Down testing in America.
I spoke with Blake at IDFL this morning and he told me that in the manual down loft tester, the standard used is to put a weighted “piston” on top of the down for one minute and then measure the volume. The test cylinder is 288mm in diameter and the weight is 94.25 grams.

That works out to .207786 pounds and
100.973 square inches or .701202 square feet
Divided it comes to .2963 pounds (4.74 oz) per square foot for one minute, and then presumably it is measured at that time with the weight in place.
Jimshaw I HAVE INVITED bLAKE TO JOIN THE GROUP.

From IDFL: Jeff had some things come up and didn't make it in to the office today. I've looked more closely at the calculations and also had the inventor of the manual Fill Power apparatus look at your calculations. It looks as if they are correct.

The one thing to note is that both the Automatic and the Manual Fill Power machines use the same pressure and same weight. You are correct that at the end of the one minute the measurement is taken. After the measurement is taken, the procedure is completed two additional times to ensure that the results are repeatable, and accurate.
There are a few different things that can affect the outcome such as static, and not properly mixing the down to break up clumps of down. If the analyst notices static there are set steps the analyst must take to ensure accurate results are reported.

Good luck with the post. If possible, I would be interested in viewing the forum that you are posting on, and possibly joining to hear what people are saying about Down products. Let me know what the website is, and I'll look into it.
Thanks!
Best regards,
Blake Boyer