Re: [AMC-list] quiet in here, 195.6 ohv cooling system

[ameskg@xxxxxxxxx]

Pretty sure a 15psi cap is 15psi over to open. If it was just 15psi then it may
as well be open to the atmosphere. : )

Ken

Quoting Frank Swygert <farna@xxxxxxx>:

> I found a chart for plain water. Each psi over 15 psi (atmospheric pressure)
> raises the boiling point by 3° (212°F at atmospheric pressure). BUT, anything
> added to water will increase the boiling point/decrease the freezing point.
> So the ethylene glycol has that effect too.
> 
> http://www.engineeringtoolbox.com/boiling-point-water-d_926.html
> 
> Check this Wikipedia article out! It has the boiling point vs. concentration
> of ethylene glycol (anti-freeze). Assuming that the boiling point is raised
> the same as water a 50/50 mix would boil at 225° + 3° for each psi over 15
> psi (14.7 psi).
> 
> So a 13 psi cap won't work -- I run a 16 or 17 psi cap, which only adds 3-6°.
> Somehow that doesn't sound right. I know some engine run around 250° without
> boiling over. Is a radiator cap rated at psi over atmospheric? Then a
> radiator would run 225° + 36° (261°) with a 13 psi cap and 50/50 mix... which
> sounds about right...
> 
> ---------------------
> Date: Sun, 18 Jul 2010 22:14:01 -0700
> From: tom jennings<tomj@xxxxxxx>
> 
> >
> >  " But 50/50 boils at 223F,
> >
> >  open air, or under the cap?
> >
> >
> 
> Oh right, 223F B.P. at atmospheric pressure. I can't seem to find a credible
> chart or formula for pressure vs. B.P.  but two random pages stated 48
> degrees increase in boiling point at 15psi.
> 
> So coolant is NOT boiling in the head at 230F, so that is unlikely to be a
> problem.
> 
> Still gotta find a chart or formula for this, but thanks Andrew!!
> 
> -- 
> Frank Swygert
> Publisher, "American Motors Cars"
> Magazine (AMC)
> For all AMC enthusiasts
> http://www.amc-mag.com
> (free download available!)
> 
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> 




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