GAS GUIDE
Natural Gas Compression
The baseline fuel-gas duty — and the one where the gas analysis matters more than the name.
Composition varies by source and your gas analysis matters more than the name: heavier fractions change both k and condensation behaviour. mw = 17.2 is pipeline quality (approximately 90% methane) — state the actual analysis in the RFQ.
The properties that drive the choice
| Molecular weight | 17.2 |
|---|---|
| Isentropic exponent k (ambient) | 1.31 |
| Hazard profile | flammable |
| Autoignition temperature | 537 °C |
| Oil-free | Not required by the gas |
Which families serve it
| Family | Role in this service | Envelope | |
|---|---|---|---|
| Oil-injected screw | Fuel-gas and pipeline-adjacent boosting where oil contact is acceptable | to 50 bar(g) | family page → |
| Reciprocating | Higher pressure or large flow: gathering, storage and process duty | to 400 bar(g) | family page → |
| Dry screw | Large flows at moderate pressure, tolerant of liquids and swing | to 45 bar(g), differential ≤ 15 bar | family page → |
Where the boundaries sit
- Composition varies by source — heavier fractions shift both the isentropic exponent and the condensation behaviour, so the analysis belongs in the enquiry, not the word 'methane'
- Sour (H₂S-bearing) gas moves the materials question into NACE MR0175 territory; state the H₂S level
- From atmospheric suction the screw's practical ceiling is its single-stage ratio capability, not its pressure figure
Materials
Carbon steel is standard; sour (H2S-bearing) gas moves you into NACE MR0175 territory.
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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