Ralphy, I predict you will be sizing an expansion chamber soon. Since
chambers only come in so many sizes, and if you are uneasy about what
the maximum static pressure at the chamber might be, you might
consider this:
maximum system static = ((vec - Delta L) * wp) / vec, where:
vec = chamber volume in cubic feet, likely 'max. acceptance' in the
data in gallons. divide the gallons by 7.48 for cubic feet.
Delta L = solution expansion in cubic feet. see NFPA 13. an example
for a 75 gal capacity of 40/60 (by weight i think) propylene glycol
between -10F and 110F would be: 75 * ((8.75/8.5)-1) = 2.2 gallons.
Divide 2.2 gallons by 7.48 for Delta L in cubic feet.
wp = max working pressure of the chamber in atmospheres (psi+14.7) /
14.7, for example (175+14.7) / 14.7 = 12.9 atmosphere.
the max static at the chamber would then be given in atmosphere, which
you would multiply times 14.7 and then subtract 14.7 for PSI.
using the above as an example, if the data shows 9 gal. max.
acceptance, your max static would be:
((1.2-.29)*12.9)/1.2=9.8 atm, times 14.7=143.8, minus 14.7 ~~ 129 PSI.
This works pretty good unless the chamber itself is also located in an
area where the temp varies wildly during the year.
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