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I read a lot about procedures concerning fill power test. So i decided to share some of what i've discovered with you. Everything here comes from the IDFL website or emails exchange with down garments and sleeping bags manufacturers. I sent emails to manufacturers and some of them where very cooperative some not at all. But that's not the point here.
Fill power vs Fill volume :
Many people mistaken and believe that powerfill is defined as the volume occupied by 1 oz of down. It's not true. This is the loft or the fill volume.
So let's discuss the definition of fill power : it is the volume occupied by a down sample (usually 30 gr or 1 oz) subject to a certain pressure at a certain temperature (20 Celsius) and hygrometry (65%). This pressure is due to a mass that's put down the sample. The diameter of the mass equals the diameter of the cylinder where the sample sits. We'll call the compression cylinder.
Now what's the difference between US and EU powerfill :
US 2000 norm :
- cylinder diameter : 241 mm
- -conditionning : steaming+3 to 5 days in a sreen box
- compression cylinder : non-mechanized cylonder of68,3 grams.
- Mass of the sample : 1 oz=28,4 grams.
EN norm :
- cynlinder diameter : 284mm,
- conditionning : tumble dry +2-5 days in a screen box
- compression cylinder : Lorch machine= mechanized cylinder weighing 94,25 grams,
- Mass of the sample :30 grams
Now there is no exact conversion table between those two. But there exist some approximation. The usual one is that US FP=EU FP+50. Which is quite not true.
But there is an approximate conversion table for the cylinder used. Here we suppose that the methods of conditionning is tumble drying :
For down with a FP exceeding 700 cuin, there is an approximate difference of 4,3%. if it is between 600 and 700 cuin the difference is about 2,5 % and almost 0 for low quality down.
So a 800 EU FP down is about 840 US FP down.
Since 2005-2006 : the US norm started to use the steaming conditionning which (non artificially) improve the FP by about 50 cuin. So that's why 900 FP down suddenly appeared. Actually it's still a 850 US FP from before 2006 and manufacturer tried to trick us.
That's it for today, To be continued.