SpudFiles

Most likely stupid. It was an idea had while falling asleep last night.

Anyway, I can't explain it much better than the picture does.

There is a tube, and inside is a check valve type of thing that moves back and forth like a piston. Pressure is applied from behind it (check valve is configured so that it's closed from behind) and this piston moves forward. It continues to do so until the "flapper" is pushed up against the barrel, at which point (if I'm not completely missing something, which I most likely am) it opens and all the air from behind the check valve is free to now move out the barrel.

I'm not sure whether the pressure pushing on the piston will be enough to crack open the seal when it pushes against the barrel. Say 50 pounds of pressure sit behind the piston. Would it take more than 50 pounds than to crack the seal, or less because it's a smaller area? I'm having trouble trying to understand what would happen.

I'm sure that if it did work, it would have horrible performance, however it would be fairly easy to make. (PVC extension couplings and a swing check valve) That's the only reason I bothered posting it.

Your asking to much of your design.

Poor flow, even if it did somehow work.

What's the advantage over a normal piston?

MrCrowley wrote:Poor flow, even if it did somehow work.

What's the advantage over a normal piston?

Absolutely nothing! I was just trying to keep my mind busy.

I think its a pretty respectable idea , its almost like a combination of a piston, and diaphragm valve plus a burst disk. eh? as for your questions this mostly depends on what kind of disk/flap/diphram your going to use. as for ease of funtion and less complication i would recommend somthing that shatters or is disposable like alu. foil. You were saying above about a "flapper" of some sort. for one it would have to be rigid enough to not be suctioned against the barrel. also youd have to figure out a way to cock it or hold it in place till the pressure rises high enough to shoot it.

Good idea overall man , keep thinking about it and try designing a simple prototype. cheers!

PVC Arsenal 17 wrote:

MrCrowley wrote:Poor flow, even if it did somehow work.

What's the advantage over a normal piston?

Absolutely nothing! I was just trying to keep my mind busy.

Fair enough, as long as you keep your mind going over things like this.

One day you might get lucky, like how JSR gets lucky every morning he wakes up and posts another way to achieve semi-auto.

thats actually a good idea......... check valves are realy just hammer valves.........

i think this might give you a cool "pulsed" automatic thing if you put a spring to make it return to the back and gave it a low enough flow. actually, i might try this.......

Yep, Nobel Prize winner Linus Pauling said "In order to have good ideas, you must first have lots of ideas." I like brainstorming. Ideas start to mutate and breed and first thing you know, something decent comes of it. Maybe even a winner.

I think the problem is that you'd need that piston to take off down the cylinder all of a sudden in order to knock the door open, otherwise it would suction the door to the barrel like a normal barrel sealer. But if you have something to release the piston once it's already under pressure, you've gone and made it something that could be a valve all by itself.

I have a few suggestions:

1.) Make the barrel eccentric to the chamber. You could probably use a solid (socket weld) plug, with a hole the OD of the pipe you're using drilled in the plug.

2.) make the diaphragm supported by a solid disk, so it doesn't flex and maintain the seal on the back of the barrel.

Problem: The air pressure on your flap is pushing equally all over it. The flap hangs vertical and your barrel end is also vertical. The pressure will just seal the flap onto the barrel (no suction involved).

The way round it would be to increase the size of the piston face to larger than that of the check valve plate, and try cutting the barrel end to 45° (with the longer side at the top in your drawing) . This means the force on the piston is larger than that on the check valve so it should open. and the cut should help with the flow.

MrCrowley wrote:One day you might get lucky, like how JSR gets lucky every morning he wakes up and posts another way to achieve semi-auto.

It's a bit like evolution in nature - if there's a problem, throw as many different potential solutions at it as possible, one of them is bound to work