NZS 5259:2015 New Zealand Standard Gas measurement Superseding NZS 5259:2004 NZS 5259:2015
Committee representation This standard was prepared under the supervision of the P 5259 Committee the Standards Council established under the Standards Act 1988. The committee consisted of representatives of the following nominating organisations. Gas Industry Company Ltd Ian Wilson GasNet Ltd Wayne Armishaw Genesis Energy David Whitfield Itron Metering Systems Singapore Pte Ltd Ross Parker Landis+Gyr Ltd Mark Grigor Master Plumbers, Gasfitters and Drainlayers NZ Inc. Darren Smith New Zealand Council of Elders Pat Cunniffe New Zealand Institution of Gas Engineers Bill Miller Powerco Ltd Bruce Monk Vector Ltd Len Rodenburg WorkSafe New Zealand (Energy Safety) Paul Stannard Acknowledgement Standards New Zealand gratefully acknowledges the contribution of time and expertise from all those involved in developing this standard. Cover photographs: Top left, courtesy of Bruce Monk, Powerco Ltd Top right, courtesy of Mark Grigor, Landis+Gyr Ltd Both bottom left and bottom right, courtesy of Wayne Armishaw, GasNet Ltd. Copyright The copyright of this document is the property of the Standards Council. No part of this document may be reproduced by photocopying or by any other means without the prior written permission of the Chief Executive of Standards New Zealand, unless the circumstances are covered by Part 3 of the Copyright Act 1994. Standards New Zealand will vigorously defend the copyright in this standard. Every person who breaches Standards New Zealand s copyright may be liable, under section 131(5)(a) of the Copyright Act 1994, to a fine not exceeding $10,000 for every infringing copy to which the offence relates, but not exceeding $150,000 for the same transaction, or to imprisonment for a term not exceeding 5 years. Those in breach under section 131(5)(b) of the Copyright Act 1994 may be liable to a fine not exceeding $150,000 or to imprisonment for a term not exceeding 5 years. If there has been a flagrant breach of copyright, Standards New Zealand may also seek additional damages from the infringing party, in addition to obtaining injunctive relief and an account of profits. Published by Standards New Zealand, the trading arm of the Standards Council, Private Bag 2439, Wellington 6140. Telephone: (04) 498 5990; Fax: (04) 498 5994; Website: www.standards.co.nz. AMENDMENTS No. Date of issue Description Entered by, and date
New Zealand Standard Gas measurement Superseding NZS 5259:2004 ISBN (Print) 978-1-77664-204-5 ISBN (PDF) 978-1-77664-205-2
Contents Referenced documents... iv Latest revisions... vi Review of standards... vi Related documents... vi Foreword... vii Outcome statement...viii Section 1 General...1 1.1 Scope...1 1.2 Application...2 1.3 Definitions...2 1.4 Abbreviations...9 1.5 Interpretation...9 1.6 Units of measurement of energy...9 2 Performance requirements...10 2.1 Purpose...10 2.2 General requirements of the gas measurement system...10 2.3 Specific suitability requirements...12 2.4 Metrological performance of gas measurement systems and components...13 2.5 Testing...15 2.6 GMS design, construction, and transportation...16 2.7 GMS operation and maintenance...16 2.8 Documentation...16 2.9 Competency... 17 2.10 Auditing... 17 2.11 Conversion of measured units to energy...18 2.12 Conversion of actual volume to standard volume...18 2.13 Conversion of standard volume to energy...21 2.14 Conversion of measured mass to standard volume...21 2.15 Conversion of measured mass directly to energy...22 3 A means of compliance...22 3.1 Purpose...22 3.2 General safety...24 3.3 GMS specification and design...24 3.4 Specific meter, conversion device, and regulator tests...28 3.5 GMS installation...37 3.6 GMS operation and maintenance...38 3.7 Documentation... 41 3.8 Conversion factor value determination and application... 41 ii
Appendix A Commonly used conversion factors (Normative)...47 B C D E F G H J K L Guidance on the accuracy requirements for the time parameter of time-stamped data (Informative)...48 Compliance checklist (Informative)...50 Installation tests for specific types of device (Informative)...55 Test equipment and test area requirements for testing conversion devices (Normative)...56 Specific requirements for the transfer prover and transfer prover test area (Normative)...58 Specific requirements for bell provers and bell prover test areas (Normative)...63 External leakage test (Normative)...66 Accuracy testing of meters by transfer prover (Informative)...67 Accuracy testing of gas meters by bell prover (Informative)...69 Testing of conversion devices (Informative)...71 Table 1 Transitional flow rate...4 2 Maximum permissible errors for meters (% of reading)...13 3 Maximum permissible errors for conversions (% of conversion)... 14 4 Selection of equipment...23 5 Accuracy of registration test points...33 6 Accuracy of conversion test points...35 7 Acceptance testing intervals...38 8 Acceptable quality levels... 41 Figure 1 Conversion of actual volume into energy...20 F1 F2 Schematic representation of a low pressure transfer prover...58 Control chart (example only)...61 iii
