HomeMy WebLinkAbout20170905Attachment 93B.pdfAVISTA UTILITIES
GAS METER
MEASUREMENT
PERFORMANCE REPORT
2016 RESULTS
Submitted 8/23/17
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GAS METER MEASUREMENT PERFORMANCE
REPORT
GAS METER PERFORMANCE FOR THE PERIOD JANUARY 1 – DECEMBER 31, 2016
TABLE OF CONTENTS
1. SCOPE ..................................................................................................................................................................... 3
2. GENERAL .............................................................................................................................................................. 3
3. DEFINITIONS ........................................................................................................................................................ 6
4. RANDOM SAMPLING METER PERFORMANCE ......................................................................................... 7
SUMMARY OF METERS 1000 CFH AND SMALLER ......................................................................................... 7
FAILED METER FAMILIES ................................................................................................................................... 8
5. PRESCRIPTIVE TESTING .................................................................................................................................. 9
LARGE DIAPHRAGM METERES ......................................................................................................................... 9
DIAPHRAGM METERS 1001 - 3000 CFH ................................................................................................... 9
DIAPHRAGM METERS GREATER THAN 3000 CFH ............................................................................... 9
ROTARY METERS ................................................................................................................................................ 10
ROTARY METER RESULTS ...................................................................................................................... 10
TURBINE METERS ............................................................................................................................................... 10
TURBINE METER RESULTS ..................................................................................................................... 10
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1. SCOPE
This report covers the methodology, test results, and proceedings of the Avista gas meter measurement
performance testing program for in-service meters for the period from January 1, 2016 thru December 31,
2016.
2. GENERAL
COMPLIANCE
Washington: Gas meter testing requirements for Avista are promulgated by Washington Administrative
Code, Chapter 480-90 “Gas companies - operations”, Section 333 (Initial accuracy of meters), Section
338 (Metering tolerance), Section 343 (Statement of meter test procedures), and Section 348 (Frequency
of periodic meter tests. Avista gas tariff Rule No. 170, Section 20, effective November 30, 2011, has
been approved and is in compliance with the requirements of WAC 480-90 and prescribes the minimum
inspection and testing requirements.
Oregon: Gas meter testing requirements for Avista are promulgated by Oregon Administrative Rules,
Chapter 860, Division 023 “Service Standards”, Section 0015 (Testing Gas and Electric Meters). Avista
gas tariff Rule No. 18 with varying approval dates between January 1, 2009 and January 1, 2012 has been
approved is in compliance with the requirements of OAR 860-023-0015 and prescribes the minimum
inspection and testing requirements.
Idaho: Gas meter testing requirements for Avista are promulgated by Title 31, Chapter 1, “Service Rules
for Gas Utilities”, IDAPA 31.31.01.000, Rules 151-200 (Standards for service). Avista gas meter testing
program is completed in accordance with IDAPA 31.31.01.0000* and Avista Gas Meter Measurement
Performance Program.
*(Rule 152 – Avista’s random sampling program is completed for meters 0-1000 CFH and in
accordance with ANSI/ASQ Z1.9, Inspection by Variables. The IDAPA rule refers to the
obsolete military standard 105D, Inspection by Attributes.)
SIGNIFICANT UPDATES OR CHANGES
Also as a result of the Maximo implementation, some of the meter counts contained in this report may
differ when comparing the beginning of the year to the end of the year.
In 2017, this report was changed to only include a summary of the test results and to provide details for
the following year’s test plan. The details of each individual test and the ANSI Z1.9 calculations are
available in spreadsheets that are stored on the network drive c01d44/GASENGINEER/GAS DESIGN
DOCUMENTATION/Gas Meter Measurement Performance PMC.
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METER CATEGORIES
Meter populations exist within the following gas meter categories. Meter category inspection and testing
requirements are summarized as follows for installed meters:
• Domestic (Diaphragm) Meters 1000 CFH and smaller – Random sampling and proof testing per
ANSI Z1.9, testing to begin during the 10th test year after meter installation.
• Diaphragm Meters 1001 – 3000 CFH – Prescriptively inspected and proof tested every ten (10)
years or sooner.
• Diaphragm Meters >3000 CFH - Prescriptively inspected and proof tested every five (5) years or
sooner.
• Rotary Meters – Prescriptively inspected and tested via differential testing every five (5) years or
sooner.
