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.
The proposal and background discussions 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, will be voted on for adoption July 14-18, 2019 at the 2019 NCWM Annual Meeting in Milwaukee, WI. The final draft of the proposed code and background discussions are: 1) available by clicking on JUL2019 NCWM S&T CMTE PROPOSED NIST HB 44 H2 PERMANENT CODE WITH MODIFICATIONS ; or on the NCWM website under the Specifications and Tolerances Committee Report available at: http://www.ncwm.net/meetings/annual/publication-16. Proposed modifications to the HB 44 Section 3.39 include:
- Updating the code to permanent status with a January 1, 2020 enforcement date;
- Citing the specific applicable fuel quality standard, i.e., SAE J2719 H2 Fuel Quality for Fuel Cell Vehicles;
- Reducing 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;
- Limiting the test draft size for repeatability tests to not less than 1000 indicated divisions of the device under test;
- Recognition of the use of a master meter test standard to verify a dispenser’s accuracy is eliminated from the code;
- A new performance tolerance to widen the allowable error for deliveries at the MMQ (typically 500 grams) to ± 14 percent; and
- Updating and moving the definitions from the code into the NIST HB 44 Appendix D.