Conversions
Controls Unit Conversion Reference
The conversions that come up constantly in controls and water work: pressure, flow, level, power, and temperature.
Source of these values
Standard unit conversions. Values rounded for practical use.
| From | To | Multiply by | Notes |
|---|---|---|---|
| psi | feet of water | 2.3067 | For water at standard conditions. Divide by specific gravity for other fluids. |
| feet of water | psi | 0.4335 | |
| psi | bar | 0.06895 | |
| bar | psi | 14.504 | |
| psi | kPa | 6.8948 | |
| inches of water column | psi | 0.03613 | Common on low differential pressure ranges |
| gpm | MGD | 0.00144 | |
| MGD | gpm | 694.44 | |
| gpm | cfs | 0.002228 | |
| cfs | gpm | 448.83 | |
| gpm | L/s | 0.06309 | |
| L/s | gpm | 15.850 | |
| gpm | m3/h | 0.2271 | |
| m3/h | gpm | 4.4029 | |
| cubic feet | US gallons | 7.4805 | |
| US gallons | cubic feet | 0.13368 | |
| US gallons | litres | 3.7854 | |
| US gallons | pounds of water | 8.34 | The constant behind the pounds formula |
| horsepower | kilowatts | 0.7457 | |
| kilowatts | horsepower | 1.3410 | |
| degrees C | degrees F | x 1.8 then + 32 | |
| degrees F | degrees C | - 32 then / 1.8 | |
| feet | metres | 0.3048 | |
| inches | millimetres | 25.4 |
In short
The conversions used most often in water and wastewater controls: 1 psi is 2.31 feet of water, 1 million gallons per day is 694.4 gallons per minute, 1 cubic foot is 7.48 gallons, 1 horsepower is 0.746 kilowatts, and 1 bar is 14.5 psi.
Notes and limits
- The 2.31 feet per psi figure assumes water at standard conditions. Divide by specific gravity for another fluid.
- US gallons throughout. An imperial gallon is about 1.2 US gallons, and mixing the two produces a 20% error.
Direct contact
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