Referenced documents Reference is made in this document to the following: New Zealand standards NZS 5258:2003 NZS 5435:1996 NZS 5442:2008 NZS 7901:2014 NZS ISO/IEC 17025:2005 Gas distribution networks Specification for liquefied petroleum gas (LPG) Specification for reticulated natural gas Electricity and gas industries Safety management systems for public safety General requirements for the competence of testing and calibration laboratories Joint Australian/New Zealand standards AS/NZS 4645:- - - - Part 1:2008 Part 2:2008 AS/NZS 4944:2006 AS/NZS 5601:- - - - Part 1:2013 AS/NZS ISO 10012:2004 AS/NZS CSPR 11:2011 Gas distribution networks Network management Steel pipe systems Gas meters In-service compliance testing Gas installations General installations Measurement management systems Requirements for measurement processes and measuring equipment Industrial, scientific and medical equipment Radiofrequency disturbance characteristics Limits and methods of measurement International standards ISO 6976:1995 ISO 9951:1993 ISO 12213: Part 1:2006 Part 2:2006 Part 3:2006 OIML R 137:- - - - Part 1:2012 Part 2:2012 Part 3:2014 OIML R 140:2007 Natural gas Calculation of calorific values, density, relative density, and Wobbe index from composition Measurement of gas flow in closed conduits Turbine meters Natural gas Calculation of compression factor Introduction and guidelines Calculation using molar-composition analysis Calculation using physical properties Gas meters Metrological and technical requirements Metrological controls and performance tests Test report format Measuring systems for gaseous fuel iv
American standards ANSI B109.1:2000 Diaphragm-type gas displacement meters (under 500 cubic feet per hour capacity) ANSI B109.2:2000 ANSI B109.3:2000 ANSI B109.4:1998 Diaphragm-type gas displacement meters (500 cubic feet per hour capacity and over) Rotary-type gas displacement meters Self-operated diaphragm-type natural gas service regulators British standards BS EN 88:---- Part 2:2007 BS EN 334:2005 BS EN 1359:1999 BS EN 12261:2002 BS EN 12405:- - - - Part 1:2005 BS EN 12480:2015 BS EN 14236:2007 Pressure regulators and associated safety devices for gas appliances Pressure regulators for inlet pressures above 500 mbar up to and including 5 bar Gas pressure regulators for inlet pressures up to 100 bar Gas meters. Diaphragm gas meters Gas meters. Turbine gas meters Gas meters. Conversion devices Volume conversion Gas meters. Rotary displacement gas meters Ultrasonic domestic gas meters Other publications American Gas Association. AGA Report No. 7 (AGA 7) Measurement of natural gas by turbine meter. Washington, DC: American Gas Association, 2006. American Gas Association. AGA Report No. 8 (AGA 8) Compressibility factor of natural gas and related hydrocarbon gases. 2nd edition. Washington, DC: American Gas Association, 1992. American Gas Association. AGA Report No. 9 (AGA 9) Measurement of gas by multipath ultrasonic meters. Washington, DC: American Gas Association, 2007. American Gas Association. AGA Report No. 11 (AGA 11) Measurement of natural gas by Coriolis meter. 2nd ed. Washington, DC: American Gas Association, 2013. Bureau International des Poids et Mesures. Evaluation of measurement data Guide to the expression of uncertainty in measurement (GUM). 1st ed. Sèvres, Paris: Bureau International des Poids et Mesures, 2008. Convention of the Metre, 1875. v
Gas Industry Company Ltd. Gas (Downstream Reconciliation) Rules 2008 Billing factors guideline note, version 2.0, 22 December 2011. Gas Industry Company Ltd. Retrieved from www.gasindustry.co.nz/dmsdocument/2849 (8 October 2015). Measurement Canada. LMB-EG-08 Specifications for approval of type of gas meters and auxiliary devices. Ottawa: Measurement Canada, 2011. Zimmerman, R H. Manual for the determination of super-compressibility factors for natural gas, PAR research project NX-19 (AGA NX-19). Washington, DC: American Gas Association, 1962. New Zealand legislation Electricity Act 1992 Electricity (Safety) Regulations 2010 Gas Act 1992 Gas (Safety and Measurement) Regulations 2010 Telecommunications Act 2001 Websites www.gasindustry.co.nz www.legislation.govt.nz www.oatis.co.nz Latest revisions The users of this standard should ensure that their copies of the above-mentioned standards are the latest revisions. Amendments to referenced New Zealand and Joint Australian/New Zealand standards can be found on www.standards.co.nz. Review of standards Suggestions for improvement of this standard will be welcomed. They should be sent to the Chief Executive, Standards New Zealand, Private Bag 2439, Wellington 6140. Related documents The following publications contain information relevant to this standard. BS EN ISO 15970:2014 Natural Gas Measurement of properties. Volumetric properties: density, pressure, temperature and compression factor Measurement Canada. Bulletin G-18 (rev.3) Reverification periods for gas meters, ancillary devices and metering installations. Ottawa: Measurement Canada, 2011. vi
Foreword This standard is a revision of NZS 5259:2004 Gas measurement, which is cited in the Gas (Safety and Measurement) Regulations 2010, and provides performance criteria for all gas measurement systems offering a means of compliance under the Gas Act. The purpose of this standard is to provide performance-based requirements for gas measurement that are useful, measurable, and repeatable as a minimum standard for the gas sector. Section 1 provides general information about the standard, section 2 contains performance requirements for the gas measurement system (GMS), and section 3 sets out a means of compliance for gas measurement. In revising the standard, the committee considered current best practice as laid out in relevant national and international standards, new and developing technologies, compliance costs, and generic development such as electrical metering. The performance requirements have been reviewed and updated to ensure that all of the existing regulatory requirements for accuracy and suitability have been