Pressure
Convert inch of water column (inH₂O) to kilopascal (kPa). 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 = 0.2490889 kPa
To convert inch of water column to kilopascal, multiply the inH₂O value by 0.2490889. To go the other way, divide by 0.2490889 (or multiply by 4.014631).
| inH₂O | kPa |
|---|---|
| 1 | 0.2490889 |
| 2 | 0.4981778 |
| 5 | 1.245445 |
| 10 | 2.490889 |
| 25 | 6.227222 |
| 50 | 12.45444 |
| 100 | 24.90889 |
| 250 | 62.27222 |
| 500 | 124.5444 |
| 1000 | 249.0889 |
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 1000 kPa.
Multiply the value in inH₂O by 0.2490889 to get kPa. For example, 10 inH₂O = 2.490889 kPa.
1 inH₂O equals 0.2490889 kPa.
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.