Making piston valve coax - need to know if itll work+ schems

[Coodude26]

I am planning to make a piston valve coax piloted by a sprinkler valve, I was wondering if there were any glitches in this schematic, if so please tell me.

Also, how big should I make the hole to link the pilot chamber and the main chamber?



I should add now that the 3" endcap is the piston because they fit really well IN 4" pipe.

[MrCrowley]

You wont need an equalization hole if you don't have o-rings on the piston.

I would also recommend putting the pressure gauge through two layers of pipe, not just the chamber. I would also put the schrader in with the fill valve/pilot valve setup because judging by that diagram the piston will slam into it.

You'll also need a bumper for the piston.

A 1" barrel with a 4" chamber is massive over-kill. You could get very similar, if not the same performance with a 2" chamber and you'll save a lot of pumping time. For a 4" chamber, a 1.5" barrel would be minimum IMO.

[elitesniper]

Don't forget to make it service able, and MrC I think thats 2'' barrel.

[Coodude26]

You wont need an equalization hole if you don't have o-rings on the piston.

Hmm... I meant to ask how big I should make the hole, I guess I forgot...
How big should it be?

I would also recommend putting the pressure gauge through two layers of pipe, not just the chamber.

I can't really do that, I don't have any pipe that would fit over the 4" stuff.

I would also put the schrader in with the fill valve/pilot valve setup because judging by that diagram the piston will slam into it.

I hadn't thought of that, thanks.

You'll also need a bumper for the piston.

Is that to stop it from making too much noise?

A 1" barrel with a 4" chamber is massive over-kill. You could get very similar, if not the same performance with a 2" chamber and you'll save a lot of pumping time. For a 4" chamber, a 1.5" barrel would be minimum IMO.

oof, I guess I keep making mistakes. The barrel is supposed to say 2"...actually upon checking it, does say that. Hooray! I wasn't the one who made the mistake this time!

MERGED:

Don't forget to make it service able, and MrC I think thats 2'' barrel.

I was going to ask how to do that...how much pressure could a screw-on endcap take before leaking?

[MrCrowley]

It is too, damn that's small font...or my eyes just suck

No, the bumper is to stop the piston from destroying your cannon more or less. It has so much force when it opens, it will potentially break the fittings off what ever it slams into.

I forgot to put my bumper back in once and it broke the end cap clean off.

A decent bumper is a necessity.

How big should what be? You don't need an equalization hole, if you don't have o-rings on the piston. Which you don't. So you don't need to put a hole in your piston.

[Coodude26]

alright... sweet. what should I make the bumper out of?

MrCrowley wrote:
It is too, damn that's small font...or my eyes just suck Wink

No, it's just facebook sucks at imagehosting

[MrCrowley]

I don't know, use your imagination. Anything that will take the beating of a piston valve and absorb as much energy as possible.

Anything like foam or what not would do the trick.

[Coodude26]

hmmm...I'm thinking some caulksaver would do the trick...

[Coodude26]

But how would I put an access hole? Would a screw-cap work?

[blind909]

Just add a threaded male adapter and an endcap.

[Coodude26]

Like the ones on the back of most people's first combustions? Or do you mean "male"?