Ref.  http://www.mmdigest.com/Gallery/Tech/leakage1.html 

Interesting numbers on the graph, but even if a pouch does leak a bit,
so what?  As long as the pouch deflates completely in 1/10 of a second
or less, over the service life of the instrument, a little leakage
really doesn't matter.

If we take the worst case number from the graph for an unsealed pouch
of 14.5 cubic inches of leakage per minute and convert to seconds
(14.5/60) we get 0.242 cubic inches of leakage per second.  If we
assume that a pouch needs to operate in 1/10 of a second and we further
convert this number (0.242/10), we get about 0.024 cubic inches of
leakage per tenth second.

0.024 inch is about the thickness of seven sheets of paper.  So, if you
take that thickness and imagine a cube of air of 0.024 inches per side
you can see that even at just one cube high, you could fit a lot of
these under a typical pouch.  If the pouch only leaks 1 of these per
1/10 second, at the worst case leakage of 14.5 cubic inches per minute,
we would have plenty of room to spare.

Ray Finch
Albuquerque, New Mexico