OK MR CAPS LOCK. 
I was not saying that your idea was bad - i was suggesting that often valves and seals are only rated in one direction. IE a central heating system is rated from 10 bar from inside the pipe. If your reverse the pressure gradient the seal MAY fail depending on the spring in relation to the o-ring, but i am not a plumber. I do not know the technical aspects of the valve, hence my use of may and not will in my original post.
Possibly i could have written my query a little better, but there is no reason to be a caps lock about it. Hmm or am i being over sensitive? see here:
http://www.yourhtmlsource.com/starthere/netiquette.html
I hope they do work though. Assuming they are marine grade stainless steel and not too heavy. Oh, and not two different metals that will electrolise, cake and jam up on contact with salt water should you want to dive outside of a quarry. 
{Edited by moderator - a few letters inserted to reduce insult}