• Turbine Meters – Prescriptively inspected and tested annually via a spin test and every ten (10)
years via a calibration.
METER PERFORMANCE REQUIREMENTS
Random Sampling - Meter inspection performance for randomly tested meters is per ANSI Z1.9 with a
tolerance of +/- 2%. The intent of the testing standard is to verify the following:
Overall Performance - Verify with approximately 90% certainty, that the portion of non-
conforming meters does not exceed 10% of any installed meter population. For overall
performance, equal weight is given to both the upper and lower specification limit (fast and slow
reads are equally weighted and are averaged). The “standard deviation – double specification
limit method with variability unknown” as detailed in the ANSI Z1.9 shall be used to determine
the overall acceptability of a meter population. Acceptable Quality Limit (AQL) for analysis will
equal 10.0.
Fast Direction Performance- Verify with approximately 90% certainty that the portion of non-
conforming fast meters does not exceed 10% of any installed meter population. For testing equal
weight is given to both the upper and lower specification limit (fast and slow reads are equally
weighted and are averaged). The “standard deviation – single specification limit method with
variability unknown” as detailed in the ANSI Z1.9 shall be used to determine the fast direction
performance (disadvantageous to the consumer) acceptability of a meter population. Acceptable
Quality Limit (AQL) for analysis will equal 10.0.
Prescriptive Testing - Meter inspection performance for diaphragm meters >1000 CFH, rotary, and
turbine meters that are proof tested shall be 100% +/- 2%. Rotary meters that are differential tested shall
determine that the meter is operating within 150% of the manufactures differential pressure requirements
at the metering pressure. Turbine meter spin tests shall exceed the manufactures minimum prescribed
spin duration.
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ANSI Z1.9 TESTING REQUIREMENTS
A summary of the meter population performance requirements per ANSI Z1.9 are as follows:
Meters to be included in the meter test population will be selected at random.
All meters within the meter test population are eligible for testing except that individual meters
tested within preceding five (5) years are excluded from random sample selection.
Annual meter population sampling requirements will be as prescribed by the ANSI Z1.9 and in
accordance with appropriate meter testing category the meter population falls within.
Meter Testing Categories
o “Normal Inspection” – Default meter population sample category as detailed by the ANSI
Z1.9. Meter population sampling shall be switched from “Normal” to “Tightened” or
“Normal” to “Reduced” as described below.
o “Tightened Inspection” – Increased meter population sampling as detailed by the
standard when 2 out of 5 preceding annual tests have been found non-conforming. Meter
population sampling may be returned to “Normal” from “Tightened” when 5 consecutive
batches have been determined acceptable.
o “Reduced Inspection” – Decreased meter population sampling as detail by ANSI Z1.9.
Meters with a 5 year test history are eligible for reduced inspection requirements. Meter
population sampling may be switched from “Normal” to “Reduced” when 5 annual tests
have been found acceptable. Meter population sampling shall be returned from
“Reduced” to “Normal” if a single annual sampling is rejected.
Failure of a meter population – A meter population shall be deemed failed when:
o Three (3) consecutive yearly inspections for a population under tightened inspection are
found non-conforming for overall performance or;
o Two (2) consecutive yearly inspections fail tightened inspection as non-conforming for
fast meters or;
o Two (2) consecutive yearly inspections exceed a total of 20% non-conforming meters
(total of fast and slow meters) under tightened inspection.
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3. DEFINITIONS
PMC – Refers to Avista’s gas meter measurement performance program, commonly referred to as a
Periodic Meter Change-out (PMC) program.
Meter Population – Often referred to as Meter Family. Group of meters from the same manufacture,
same model, and manufactured in the same year. Temperature Compensation does not distinguish a new
population (i.e. 1995 AC250TC is the same as 1995 AC250).
Open Test – Meter proof test completed at 100% of meter rated capacity or the maximum rated capacity
of the test equipment.
Check Test – Meter proof test completed at approximately 20% of the meter rated capacity.
