Printech Archives, March 1997: Re: fountain solution alternatives to IPA

Re: fountain solution alternatives to IPA

Robert Gifford (
gifford@epd.engr.wisc.edu)
Fri, 21 Mar 1997 18:05:42 -0600



Rick Hartwig wrote:
>
> The vapor pressure seemed pretty high if I read it right. 17.4 or something.
>
> Anything with a lower vapor pressure?

The vapor pressure of the chemical Jeff Adrian described was in mm Hg.
A vapor pressure of 17.4 mm of mercury (Hg) is considered to be low.
Normal atmospheric pressure at sea level is 760 mm or 29.92 inches Hg.
If the units were inches Hg, it would be a rapidly volatilizing liquid.
This could not be 17.4 pounds per square inch (PSI) since atmospheric
pressure is around 14.7 PSI.

Vapor pressure measures the force exerted by molecules of the substance
which are in the vapor phase at a particular temperature and pressure.
Low vapor pressures (near 0) mean that molecules are vaporizing at a
slow rate producing few above the liquid surface which exert a low
pressure. A vapor pressure equal to atmospheric pressure means that
molecules are leaving the liquid phase in a boil, the fastest rate.

Bob Gifford,
meteorologist by education.


 

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