Pressure
Convert millimetre of mercury (mmHg) to pound per square inch (psi). 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 = 0.01933678 psi
To convert millimetre of mercury to pound per square inch, multiply the mmHg value by 0.01933678. To go the other way, divide by 0.01933678 (or multiply by 51.71492).
| mmHg | psi |
|---|---|
| 1 | 0.01933678 |
| 2 | 0.03867356 |
| 5 | 0.09668389 |
| 10 | 0.1933678 |
| 25 | 0.4834195 |
| 50 | 0.9668389 |
| 100 | 1.933678 |
| 250 | 4.834195 |
| 500 | 9.668389 |
| 1000 | 19.33678 |
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 145.0377 psi.
Multiply the value in mmHg by 0.01933678 to get psi. For example, 10 mmHg = 0.1933678 psi.
1 mmHg equals 0.01933678 psi.
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.