Where does our nuclear certification stand?

An operator of hydrogen refuelling stations for heavy vehicles needed a pressure regulator that could deliver stable pressure from 700 bar storage outdoors at temperatures down to −40 °C. No catalogue model met all the requirements.

We started with the D973, our high-pressure regulator, is rated for 700 bar inlet pressure with BSPP connections and 1,000 bar with 3/8" OD SFX. We still had to adapt it to low temperatures, the station's pressure cycles and hydrogen leak-tightness requirements.

The specification.

Parameter	Requirement
Fluid	Gaseous hydrogen
Inlet pressure	700 bar
Ambient temperature	Down to −40 °C, outdoor installation
Body	316L stainless steel
Leak tightness	Int. 10⁻³ · ext. 10⁻⁴ mbar·l/s, helium
Upstream filtration	10 µm

Five steps,
fourteen weeks.

1. Review the requirements with the operator and select the D973 as the starting model.
2. Adapt the materials: 316L body, PCTFE seat and seals qualified for low temperatures.
3. Machine and assemble the prototype in Andilly.
4. Test helium leak tightness, pressure cycling and cold resistance.
5. Complete site acceptance with the operator and hand over the documentation.

“Starting with a proven model let us focus on the two main changes: cold conditions and pressure cycling.”

IMF engineering team

What we learned

• Using a catalogue model as the starting point significantly shortens qualification.
• Cold conditions affect the choice of seals and seat as well as the body.
• Helium testing each component verifies hydrogen leak tightness.

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