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2 liter chamber is safe?

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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2 liter chamber is safe?

Unread postAuthor: CannonBall » Tue Mar 20, 2007 5:25 pm

Hi im new here my name is patrick and im dutch..
Im going to build a spudgun(not my first) but its gone be a lot bigger. :lol:
My question.. i want to make a chamber with a volume of 2 liter or more (double walled) probably 1 cm thick in total.
with a 50 mm barrel i gues its 2 inches? correct me if i am wrong!
Or should i use a 40 mm Barrel?

Is a 2 liter chamber safe enough? (pvc)
Im going to use butane as proppelend
from a Lighter refiller

Cheerzz Patrick
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Unread postAuthor: noname » Tue Mar 20, 2007 8:02 pm

Why would PVC not be safe, especially at a set volume?
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Unread postAuthor: hi » Tue Mar 20, 2007 8:37 pm

If its sch40 pvc, then you could have the chamber be 50 liters if you wanted to. It would be a pain to fuel, but you could. Infact, i recommend that you use propane, it is more powerful, cleaner, and it dosnt smell.

To answer your question- Yes, if it is pvc and you use both primer and pvc glue, it will be safe. If you are lauching potatos, then go with the 40 mm. 50 mm will fit potatos, but 40 mm id easyer to handle.
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Unread postAuthor: deusXmachina » Tue Mar 20, 2007 8:51 pm

Hahah for a second I thought he was talking about 2-liter bottles (which work perfectly fine for minis).

The volume of the chamber doesn't matter, the best indicator of safety is the Schedule number, generally 40, 80, sometimes 120. It is based vaguely off of radius and thickness; the greater the radius of pipe, the less structurally sound it is, so they have to increase the thickness accordingly. Sch numbers give you a pretty even range of pressure ratings, however they do still drop with radius. 4" sch40 can handle up to 130 psi.

http://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html

EDIT

WOW I thought I was still in pneumatics lolzorz....umm yeah combustions usually have a spike in pressure rather than constant pressure, but schedule 40 up to 4 or even 6 inches works fine. As long as the joints are solvent welded properly, you should have no trouble.
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Unread postAuthor: rna_duelers » Tue Mar 20, 2007 9:24 pm

Metric system :wink: No schedule ratings.Pressure Number classes is what we have.

It depends on what type of PVC you use they come in classes with a Pressure Number 9 to 18 and the numbers stand for Pressure rating in Bar(14.7psi)And the pressure rated pipes have a burst pressure of 3 times there rating pressure.

When I was in Holland a few years ago I built a Spudgun for my cousins and we just used DWV pipe(not pressure rated) with a 100mm chamber and 50mm barrel it worked great.

A 2 liter chamber would be great wiht C:B ratio (chamber-barrel)There is a good ratio that people seem to stick to with usual combustions a C:B of 1.5:1 in other words 1.5L chamber and 1L barrel in volume.

As for the fuel butane fuel is often hard to get a good mix.I might sugest a cheap deodorant spray.

Good luck with the build,just PM me if you need any help.
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Unread postAuthor: CannonBall » Wed Mar 21, 2007 9:20 am

Hmm our pvc pipes in holland dont have a schedule.
Does any one know were i can see the rating?
Cause i can't see a rating on the pipe.
.

Cheerzz Patrick
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Unread postAuthor: Bubba05 » Wed Mar 21, 2007 9:37 am

Over here in australia we get PVC in normal or hi pressure gadges. ive had no dramas with the hi pressure witch is said to handle up to 25psi according to the print on the components i bort and my mate that works at the hardware store. Normal PVC can pop!! witch can hurt a bit. but in that instance my mates where being stupid and wedged stuff down the barrel that just wasent gunna cum out. as long as u dont do that u should be fine hey..
2lt mite be a bit big to fuel up quickly but hey thing of the sweet big bang ur gunna get and the fact what ever u put down the barrel is going to be long gorn!!

Bubba
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Unread postAuthor: CannonBall » Wed Mar 21, 2007 1:07 pm

Does any one know? what has to stand on a presure rated PVC PiPe in the Netherlands..
So then I can search for the right pvc.
or would u guys think unrated pvc is fine to>?.
cause my biggest spud gun had a 1600cc camber, and the barrel was 1200.
But yeah ...over 2 liter is quite big.

Greets 8)
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Unread postAuthor: CannonBall » Tue Mar 27, 2007 5:30 pm

Just calculated the distance that it shot with google earth aprox 400 feet to 450.
with hairspray as fuel.
quite inpressive i think.

Is 450 feet a good range?

cheers
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Unread postAuthor: Bubba05 » Wed Mar 28, 2007 2:53 am

thats a great result off hair spray!!!!
ramp it up now go for a higher combustable like deoderand or carby cleaner then see how u go!!

Bubba
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Unread postAuthor: FiveseveN » Wed Mar 28, 2007 4:23 am

Just thought it was worth mentioning: I once used a 5L PET bottle as a chamber, with butane. Big chambers work much better with chamber fans, but it actually worked just fine.
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Unread postAuthor: Affliction » Wed Mar 28, 2007 10:44 pm

You're building a big boy now aren't ya? My chamber is 2284 cc! 2 litre is huge and will give alot of power so material selection is important.
If you can get pressure rated ABS then use that; PVC produces shrapnel!
you may see imprinted on the pipe "sch40" this is a good pipe to use as it is pressure rated. Just a bit of advise from a Canadian!
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Last edited by Affliction on Wed Mar 28, 2007 11:09 pm, edited 1 time in total.
You are a pathetic imbecile if your spudgun goes "FWOOOMP" as you fire it.
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Unread postAuthor: MrCrowley » Wed Mar 28, 2007 11:08 pm

Why does it matter if PVC schrapnels or not? If you buy the pressure rated stuff and use it within its limits your safe. Sch40 is a thickness rating not pressure rating...it means nothing in terms of PSI....you need pressure rated pipe not only sch40/sch80 etc.
Pressure rated ABS is extremely hard and rare to get, just stick with PVC unless you have one huge supply of Pressure Rated ABS and fittings.
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Unread postAuthor: Affliction » Wed Mar 28, 2007 11:18 pm

In northern climates like Canada ABS is more common than PVC because of the potential of frozen pipes. PVC will shatter but ABS is resillant to expansion loads. And can take shock loading better than PVC.
You wan't a big cannon please shy away from pvc. I'ts just not safe.
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You are a pathetic imbecile if your spudgun goes "FWOOOMP" as you fire it.
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Unread postAuthor: Bubba05 » Wed Mar 28, 2007 11:40 pm

Ive seen sone huge ass cannons made from pressure rated PVC its perfectly safe as long as u dont do anything stupid. Yes PVC will shatter if its pushed beyond the limits of what it can handle. if ur gunna be puting 80 psi through pipe thats only designed for 40 its gunna blow. Old mate here is building his first cannon he's gorn for a big chamber im sure its a basic gun thats not gunna be produsing huge amouts of pressure. so its safe for for what he's doing Ive made 5 cannons now and ive only had one blow up and it did so coz my brother in laws mates are missing half a brain and wedged a bottle down it and used paper to seal it. barrel wasent lubricated and paper dosent slide on PVC all that well so the chamber went BOOM. It happened i smaked em in the back of the head and life goes on. CannonBall if ur real stressed about it going caterstoffic wrap ur chamber with 100 mile an hour tape (tape that has fiber glass webbing in it) or duct tape so that if it dose blow up the shapnell will be contained and u wont get all that hurt. and were anti flash gloves fo your hand dosent get burnt.

Bubba
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