R-Value testing

which sleeping pad?  Maybe it’s already been tested

Roger has a setup for testing sleeping pads.  Richard Nisely also I think.

. APPARATUS FOR TESTING THERMAL INSULATION PROPERTIES .

here are a few STANDARDIZED R VALUE DATA but I don’t know which pad you are looking for in particular?

The best way I have found to test the Rvalue of a sleeping pad is to put it on ice and snow in subzero temps (with or without a tent) and see how it works.  This is a no-nonsense test and you’ll know the results for sure by morning.

One of the reasons down is such a good insulator is that all the tiny barbules in a down plumule have a lot of surface area for what is known as “boundary air”.

A small amount of air is attracted to the surface of certain substances forming a boundary only molecules thick. This boundary air tends to stay in place better than air next to it and it may be due to electrostatic charge. this layer of air is much like “dead” air, not moving and not involved directly in convection and heat loss.

This may be why synthetic insulation manufacturers mix thicker fibers for loft retention with finer fibers for more boundary air as well as fill for the loft.

I forget What is the conversion factor from Imperial/US :”R” values to metric?? 0.6??

The SI unit for R-value is kelvin square meters per watt (K·m2/W).

The imperial unit for R-value is degree Fahrenheit square feet hours per Btu, (ft2·°F·h/Btu).

The conversion factor is 1 ft2·°F·h/Btu ≈ 0.1761 K·m2/W,

or 1 K·m2/W ≈ 5.67446 ft2·°F·h/Btu.

Great, thanks all for the information (especially the article, should have searched it!).

The pad is a new pad that I’m making and the factory quoted 3.4 R-value and after the icy night test (…) I don’t think that is true. I’ll try and do the test, thanks.

Around freezing, put a 7-10mm closed cell foam pad on TOP of the air mat and it will be warm.

You have already tested without a lab!