N.M. Admin. Code § 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.
Notes
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