Help with twin chamber/valve "T-shirt Launcher"

[Lasse]

Do anyone have experience of twin valve Launchers?

Im currently working on a Pneumatic launcher almost similar to the Spudgun Technology Centers compact Launcher TBL250LP which I shall use as an effect in a comedy show. We want to shoot out some cloths 40-50 feet, not more, but Im anyway considering a twin chamber model with twin valves in order to let more air through, because we would like the Launcher also to create a loud sound (blast or bang) when the Launcher is fired!

Will the double airflow from the twin chamber/valves create a blast or will it just shoot out the ammu (cloths) even further???

The valves are modded Orbit sprinkler valves 1". The barrel will be 3" wide and about 12" long because the Launcher has to be compact enough to hide in a theatrical prop.

Any experienced builders comments would be appreciated as the SGTC seems to busy to reply to incoming requests and orders for more than 8 weeks now. Therefore I now plan to build the Launcher myself.

[djt]

im not sure about being a louder bang. if you wanted that you could probably put a burst disk right before the barrel to create the noise.

http://spudtech.com/detail.asp?id=40

scroll down to more pictures and look at the third one over on the top row. use a system like this to fire both chambers at the exact same time.

[Brian the brain]

If you want a bang, go for a oversized air reservoir and a short barrel.
The short barel will keep your range down and make a loud noise,
plus the oversized reservoir makes sure there's enough volume and pressure left to make a really loud noise.

[Steve-]

wouldn't a piston valve make an even louder noise.

Edit: You prolly don't want to spend that much time making one, nvm.

[Lasse]

Yes I have also got the impression that a piston valve would do the job, but unfortunately its impossible to buy the prommising Supah valve from Spudtech because they didnt reply to any mail or voicemessages for two months now.

Lasse

[MrCrowley]

you dont have to buy the supah you can make one inferior to it but still as affective as two 1" sprinkler valves.theyre not the hardest things in the world to build just do some research if you havnt already and you should be fine.

[Shrimphead]

A 1" piston valve would probably be MORE efficient than two 1" sprinkler valves.

[Lasse]

Interresting! Ill have a look at some of the plans in the forum regarding construction of a piston valve. If its not to difficult I might give it a go.

Lasse

[nicholai]

A 1" piston valve would probably be MORE efficient than two 1" sprinkler valves.

no it wouldnt, the airflow would be restricted in comparison to a sprinkler valve. The piston valve would open a hell of a lot faster, be a lot louder, but wouldnt outperform two 1" modified sprinkler valves.

[MrCrowley]

prolly not 2 modified ones,but sprinkler valves also restrict and the opening time would be relativly the same maybe a bit faster for a sprinkler valve as there is less pilot space and its smaller

[Shrimphead]

Ok, maybe not better, but definately comparable. Sprinkler valves have tiny porting. But it would be cheaper.

[Nereth]

Im working on a gun right now with two parralel one inch modified sprinkler valves. The problem is, because they have to join up again after they split, theres both a lot of dead volume, and the gas streams are going to smash together at the Y connector and

a) blow it clean off
b) heat up
c) work, but with turbulance

I can only hope it isnt a severe waste of time. The design is supposed to counter the shit flow coefficient of the valves.

BTW, comparison to piston valves: these are two diahragm valves of very similar construction to a 1" orbit watermaster, both pneumaticly actuated through quarter inch hose, which feeds into half inchish hose and then through a super fast opening ball valve, and out to open air.

compared to a one inch piston valve, will they
a) actuate faster
b) move more air
c) perform better in general

[MrCrowley]

well if you make a 2" piston valve it will

A)be cheaper
B)more effiecent
C)better flow
D)Perform overall better

[Nereth]

yeah but what about actuation speed, and would mine have better flow than a single 1 inch piston valve?

I dont have the technical skills, nor can i be bothered, to make a piston valve.

[Shrimphead]

Diaphragm valves do open faster. But, piston valves have much larger porting. I imagine that you've seen the inside of a sprinkler valve. They choke the flow quite a bit. I guess to 1" sprinklers might do better, but still a lot more expensive.