The Climbing Club

at the University of Washington
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PostPosted: Sat Apr 24, 2010 12:15 am 
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UW Climber

Joined: Tue Jan 13, 2004 3:15 am
Posts: 129
The foam Therm-a-Rest Ridgerest has a published R value of 2.6 but it's made from foam about 5mm thick. Maybe it's 6mm. The foam is formed into a Z folds that undulate the length of the pad. Since it's made from 6mm foam it saves significant weight compared to a 15mm solid foam pad.

MEC publishes 15mm foam at R value of 2.06
Ridgerest 6mm Z-fold foam R value 2.6

As Obadiah and Lee posit, the real world insulation values may differ dramatically from the various published numbers, especially when considering the inflatable pads. I'm unaware if the industry has a robust standard that is rigorously followed by all manufacturers. But I am sure than my 15mm foam pad is much warmer than my friend's "ultra-lite" inflatable pad when I sat on it in the snow for 20 minutes.

REI has [recently?] chosen to adopt a European standard for measuring thermal value of sleeping bags. Some day there will be a standard for comparing pads.


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PostPosted: Sat Apr 24, 2010 12:30 pm 
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Longshanks
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Joined: Wed Jan 25, 2006 7:47 pm
Posts: 927
Location: Denver
Forget Foam! I'm going with Aerogel! 750 R*cm^2/g
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Too bad it would shatter in your pack...

Seriously though, based on David's numbers I suspect there is some funny business going on in terms of how the R-Values are measured! I'm now seriously contemplating building an apparatus to do some measurements of my own... Specifically, R-Value as a function of applied pressure would be very interesting.


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