combustion check valve help

[singularity]

this should be the last bit of information i need to finish my new combustion mortar. in a previous thread i asked how i would vent my chamber, some of you recommended a bed inflater. well i tried it, at 40psi reverse pressure the check valve failed... so i need to make/buy a new one that can wistand combustion. are there any ghetto check valves that i could make do i have no choice but to buy a big PVC one?

[frankrede]

this should be the last bit of information i need to finish my new combustion mortar. in a previous thread i asked how i would vent my chamber, some of you recommended a bed inflater. well i tried it, at 40psi reverse pressure the check valve failed... so i need to make/buy a new one that can wistand combustion. are there any ghetto check valves that i could make do i have no choice but to buy a big PVC one?

Or buy a big brass check valve

[hi]

what do you need the check valve for anyway? between the barrel and chamber or between the vent and chamber?

[singularity]

between the vent and the chamber, there is no clean out on my particular design so i had to build a vent port into it

[hi]

why not just use a ball valve?

[singularity]

becuase the hole firing process needs to be automated (or else i will consider the project a failure)

ok i just had a really out there idea, so bear with me. a PVC check valve would cost a good deal of money and be rather bulky which would take away from the mortar look. i happen to be in possession of 5 semi working airsoft AEG gearboxes, could i use them to vent the chamber? it would most likely require the use of two small check valves (one on the nozzle the other on the cylinder) but do you think it would work?

for all of you who have never seen a AEG gearbox it uses a motor to pull back a spring loaded piston then the gear runs out of teeth and the piston it forced forward very quickly creating a burst of air which would propel the bb. you can think of it as a very small air compressor which runs off batteries.

[psycix]

Maybe create a ghetto check valve with the use of flaps coverting holes.

[Hubb]

I posted a thread the other day. It may help.

http://www.spudfiles.com/forums/viewtop ... tml#135570

[mopherman]

Why not build one? just build a spring loaded ball check valve like this.

hope this helps.

[mark.f]

Take a look at this page from Burnt Latke.

http://www.burntlatke.com/25cb-testday.html

They have a pretty good vent check system that might be of some use to you. There may be a way to contain it inside a bushing or some such so that the pressure, (although negligable), from the inflater can push the plug back.

[meatballs]

I know you've already considered this singularity, but im curious to think what other people think - do you guys think the fan from the bottom of an rc hovercraft, the one that lifts it off the ground, that forces air under the craft by sentrifugal force, do you guys think that has enough flow to vent the chamber in a few seconds?

[windshrike]

Depends. Cheap RC hovecraft or the top-of-the-line $500-for-just-the-body models that I've wanted ever since I was a lad?
I'm guessing the cheap ones and it's a maybe, upping the voltage and/or current should help it a lot.

And, meatballs, what do you mean by 'a few seconds'? 1-5, 5-10, etc......

@singularity: Go with mopherman's design, or just buy one.

EDIT: There are fairly large PVC check valves near the water pumps in Home Depot or Lowes.

[singularity]

the problem with mophermans design it it would require something like compressed air to open it. i think the only choice i will have is going with compressed air if i want to keep it small. i suppose if could get a decent sized metal chamber pump it to 300-ish psi then reg it down to like 30psi it would last a while. that way i could use a small brass check valve and eliminate the need for DWV parts (would have been used with the fan idea)