Hi,
I harvested some down from old quilts, and I would like to measure the fill power.
I could not measure like the original method, but I figured out something, please check if Iam wrong (or any other measuring methods are welcome).
As I know the method is:
"taken of one-ounce sample of down in a plexiglas cylinder with a weighted piston compressing the down"
"US 2000 norm: cylinder diameter: 241 mm
compression cylinder: 68,3 grams
Mass of the sample: 1 oz = 28,4 grams"
This is clear I guess, I saw two videos about this.
My problem, I can not get this size of measurement cylinder.
I think about it and I can get cheap PVC tube from the local store with inner diameter of 105mm.
May I get same result If I downscale the method based on the section area?
I guess the base is the same pressure of the down at each method.
P=F/A
F_original/A_original=F_my/A_my
A_original=241^2*pi/4@=45593,5mm2
A_my=8654,6mm2
So the weight of compression cylinder is:
F_my=F_original*A_my/A_original
F_my=68,3g*8654,6mm2/45593,5mm2=12,96=13g
And the sample weight of down also must be scale down.
I guess if the density of down is constant and the height is still cinstant, the modified weight of sample is the ratio of cross section areas:
m_original/A_original=m_my/A_my
m_my=m_original*A_my/A_original
m_my=28,4g*8654,6mm2/45593,5mm2= 5,4g
When I put the sample weight of down in the tube and the compression weight to the top of the down, the down will compressed.
The FP will be the height of the compressed down.
CUIN is cubic inch= Area*Height
1in^3=25,4mm^3=16 387,1mm3
In the original measurement cylinder, 1 CUIN FP is equal of the height of 1in of compressed down:
H=16387,1/A_original=0,359416671mm
.. so 100CUIN FP=35,9mm
200CUIN FP=71,9mm
..and so on
If I am right, In my downscaled measurement this height is still the same as the original, because I scale down the diameter and the amount of the down also.
Am I right or wrong?
Thank you
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