"Scott Bemis" wrote in message
om...
Thanks for the tips for not create "negative pressure" in drybags,
assuming that I could find purge valves to purge the excess air from a
dry bag. I still would like to incorporate purge valves in my
homemade drybags.

End

Try a manufacturer of scuba diving drysuit valves, and use an automatic
cuff-dump valve. The Apeks ones are good, small and reliable, and easy to
install. Here is a source in theUK
http://www.divebooty.co.uk/equipment...ls.asp?pid=276 but for USA I'd
suggest trying rec.scuba.equipment and I'm sure they'll be able to help.

Cheers
David M