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Field test apparatus to evaluate hydrogen gas dispensers

Today, demonstration vehicles are refueled with hydrogen from dispensers within 3 minutes to 5 minutes using sequential gas releases from a bank of pressurized cylinders. The sequential releases generate large, rapidly-changing, gas flows (0 kg/min to 10 kg/min) spanning a wide pressure range (0 MPa to 70 MPa). Such flows are difficult to measure using off-the-shelf flow meters. To evaluate the performance of retail dispensers at the point of sale, NIST developed a field test standard that will be used by state weights and measures inspectors to periodically test retail hydrogen dispensers, much as gasoline dispensers are tested today. The dispenser includes a “master meter” that has a calibration traceable to NIST’s Transient Flow Facility— a facility designed with this application in mind.


Provide metrological tools and standards supporting the fair trade of hydrogen gas as a vehicle fuel of the future.


The Fluid Metrology Group (FMG) and the Office of Weights and Measures (OWM) collaborated in designing, constructing, and testing a hydrogen gas dispenser field test apparatus that utilizes three independent measurement methods. 1) gravimetric, 2) PVT, and 3) master meter. This project will enter a field test phase in 2014.


Demonstrate safe, affordable, low-uncertainty, methods for testing the accuracy of dispensers of hydrogen gas at working pressures up 35 MPa.

Technical Approach

NIST is using its Transient Flow Facility (TFF) as a high-pressure helium gas source to simulate type D dispenser filling of a 1 kg capacity hydrogen vehicle storage tank. The storage tank is built into a portable field test apparatus (FTA). The apparatus is equipped with temperature and pressure sensors, a Coriolis meter as the master meter, and automated data acquisition. The FTA will be evaluated such that the requirements of NIST Handbook 44: Hydrogen Gas-Measuring Devices–Tentative Code are met.

During the laboratory phase (Phase 1), we designed, constructed and tested the FTA in a controlled environment. The TFF allows us to: 1) evaluate each field test method using surrogate gases (nitrogen and helium) without the time and safety constraints that will be encountered in the field, 2) use more accurate instruments that are incompatible with high-pressure hydrogen, and 3) achieve the best possible reproducibility. The field tests (Phase 2) will be carried out at one or more retail hydrogen dispensers.

Major Accomplishments
  • FTA design and construction completed.
  • Temperature and pressure sensors calibrated and installed.
  • Data acquisition hardware installed and software complete.
  • Phase 1 tests complete.
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Field test apparatus to evaluate hydrogen gas dispensers

Portable apparatus side view showing high pressure storage tank (underneath) and the pressure measurement manifold.

Portable test apparatus (fron view) to evaluate hydrogen gas dispensers

(Click for hi-res image.) Portable apparatus front view.

Lead Organizational Unit: PML

State Departments of Weights and Measures
NIST Office of Weights and Measures
Dispenser and Flow Meter Manufacturers


Jodie Pope
301-975-4586 Telephone

John Wright
301-975-5973 Telephone

Juana Williams (Office of Weights and Measures)
301-975-3989 Telephone

100 Bureau Drive, MS 8361
Gaithersburg, MD 20899-8361