incorporated. These have been extended as necessary to apply not only to the meter and conversion device but also other components of the gas measurement system. Worker competency requirements are also included. Meter test intervals have been amended to align with international standards and manufacturers specifications. The amendments reflect current technologies and measurement methods. AS/NZS 4944 is referenced as a means of complying with requirements for statistical sampling of meters with a capacity of G16 and smaller. As a result, the previous Appendix L on statistical sampling has been removed. The permissible weighted mean error for acceptance testing of meters with capacity greater than G160 is amended to match current best practice. Meters of capacities G6.5 and G16 are combined to align with AS/NZS 4944. The standard provides accuracy criteria for instruments used to determine the calorific value of a gas. Methodology and calculation of calorific value not measured by instrumentation are covered in the Gas (Downstream Reconciliation) Rules 2008 Billing factors guideline note, published by Gas Industry Company Ltd (for more information see: www.gasindustry. co.nz/dmsdocument/2849). This guideline should be updated and extended to cover matters of good industry practice that are not suitable for inclusion in a New Zealand standard, but are nonetheless potentially significant for billing accuracy. In particular, the current practice of gas retailers using gas composition information posted on the open access transmission information system (OATIS) is better suited for coverage in a guideline than for inclusion in this standard. While the standard addresses the accuracy of calorific value (CV) measurement of gas, it does not specify how CV measurements are processed to deal with the co-mingling of different gas types, or the time lags between CV measurement and the sale of that gas. Yet, these latter processes have the potential to introduce significant inaccuracies. Currently gas composition and characteristics are measured using gas chromatographs vii
(GCs) at receipt points into the transmission system, at major delivery points (such as power stations and petrochemical plants), and at a number of key locations on the transmission system. Several components of these measurements are relevant to the conversion of metered volumes to energy. These are specific gravity (SG), carbon dioxide (CO 2 ) and nitrogen (N 2 ) (used in the calculation of the compressibility factor), and CV (used in the conversion from standard volume to energy). Different parts of the transmission system have different gas types depending on which gases are being injected and co-mingled in that part of the system. There are currently 14 gas types. The transmission system operator provides a document on OATIS entitled Delivery Point Gas Types advising which gas type should be used for each area of the system. (For more information see www.oatis.co.nz. In the absence of login and password details, click on either of the two buttons under Public Information Exchange, and select Publications.) The information relevant to each gas type (that is, CV, SG, CO 2, and N 2 ) is posted on OATIS each day. It is the responsibility of each gas supplier to pick up the relevant gas type data posted on OATIS and use it to derive the relevant conversion factor F Z and CV specified in the standard. This generally involves matching the data to the billing period and deriving average values for that period. The review committee has asked Gas Industry Company Ltd, in its role as industry body under the Gas Act 1992 to describe these practices in its guideline and the review committee understands that Gas Industry Company Ltd is willing to do this, and will endeavour to update the guideline by the time this standard is published. Outcome statement The aim of this standard is to improve the accuracy of gas measurement by setting achievable, balanced performance criteria. It benefits both the gas sector and the consumer by providing a means of compliance for gas measurement systems to meet performance criteria. viii
New Zealand Standard Gas measurement 1 General 1.1 Scope This standard contains the mandatory requirements and a means of compliance for gas measurement. It includes the requirements for: (a) (b) (c) (d) (e) (f) (g) (h) Accuracy; Equipment selection; Installation; Operation; Maintenance; Testing; Conversion of measured quantities to energy; and Competency. Section 1 provides general information about the standard, including its scope, application, definitions, and how the standard is to be interpreted. Section 2 sets out performance requirements for the gas measurement system (GMS), including conversion of measured quantities of gas to energy; documentation; competency of persons working on a GMS and components, and completing conversions; auditing; and conversion of actual volume to energy. Section 3 provides means of compliance for the design, testing, installation, operation and maintenance, and documentation of the GMS. Alternative methods for establishing compliance with any or all of the section 2 requirements may be used, provided they are tested and documented to achieve compliance. The details in section 3 have been reordered to align more closely with the performance statements of section 2 and updated to reflect the latest metrology technology. Detailed testing methods and equipment arrangements are in the appendices, and an audit checklist is included to assist in assessing compliance. 1
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