But, I guess I just didn't hit the "post" buttong, so here it is now:
imaseoulman, could you explain your concept? It sounds interesting.
Back pressure valves are a form of check valve. I'll make a guess that you're going to manually push/pull the check to open the valve. That should work. I've actually thought of this before but never did anything with it so this was the first thing to come to mind. The problem with this is finding a reliable way to push the check.
No, it's a back pressure valve and functions almost identically to a Big Salvo blast chamber. If I pushed or pulled the seal to open it, it would not be a back pressure valve, would it? The only thing that took the slightest amount of creativity was thinking up parts that would work, were cheap, and how to deliver enough air fast enough to create a seal. I have several designs ranging in price from $5 to $15 with my first prototype probably costing $12. The whole thing is an exercise in obtaining maximum flow rate. We'll see how it goes.