How to convert gas flow
Convert actual gas flow to its nitrogen equivalent before selecting a flow range.
Single gas: actual flow ÷ conversion factor
Choose a gas and enter the actual maximum flow on the selection page. Keep the input and output units consistent.
Example: 9 SLPM of methane
The conversion factor for methane CH₄ is 0.719.
9 ÷ 0.719 ≈ 12.52 SLPM (N₂ equivalent)
Select the range using 12.52 SLPM nitrogen equivalent rather than the actual methane flow of 9 SLPM.
Reading correction: N₂-calibrated reading × conversion factor
For an instrument calibrated with nitrogen, actual gas flow = N₂-calibrated reading × C. Selection uses the inverse of this relationship.
How to calculate a mixture conversion factor
Let xᵢ be each component’s volumetric flow fraction; the fractions sum to 1.
ρᵢ is component density and Cpᵢ is specific heat at constant pressure. Use the manual’s gas-property table. xᵢ = component flow ÷ total mixture flow.
| Molecular structure | Examples | Nᵢ |
|---|---|---|
| Monatomic | Ar、He | 1.01 |
| Diatomic | CO、N₂ | 1.00 |
| Triatomic | CO₂、NO₂ | 0.94 |
| Polyatomic | NH₃、C₄H₈ | 0.88 |
Source: FL-XXX Series Manual V1.0, pp. 24–27. Standard conditions: 0°C and 101325 Pa. The quick converter covers listed single gases; contact technical support for mixtures or unlisted gases.