Just an FYI for those guys discussing the restriction in the biopack center section.
The BMR 500 center section I have does not at first appear to have a restriction, there is no half moon at all, it is a full circle just over 1 1/4" ID, that is until one puts the scrubber into the center section, and then you get the half moon effect as when the scrubber is seated properly it blocks (rough eyeball measurement) one half of the exhale tube. The O-ring is above the exhale tube and the center section is machined such that the scrubber can go in to a predetermined depth.
There are some people (Phi, please don't get upset
) who have dove the BMR in the 300 to 400 fsw range and I have not heard of any reports of problems with WOB.
I have heard of a number of people doing sub 150 fsw dives on biopak center sections and have not heard of problems (not to say there weren't any).
Just my 2 cents.
Marc