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4. RANDOM SAMPLING METER PERFORMANCE
SUMMARY OF METERS 1000 CFH AND SMALLER
Beginning of Report Year, In-Service Meters at Beginning of Test Year
Total Number of Meters 342,837
Total Number of Families, Including Families Not Eligible For Test (a) 218
Number of Test Families >= 10 yrs old (b) 178
Number of Test Families w/ Size More Than or Equal to 10 (c) 207
Number of Test Families w/ Size Less Than 10 (c) 8
Number of Test Families Administratively Declared Failed (d) 5
Number of Test Families >= 10 yrs, Size>10, and Not Declared Failed (e) 168
Failed Family By Performance (f) 0
Meter Families That Were Scheduled For Normal Inspection 77
Meter Families That Were Scheduled For Reduced Inspection 80
Meter Families That Were Scheduled For Tightened Inspection 12
Report Year Meter Testing Results
Number of Meters Tested 8703
Number of Meters Passed, (within +/- 2%) 7916
Number of Meters Failed, (> +/- 2%, but less than +/-10%) 768
Number of Meters, Uniquely Defective Test Result, (greater than +/- 10%) 19
Plan For The Following Year’s Testing
Total Number of Meters 349,926
Total Number of Families, Including Families Not Eligible For Test (a) 223
Number of Test Families >= 10 Years Old (b) 184
Number of Test Families w/ Size More Than or Equal to 10 (c) 149
Number of Test Families w/ Size Less Than 10 (c) 35
Number of Test Families Administratively Declared Failed (d) 0
Number of Test Families >= 10 yrs, Size > 10, And Not Historically Failed (e) 146
Failed Family By Performance (f) 3
Meter Families Scheduled For Normal Inspection 121
Meter Families Scheduled For Reduced Inspection 80
Meter Families Scheduled For Tightened Inspection 17
Number of Meters to be Tested 4041
(a) Total number of meter populations includes meter test families that are less than 10 years old and are
not yet subject to test requirements.
(b) Number of Meter Test Populations >= 10 years old (i.e. 2017 test year would be 2006 and older)
(c) Avista has many test populations with less than 10 members. Random sampling of those populations
results in repeated testing of meters with no perceived benefit to customers. Avista has begun a
prioritized program which is replacing meters that are more than 20 years old in populations of less than
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10 meters. Small populations less than 20 years old are tested but with the restriction that a meter will not
be retested within five (5) years.
(d) Number of meter families that were declared failed for administrative reasons. Includes families with
less than 10 meters population and meter populations that were observed to be trending towards failure
that are more than 20 years old. Meter populations trending towards failure, but not yet failed by test
data, were generally older populations that had been mixed with other populations when the testing
program was based on last install date rather than manufactured date. The revision in test family
grouping uncovered these suspect families which the earlier test family criteria had hidden. In some
instances, not enough tests had been performed to statistically declare the family failed; however, manual
inspection of results indicated some obvious trend to failure for those groups. Avista has chosen to
proactively begin retirement of meter test populations with these characteristics.
(e) Number of meter test families subject to standard random testing procedures: over 10 years old, with
more than 10 members, and not a failed family.
(f) Meters populations failed due to performance.
FAILED METER FAMILIES
Family
Number of Meters Failed for:
Performance Administrative Reasons
AL175_1964 646 -
AL175_1965 578 -
AL175_1969 2140 -
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5. PRESCRIPTIVE TESTING
LARGE DIAPHRAGM METERES
DIAPHRAGM METERS 1001 - 3000 CFH
10-Year Periodic Testing
Meter population (1) 1408
Meters tested and adjusted (2) 231
Meters failed (2) 26
(1) At the beginning of test year
(2) At the end of the test year (does not include > +/- 10%)
DIAPHRAGM METERS GREATER THAN 3000 CFH
5-Year Periodic Testing
Meter population (1) 170
Meters tested and adjusted (2) 28
Meters failed (2) 0
(1) At the beginning of test year
(2) At the end of the test year (does not include > +/- 10%)
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ROTARY METERS
ROTARY METER RESULTS
5-Year Periodic Testing
Meter population (1) 1657
Meters tested and adjusted (2) 486
Meters failed (2) 0
(1) At the beginning of test year
(2) At the end of the test year (does not include > +/- 10%)
TURBINE METERS
TURBINE METER RESULTS
Annual Testing
Meter population (1) 63
Meters tested (2) 63
Meters failed (2) 0
10 Yr Testing
Meters tested and adjusted (2) 8
Meters failed (2) 0
(1) At the beginning of test year
(2) At the end of the test year (does not include > +/- 10%)
End of Report
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