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Water Column to PSI Conversion Chart & Formula

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When working on commercial gas fryers, ovens and other equipment, knowing the basics about gas pressure is key. Water column (WC) is the standard unit used to measure natural gas and propane, but there are times you might need to convert WC to pressure per square inch (PSI) or vice versa. Luckily, we can help you out! This guide includes helpful information as well as a water column to PSI conversion chart and formula.

What is Water Column?

As we mentioned in our article about natural gas pressure for restaurant equipment, WC derives from the pressure required to move one inch of water up a U-tube. The measuring U-tube has water on one side with gas connected to the other side. The water will go higher if the pressure is higher, providing you the correct measurement.

There are about 27.708 inches WC per 1 PSI. WC is typically used as measurement in residential equipment, but some low-pressure commercial equipment use this as well. In the gas distribution network and high-pressure systems exceeding 7 inches WC for natural gas or 11 inches WC for liquid propane, the unit of measurement is PSI.

So how do you convert from WC to PSI or from PSI to WC? Below is the breakdown.

Water Column to PSI Conversion Formula

To convert WC to PSI, the formula is simple. Take your WC measurement and divide it by 27.708 to get the measurement in PSI.

Formula: WC ÷ 27.708 = PSI

For example, if you divide 10 inches WC by 27.708, it converts to about 0.3609067 PSI.

Example: 10 in. WC ÷ 27.708 = 0.3609067 PSI

PSI to Water Column Conversion Formula

To convert PSI to WC, just multiply the PSI measurement by 27.708 to get the measurement in WC.

Formula: PSI x27.708 = WC

For example, if you divide 5 PSI by 27.708, it converts to about 138.54 inches WC.

Example: 5 PSI x 27.708 = 138.54 WC

Conversion Charts

Sometimes, you might not have time to punch the formulas above into a calculator or scribble it down on a piece of paper. Below is a PDF of tables that show conversions from WC to PSI and PSI to WC:

Water Column to PSI Conversion Table