration at intervals that correspond to the schedule for their associated
meters. The testing interval must not exceed 51 months.
(viii) Test bottles, deadweight testers,
certified test meters, not to exceed 123 months.
(ix) Meter testing systems must be calibrated
when first installed and after alterations, damages, or repairs that might
affect accuracy. To ensure that the accuracy of a meter testing system is
maintained on a continuous basis, a daily leakage test must be made and a
weekly accuracy test with a comparison meter of known accuracy must be made. If
the test results differ by more than plus or minus 0.5% from the comparison
meter, the cause of the error must be determined and necessary corrections must
be made before the system is reused. The comparison meter must be checked at an
interval of 1 year not to exceed 13 months.
(f) Utilities shall maintain records of
meters that have been tested during the preceding calendar year and shall make
this information available to the commission upon request. The record must
contain all of the following information for each meter tested:
(iv) Customer class, either commercial and
industrial or residential.
(v)
Results of the meter test.
(vi)
Whether the meter was retired and if so the reasons for the
retirement.
