GAS GUIDE
Hydrogen Compression
The smallest molecule in the plant sets the hardest rules.
Hydrogen is refractory to any version of hydrogen compatibility being handled in any other way than through austenitic stainless or aluminium. Its autoignition temperature is only 560 °C and it ignites from a much lower energy spark than hydrocarbons — ATEX classification must be derived from the actual zone, never assumed.
The properties that drive the choice
| Molecular weight | 2.016 |
|---|---|
| Isentropic exponent k (ambient) | 1.41 |
| Hazard profile | flammable |
| Autoignition temperature | 560 °C |
| Oil-free | Common; mandatory where purity is regulated |
| Special mechanism | Hydrogen embrittlement of susceptible steels |
Which families serve it
| Family | Role in this service | Envelope | |
|---|---|---|---|
| Diaphragm | Purity-critical and high-pressure duty: refuelling, storage, specialty filling | 1–900 bar(g), to 1,000 Nm³/h | family page → |
| Reciprocating | Large flow at high pressure: pipeline and process hydrogen | to 400 bar(g), very large flows | family page → |
| Dry screw | Low-pressure hydrogen at very large flow | to 45 bar(g), differential ≤ 15 bar | family page → |
Where the boundaries sit
- Hydrogen embrittles many steels — wetted materials need an explicit hydrogen-service statement, not a datasheet default
- Hydrogen-rich service carries a tighter discharge-temperature limit in the compressor standards than the general one
- Above 900 bar(g), with droplets in the gas, or with flow quoted in actual m³/h, the duty goes to engineering review
Materials
No high-strength steels (no 13Cr, no quenched-and-tempered bolting above hardness limits): NACE MR0175 / ISO 15156 for sour service, plus an explicit hydrogen-service material statement from the vendor.
Related reading
- High-Pressure Hydrogen Compression: The Pressure Ladder, the Sealing Breakthrough, and Where the Grades Now Stand
- Reciprocating or Diaphragm for High-Pressure Hydrogen?
- Hydrogen Compression Reliability: Where the Downtime Actually Comes From
- Compressing Green Hydrogen: The Pressure the Electrolyser Does Not Deliver
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