Pressure
Convert millimetre of mercury (mmHg) to standard atmosphere (atm). Pressure is force per unit area. Process engineers move constantly between SI (kPa, bar) and US (psi) units, and between absolute and gauge.
1 mmHg = 0.00131579 atm
To convert millimetre of mercury to standard atmosphere, multiply the mmHg value by 0.00131579. To go the other way, divide by 0.00131579 (or multiply by 759.9999).
| mmHg | atm |
|---|---|
| 1 | 0.00131579 |
| 2 | 0.002631579 |
| 5 | 0.006578948 |
| 10 | 0.0131579 |
| 25 | 0.03289474 |
| 50 | 0.06578948 |
| 100 | 0.131579 |
| 250 | 0.3289474 |
| 500 | 0.6578948 |
| 1000 | 1.31579 |
Line and vessel ratings, pump discharge heads, and relief set points are all specified in pressure units — usually psi or barg in the field and kPa in calculations.
Always track whether a value is absolute or gauge: 0 barg equals about 101.3 kPa absolute, and mixing the two is a common and costly error.
Worked example. A pressure of 7500.616 mmHg is 9.869233 atm.
Multiply the value in mmHg by 0.00131579 to get atm. For example, 10 mmHg = 0.0131579 atm.
1 mmHg equals 0.00131579 atm.
Line and vessel ratings, pump discharge heads, and relief set points are all specified in pressure units — usually psi or barg in the field and kPa in calculations.