Calculator Form
Use the inputs below to convert ppm into partial pressure with optional dry-basis moisture correction.
Example Data Table
These examples show how ppm and total pressure combine to produce gas partial pressure.
| Gas | Input ppm | Total Pressure | Basis | Moisture % | Effective ppm | Partial Pressure (Pa) |
|---|---|---|---|---|---|---|
| SO₂ | 150 | 101.325 kPa | Wet | 0 | 150 | 15.1988 |
| NH₃ | 25 | 95 kPa | Wet | 0 | 25 | 2.3750 |
| CO₂ | 800 | 101.325 kPa | Dry | 2.5 | 780 | 79.0335 |
| H₂S | 12 | 120 kPa | Dry | 1.0 | 11.88 | 1.4256 |
Formula Used
1) Convert ppm to mole fraction
Mole Fraction = ppm ÷ 1,000,000
2) Convert total pressure into a common unit
The calculator first converts total pressure into pascals for a stable base calculation.
3) Calculate partial pressure
Partial Pressure = Mole Fraction × Total Pressure
4) Optional dry-basis moisture correction
Effective Wet ppm = Dry ppm × (1 − Moisture Fraction)
This method is appropriate for dilute gas mixtures where ppm acts as a volume or mole fraction estimate.
How to Use This Calculator
- Enter the gas name for your reference.
- Type the concentration value in ppm.
- Enter the system total pressure and choose its unit.
- Select wet basis for direct ppm values, or dry basis if moisture must be removed.
- Provide moisture percent when using dry basis calculations.
- Choose your preferred output pressure unit.
- Click the calculate button to show the result above the form.
- Use the CSV or PDF buttons to save the results table.
Frequently Asked Questions
1) What does ppm mean in this calculator?
Here, ppm means parts per million by volume or mole fraction. For dilute gases, that is commonly treated as a fractional share of total gas pressure.
2) How is partial pressure calculated from ppm?
The calculator divides ppm by one million to get mole fraction. It then multiplies that fraction by total system pressure to estimate the gas partial pressure.
3) When should I use dry basis?
Use dry basis when the reported ppm excludes water vapor. The calculator reduces the dry concentration by the moisture fraction to estimate the wet-gas equivalent before pressure conversion.
4) Does temperature change the main result?
Not in this direct ppm-to-partial-pressure approach. Temperature is included for reporting context, but the core result depends on concentration fraction and total pressure.
5) Which pressure unit should I choose?
Choose the unit that matches your source pressure data or your reporting needs. The calculator internally standardizes pressure, then converts the result into your chosen output unit.
6) Is this suitable for laboratory and industrial use?
Yes, for screening, reporting, and routine calculations. For regulated compliance work, confirm whether your process uses wet or dry basis and whether a more detailed gas model is required.
7) Why does moisture lower dry-basis ppm?
Water vapor occupies part of the gas mixture. When you convert dry readings into wet-mixture values, the target gas fraction becomes smaller because moisture adds to the total gas volume.
8) What do the CSV and PDF buttons export?
They export the visible results table after calculation. This makes it easier to store, share, or attach the numerical summary to lab notes and quality reports.