In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.

# converting inches water column to psi

Member Posts: 28
When dealing with gas preasures how do you convert inches water column to psi?

• Member Posts: 230
• Member Posts: 52
2000 International fuel gas code book....

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• Member Posts: 52
2000 International fuel gas code book...

page 106.....

27.7 in. H2O = 1 psi.
• Member Posts: 86
Roughly 28\"= 1 PSI

Best I can come up with is a mult. to convert 1 foot of water to psi. Feet of water x 0.4335= PSI. I divided .4335 by 12 (in per ft) for a mult. of .036125. So, inches of water x 0.03625 = PSI. 1 (PSI)/0.036125=27.682...roughly 28".

Larry
• Member Posts: 77
Hmmm....When in Rome

I've always used 27.8. Have read 28.8.

Guess it depends whether the code author resided in a costal place (sea level) or a mountainous place?

Just like it affects those darn gas orifices. Oh I have a story to tell over a campfire and some libations about a boiler company in Ohio and a delivery in Alberta Canada. ;-)

I live at 3500' above sea level.
• Member Posts: 45
Temp is a factor

Temperature is a factor depending upon precision needed:
1 lbf/square inch (PSI) = 27.707591 inch H2O (60 F)
1 lbf/square inch (PSI) = 27.680671 inch H2O (39.2 F)

Also, molarity:
1 foot H2O (39.2 F) = 0.974191 foot seawater

See http://www.onlineconversion.com/pressure.htm
• Member Posts: 240

Don't listen to Larry - I think he's thinkin' ounces. (Sorry, Larry....)
• Member Posts: 60
To coreysnow from joe

Your equation of 0.974191 ft/seawater only holds true for measurements taken from the North Atlantic or Adriatic Sea. You would have to make a correction factor for readings taken from the Great Salt Lake, the Dead Sea, or the Caspian Sea. The converse holds true for the brackish waters that contain less salt than the aforementioned. Pi-delta-t has to be factored into it. Or square the difference between the densities. Hopes this helps!
• Member Posts: 60
To coreysnow from joe

Your equation of 0.974191 ft/seawater only holds true for measurements taken from the North Atlantic or Adriatic Sea. You would have to make a correction factor for readings taken from the Great Salt Lake, the Dead Sea, or the Caspian Sea. The converse holds true for the brackish waters that contain less salt than the aforementioned. Pi-delta-t has to be factored into it. Or square the difference between the densities. Hopes this helps!
• Member Posts: 14

one pound of pressure will raise a column of water 27.7 inches high. We measure most residential and light commercial gas sysems in water column. Most LP systems operate at 11" wc. Most natural gas sysems work at 3.5 " wc.

Dave Flood
Director of Tech Ed
ICPA
Wallingford, Ct
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