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are these materials 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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are these materials safe?

Unread postAuthor: joe blogs » Mon May 11, 2009 3:33 am

hi all, ive just got a few parts from the store today and am wondering if they will do. i looked at the wall thickness and tried to get the parts that would match my project but also take the pressure. They are an assortment of different rated bits because some of the very high presure bits didnt match my ergonomics. i am making an inline combustion launcher propelled by mapp gas. here are some pics.....

This is the chamber pipe. it is 150 mm. the wall thickness is 5mm. I used this sort of pipe on my last combustion but i used right guard as a propellant not mapp gas.


Image
what it says on the side
Image

This is the barrel. it is 50mm.the wall thickness is 3mm.

Image
what it says on the side
Image

This is the 150mm to 100mm reducer. the wall thickness is 5mm. it says on the side.
KEYPLAS DWV
123.150.100
150*100mm
PVC lic 1063
as/nzs1260

Image

This is the 100 to 50mm reducer. the wall thickness 4mm. It says on the side.
iplex
upvc dwv
d07210050
123.100.50
100*50mm
as/nzs.1260
Image

and this is what the end of the cannon will look like with the barrell following through the reducer. The 150mm pipe has a bigger end which fits the reducer. is this bad?
Image

i want to get feedback from u guys because this launcher is held like a rocket launcher and therefore do not want it blowing up next to my face.
:(

[/img]
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Unread postAuthor: Cosmic Muffin » Mon May 11, 2009 3:45 am

it looks ok. it should be fine for a combustion
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PVC DWV

Unread postAuthor: Technician1002 » Mon May 11, 2009 3:46 am

This is how PVC DWV performes under pressure.
[youtube]http://www.youtube.com/watch?v=R7wnmtp_X3o[/youtube]
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Unread postAuthor: Biopyro » Mon May 11, 2009 3:52 am

I think that was fired before the glue had cured, because otherwise the joint would be pretty much the strongest part.
DWV is usually ok for combustions, but it is a risk. Personally I've never used it, but only because of circumstance.
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Unread postAuthor: ozoncqp » Mon May 11, 2009 5:34 am

the DWV in that video is what 95% of the cannons are made of in denmark. Its safe for spray and pray if you ask me. Shot well over 300 shots with mine. Sadly that gray pvc cant be glued with pvp cement. I tried 4 different brands now.
It simply cant "dissolve?" it, so screws is the only option. And it will lock tight with the rubber bands.

So that cannon doesnt explode it only breaks apart. Ive done alot of searches for exploding cannons and i think i found 1 that really did explode the rest just popped apart in the connections.

Then again no clue if the danish dwv and the US are the same.
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Unread postAuthor: psycix » Mon May 11, 2009 5:35 am

It is indeed "acceptable" for a simple combustion, but it is never safe.
For an advanced combustion, I wouldn't trust it, so no extra spark gaps, fan and metered fuel injection. A spray and pray would be "OK".
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Unread postAuthor: joe blogs » Mon May 11, 2009 6:06 am

The plan i have for this cannon is as follow's (advanced?simple?).this is all the simple stuff. i could be bothered drawing up how the cam lock seals well and how everything bolts, screw and glues together i just want to give you an idea of what im doing with this pvc and what do you think i can do (buy a new reducer?) to make it safer if it is not already safe.

Image[/img]
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Unread postAuthor: psycix » Mon May 11, 2009 6:09 am

I wrote:For an advanced combustion, I wouldn't trust it, so no extra spark gaps, fan and metered fuel injection.

Your design got all of these, being an advanced combustion. I suggest getting better pipe/fittings that does not say "DWV".
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Unread postAuthor: SubsonicSpud » Mon May 11, 2009 6:23 am

I would not use it, particularly if you want to keep you're eyesight and hearing. Fork out the extra money and get rated fittings and pipe, then you can enjoy spudgunning without the constant risk of having it blow up in you're face, or even worse someone elses. Remember it is not exactly a legal hobby in Australia (i'm guessing that is where you are by the code on the pipe) so if someone gets injured the authoritys may come looking :shock:

The pressure rated piping will have a PN number on it usually PN9 or PN12 for most sizes available in the usual hardware stores, fittings are usually PN18. The PN number is the pressure rating in Bar

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Unread postAuthor: Cosmic Muffin » Mon May 11, 2009 7:18 am

i cant find pressure rated pipe over here.
and the fittings are very expensive. 50 bucks for a 100-50 bushing!
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Unread postAuthor: SubsonicSpud » Mon May 11, 2009 7:40 am

Cosmic Muffin wrote:i cant find pressure rated pipe over here.
and the fittings are very expensive. 50 bucks for a 100-50 bushing!
All the pressure rated fittings up to about 60mm can be bought from most hardware stores. It is the bigger sizes which can be expensive. you can get all the sizes from tradlink plumbing, but it is not cheap. Best to find a small irrigation shop to help you out. Things like 100-50 bushings are going to be expensive, they are not a commonly used component. It all depends on what price you are willing to pay for greater safety. Personaly I stick to pneumatics, as large pipe sizes are not required to get high power levels and the components can be obtained from most hardwares.

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Unread postAuthor: jmadden91 » Mon May 11, 2009 8:05 am

hey mate im from aus to.
I get all my pressure stuff from Reece and Tradelink. They have all the parts but it is expensive. It cost me $35 for my 100ml x 50ml reducer. I have made a cannon out of DWV before but i would not recommend it. It was simple hairspray fueled and i used a pilot hole to ignite it lol. Iv binned it because of all the talk about how unsafe it is.
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Unread postAuthor: jimmy101 » Mon May 11, 2009 10:10 am

psycix wrote:It is indeed "acceptable" for a simple combustion, but it is never safe.
For an advanced combustion, I wouldn't trust it, so no extra spark gaps, fan and metered fuel injection. A spray and pray would be "OK".

The meter really doesn't affect the maximum operating pressure of the gun. All the meter does it lets you hit the maximum pressure consistently. A spray-n-pray will occasionally get lucky and be perfectly fueled. If the gun would fail with a meter it'll fail with spray-n-pray. It just might take many shots in spray-n-pray mode before you actually hit a stoichiometric mixture.

Your design got all of these, being an advanced combustion. I suggest getting better pipe/fittings that does not say "DWV".

Whether the pipe/fittings say "DWV" or not is totally irrelevant. What the pipe must say is "PWS" or have a pressure rating or have a specification number that puts it in a class that has a suitable pressure rating. All pressure rated pipe is also rated for DWV use and often pressure rated pipe (in the US anyway) will say both PWS and DWV.
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Unread postAuthor: Carlman » Mon May 11, 2009 10:13 am

Reece and tradelink are absolute ripoffs, as i sugested to someone recently make friends with an irrigation store owner/employee, you can get fittings for cost which is about 1/5th the price of reece and tradelink.

I would NOT use those materials to build a gun ever. DWV in aus is weaker than its american counterparts.

Take a look rond new housing estates for dumped pipe, I can get as much 4" pn12 as i like aswell as many other sizes.
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