Bill,
You have given a lot of valuable information to this forum… thanks. Hopefully my response to your questions will likewise be of value to you.
Your post stated in part, “I have no idea what the CLO valve gives me…”
I would like to first attempt to describe the insulation measurement terms:
Thermal Conductivity – This is an inherent property of a material. Thermal Conductivity differs with each substance and may depend upon on structure, density, humidity, pressure and temperature. This number is always reported for a FIXED THICKNESS and FIXED SET OF TEMPERATURES, as well as keeping the other variables fixed. W/mK (most common), (cal/sec)/(cm2 C/cm), or BTU in /hrft2F are the optional ways of expressing the thermal conductivity. You can multiply a known thermal conductivity value by the appropriate constant to easily convert to another thermal conductivity expression.
The following W/mK numbers are relevant to answer your questions:
Water at 20 C ( 68F) = .580 (This is why you don’t want it in your insulation) Climashield HL = .089 Insulators = <0.065 (Construction industry standard) Climashield XP = .043 Polarguard Delta = .041 Air at 0 C (32F) =.024 (The unmoving air is what provides the insulation, not the fiber. The more trapped air, or loft, the better)
Thermal Resistance – This number is always reported for the variable insulation THICKNESS. It is calculated from the thermal conductivity number. 1 divided by the thermal conductivity and then multiplied by the appropriate number for the variable THICKNESS. R Value, m2K/W, clo, and TOG are the optional ways of expressing thermal resistance. You can multiply by the appropriate constant to easily convert from one type of thermal resistance expression to another.
The following R value, m2K/W, and clo values are for a 1” insulation THICKNESS. For example, 2” of an insulation’s thermal resistance can be determined by multiplying the 1” value by 2 and a ½” sample can be determined by multiplying the 1” value by ½.
Water = R value of .249, m2K/W value of .044, clo value of .283 Climashield HL = R value of 1.613, m2K/W value of .284, clo value of 2.846 Insulators = > R value of 2.217, m2K/W value of .391, clo value of 2.524 Climashield XP = R value of 3.382, m2K/W value of .596, clo value of 3.850 Polarguard Delta = R value of 3.515, m2K/W value of .620, clo value of 4.001 Air at 0 C (32F) R value of 6.005, m2K/W value of 1.058, clo value of 6.836
clo/oz – We need to look up WEIGHT yd2 for the specific insulation to determine the clo/oz per yd2. This value is normally just referred to as just clo/oz with the y2 being implied. clo is an easy number to grasp its relevance because 1 clo is the insulation value of an average man’s dress suit. The Climashield XP clo/oz is calculated by taking the 1”THICKNESS clo value I previously listed as being 3.850 and dividing it by the oz yd/2 for 1” THICKNESS which is 5. Reference http://www.climashield.com/pdf/Climashield_HL_Spec_Fact_Sheet_for_CS_Our_Products.pdf for the insulation weight and thickness. 3.850 / 5 = .77. Please note that the Climashield URL reference table number for clo/oz is also .77. A great source for weight and thickness of various other types of insulations is the BPL reviews of synthetic jackets and belay parkas since they state the insulation used and the actual loft that BPL measured.
Your post also stated in part, “I have been told that the CLO for the 1.8 PG Delta is around 0.77 and not the higher number posted here sometime ago.” I was the one who posted the higher number.
I will now calculate the PG Delta clo/oz value using the same procedure I did for Climashield XP. The PG Delta clo/oz is calculated by taking the 1”THICKNESS clo value I previously listed as being 4.001 and dividing it by the oz yd/2 for 1” THICKNESS which is 2.73. This 2.73 thickness value was calculated by taking BPL PG Delta loft measurement for 3 oz/yd2 of 1.1”. See the GoLite Belay Parka measurements in http://www.backpackinglight.com/cgibin/backpackinglight/high_loft_synthetic_belay_jackets_2005_review_summary.html?print=1. The adjusted WEIGHT for 1” of insulation, if it were manufactured, would be 4.001/(1/1.1)*3 = 1.47.
To do a simple sanity check of the calculations just note that a 1” THICKNESS yd2 of Climashield WEIGHS 5 oz (Climashield URL) and a 1.1” PG Delta THICKNESS yd2 weighs 3oz (BPL URL). The PG Delta clo/oz is more than double what the Climashield value is and so the clo/oz should be more than double assuming the thermal conductivity values are the same. In fact the thermal conductivity value for PG Delta is better than Climashield. It should be no surprise to anyone that Climashield HL or XP insulated garments are not what Ryan and group will be taking to Alaska.
Bill, you stated in part, “I have been told that the CLO for the 1.8 PG Delta is around 0.77…” I calculate the PG Delta 1.8 oz clo value as 1.2. Remember 1 clo is the warmth you would get wearing a business suit. You can test this clo value subjectively if you have a Cocoon pullover. If it feels warmer than wearing a business suit, then my calculation is probably correct. If it is provides much less than the warmth of a business suit then your source is probably correct.
Richard Nisley
Edited by richard295 on 06/04/2006 16:02:05 MDT.
