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Physical Measurement Laboratory

Weights and Measures

Hydrogen: U.S. National Work Group

Hydrogen: USNWG

The USNWG works to promote, encourage, and participate in the establishment of a comprehensive set of legal metrology standards for commercial measurement of hydrogen for vehicle and other refueling applications including (1) device design, accuracy, installation, and use requirements; (2) method of sale requirements; (3) test procedures; and (4) fuel quality standards. The ultimate goal is that these standards will ensure the accuracy of measurements, enhance consumer protection, foster fair competition, and facilitate economic growth and trade.

The USNWG works through in-person meetings, conference calls, and email. The USNWG is currently accomplishing its goals through two subcommittees; one works to simultaneously refine equipment standards and test procedures and a second works on fuel specification requirements. For questions about meeting summaries and agendas please send a request to the USNWG Contact available through the Resources Helpful Hydrogen Links and Contacts listed below.

Next Meeting(s):	TBD
USNWG Operating Guideline:	USNWG HYDROGEN GUIDELINES 2-27-09
Meeting Summary(s):	October 3-4, 2007, USNWG Meeting, Gaithersburg, MD March 4-6, 2008, USNWG Meeting, West Sacramento, CA June 17-19, 2008, USNWG Meeting, Des Plaines, IL August 26-27, 2008, USNWG Meeting, Allentown, PA December 2-4, 2008, USNWG Meeting, Boulder, CO January 30, 2009, USNWG Meeting, Tele/Web Conference February 24, 2009, USNWG Meeting, Tele/Web Conference April 28-30, 2009 USNWG Meeting, West Sacramento, CA June 17, 2009 USNWG Meeting, Tele/Web Conference July 7, 2009 USNWG Meeting, Tele/Web Conference August 11-13, 2009 USNWG Meeting, Gaithersburg, MD "The Starting Point: A Discussion Paper Describing a Proposed Method of Sale and Quality Specification for Hydrogen Vehicle Fuel" (August, 2009) December 15, 2009 USNWG, Tele/Web Conference January 13, 2010 USNWG, Tele/Web Conference April 27, 2010 USNWG, Tele/Web Conference May 25, 2010 USNWG, Tele/Web Conference June 17, 2010 USNWG, Tele/Web Conference October 12, 2011, USNWG Meeting, Tele/Web Conference
Meeting Agenda(s):	July 2, 2010 USNWG Meeting, Tele/Web Conference April 19, 2011 USNWG Meeting, Tele/Web Conference June 15, 2016 USNWG Meeting, Tele/Web Conference
Latest Code(s):	2020 DRAFT NIST Handbook 44 Hydrogen Gas Measuring Devices Code 2020 NIST Handbook 130 Hydrogen Method of Sale Regulation 2020 NIST Handbook 130 Hydrogen Fuel Quality Regulation and Related Definitions

Of Interest

The National Conference on Weights and Measures (NCWM) met July 14-18, 2019 in Milwaukee, WI to hold its 104^th Annual Meeting. The proposal for upgrading NIST Handbook (HB) 44 Section 3.39 Hydrogen Gas-Measuring Devices – Tentative Code to permanent status (intended to be enforced) with several modifications was adopted. The final draft of the hydrogen code is available below at: 2020 Draft NIST Handbook 44 hydrogen Gas Measuring Devices Code. The permanent code will be published in the 2020 edition of NIST HB 44.

The most significant modifications include:

Updating the code to permanent status with a January 1, 2020 enforcement date;
Updating and moving the definitions from the code into the NIST HB 44 Appendix D;
For the gravimetric test and pressure volume temperature test a reduction in the size of the required larger test draft to the lesser quantity of five times the MMQ rather than ten times the MMQ or a draft at 4 kg instead of 1 kg, whichever is larger, for paragraphs N.3. Test Drafts, N.4.2. Gravimetric Tests and N.4.3. PVT Pressure Volume Temperature Test.

The requirements left unchanged in the code are:

Recognition of the use of a master meter test standard (see paragraphs N.4.1. Master Meter (Transfer) Standard Test and N.4.1.1. Verification of Master Metering Systems;
Recognition of repeatability tests for all test draft sizes to include MMQ deliveries; and
The accuracy tolerances for all deliveries remain 5 % for equipment that is new or newly placed into commercial service or undergoing type evaluation and 7 % for equipment in actual use beyond 30 days.