Synthetic Quilt Temperature Rating Question
Posted: 17 December 2009 10:30 PM   [ Ignore ]  
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I have some materials on-hand and I’m considering using them to make a synthetic quilt. Before I start construction, I have a few questions:

1.) Which temperature rating do you think is more accurate for this quilt?

2.) From a weight perspective, is it worth trying to replace a 15 degree down mummy bag weighing ~2lbs. 15oz. by making a quilt from the materials below? I would probably need to use more then two layers of insulation to reach 15 degrees.

3.) If the answer to #2 is no, perhaps this quilt could be used as my warm weather quilt. Or, the materials could be used to make an insulated jacket and pants.


MATERIALS
—————-
Shell: Thru-hiker.com 1.1 oz Nylon Ripstop 1st Quality

Insulation:
2 layers of Thru-hiker.com Climashield Combat
Per layer: 3.7 oz/sq yd. loft =.9 ” nominal. clo=.78/oz.
Total CLO: 3.7 * 0.78 * 2 layers = 5.77


EXPECTED TEMPERATURE RATING
——————————————-
100 – ( 40 * T )
100 - (40 * 1.8) = 28 degrees F

In this formula, the letter “T” represents the thickness, in inches, of that part of the quilt or bag covering you. Source: page 22 at http://www.rayjardine.com/ray-way/Quilt-Kit/index.htm or page 82 of Trail Life by Ray Jardine.

“Thirty-two degrees F, or 0 degrees C, you’d need a CLO value of 6.”
Source: http://www.adventurenetwork.com/cgi-bin/adventurenetwork/HTB-StayingWarm-Science.html

Based on that CLO information, the temperature rating for this quilt would be slightly above 32 degrees F.

Thanks for your help,

Nick

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Posted: 18 December 2009 09:18 AM   [ Ignore ]   [ # 1 ]  
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There are many posts here with more information on clo that you can find with a search of the forum. 

In general, the US temperature rating is a ‘low limit’, not a ‘comfort’ rating.

The direct measurement of loft equation you reference is outdated but functional.  Insulations vary in their thermal resistance, so the thermal resistance of an inch of one type of insulation may not be the same as another type.  Directly comparing loft with a ruler is easy and gives the best results working within a single type of insulation, such as comparing the loft of two XP bags.  Ruler comparisons of loft give poor results when comparing different types of insulation, such as a Primaloft and a Climashield or even different types of one class of insulation, such as the continuous filament insulations 3D and XP.  Clo values give the best way of comparing the thermal resistance of different insulations.

So much of temperature ratings depends upon the design of the item and the metabolism of the person.  The best results are obtained by making (or buying) an item and then using the 1st person feedback from its use along with the clo ratings to refine future predictions.

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Posted: 07 February 2010 11:29 PM   [ Ignore ]   [ # 2 ]  
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I made an identical quilt to the one you’ve described.  1.1 Ripstop on the outside, Momentum Taffeta on the inside and 2 layers of Combat.  I used the quilt last October in the mountains of WV and the temp was about 32.  I got cold with clothes on.  I would say that 40 is the lower range for this setup, unless you are a really warm sleeper.  My quilt weighs 1lb 9oz.

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