Pressure
Convert inch of water column (inH₂O) to pascal (Pa). Pressure is force per unit area. Process engineers move constantly between SI (kPa, bar) and US (psi) units, and between absolute and gauge.
1 inH₂O = 249.0889 Pa
To convert inch of water column to pascal, multiply the inH₂O value by 249.0889. To go the other way, divide by 249.0889 (or multiply by 0.004014631).
| inH₂O | Pa |
|---|---|
| 1 | 249.0889 |
| 2 | 498.1778 |
| 5 | 1245.445 |
| 10 | 2490.889 |
| 25 | 6227.222 |
| 50 | 12454.44 |
| 100 | 24908.89 |
| 250 | 62272.22 |
| 500 | 124544.4 |
| 1000 | 249088.9 |
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 4014.631 inH₂O is 1000000 Pa.
Multiply the value in inH₂O by 249.0889 to get Pa. For example, 10 inH₂O = 2490.889 Pa.
1 inH₂O equals 249.0889 Pa.
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.