GAS GUIDE
Helium Compression
The leak champion — its molecules escape through clearances that hold nitrogen.
Helium is the leak champion of the periodic table and one of the most expensive gases to lose. Small molecules escape through clearances that hold nitrogen, so a hermetic machine is usually the right answer even when the duty does not demand it.
The properties that drive the choice
| Molecular weight | 4.003 |
|---|---|
| Isentropic exponent k (ambient) | 1.66 |
| Hazard profile | none of note |
| Oil-free | Common; mandatory where purity is regulated |
Which families serve it
| Family | Role in this service | Envelope | |
|---|---|---|---|
| Diaphragm | The usual answer: hermetic construction for a gas too valuable to lose | 1–900 bar(g) | family page → |
| Reciprocating | Larger flows with a leak-tight specification | to 400 bar(g) | family page → |
Where the boundaries sit
- Helium is expensive — leakage is a cost line, not only a hazard, so the sealing concept is the selection
- Its high isentropic exponent heats the gas fast per stage, so stage counts run out early and large-ratio duties go to engineering review
- Small flows at high pressure are routine; large flows at high pressure are not
Materials
Standard stainless construction; the sealing concept matters far more than alloy selection.
Related reading
Running a duty point on this gas? The selector on the home page maps gas, pressures, flow and temperature to a machine family with its boundary conditions — free.
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