Hybrid Safety Question

[Rob748]

Hi, I want to make a hybrid cannon, but out of PVC, Ive heard of the danger of ing polyvinlychloride, But I was pre planning, a 2inch schedule 80 or even 120. I looked at the pressure rating of a Schedule 80 2 inch chamber, and its rated clear up to 420, yet the 2.5inch chedule 80 is 470 ? kinda weird huh ?, but anyways Im not looking for a high mix, At tops 3x, I ran some numbers through HGDT, and at 2x with a 12 inch chamber the Maximum possible PSI is 220. I havent looked up the 120 schedule rating but I bet its close to 600 PSI. I know ovc has fatiqure problems and all but do you think Schedule 120 could handle up to a 3x mix with a spark strip and a chamber fan ?

Thanks

[Moonbogg]

It sounds like you are hell bent on using PVC, but have you considered aluminum pipe?

[starman]

I'll give a tentative safety OK to sched 80 or 120 at 3x hybrid mixes as long as all joints, endcaps, barrels, etc are also similarly rated. The chamber fan is much less likely to survive than in a standard 1x advanced combustion.

DO NOT fool around with a hybrid mix in a 12" PVC chamber...don't do it!!! Also don't go any higher than 3X with your other configuration.

Hybrid mixes are a whole different ballgame from air pressure (1x) mixes. You would be well advised to skip PVC altogether and go with all metal construction.

[Moonbogg]

Yeah its weird because the pressure rating of the PVC can easily handle the low hybrid mix, yet they have failed anyway. And of course when PVC fails its always explosively. I'd like to note however that my chamber fan in my large hybrid has held up great to constant 2x use and even a couple 3x shots. When I used pure O2 and mapp, thats when the fans bit the dust every time.

[MrCrowley]

Personally I wouldn't feel safe with PVC, maybe it's because i've built my own hybrid out of metal and it really scares the sh|t out of me sometimes.

I think it's better to go with some pressure rated ABS if you can find some. It can take shock and heat (or lack of) far better than PVC can and it doesn't fail so dramatically.

If this is going to be remote fired, go for it I say.

[Heimo]

When I used pure O2 and mapp, thats when the fans bit the dust every time.

I am fairly sure a metal fan would survive like this one I made a couple of days ago



it still ain't perfect so I am going to remake this fan I am still developing my metalworking skills practice makes prefect

Personally I wouldn't feel safe with PVC

my personal philosophy with any launcher is: metal all the way
I cannot understand that people trust plastic so much.

[jackssmirkingrevenge]

I am fairly sure a metal fan would survive like this one I made a couple of days ago

Looks good, did you use an existing fan as a mould and cast it?

[psycix]

Yeah nice fan.
You should make a howto.

[ramses]

Nice work! I would make sure you had some kind of enclosure like a standard computer fan to make mounting easier.

[Heimo]

I am fairly sure a metal fan would survive like this one I made a couple of days ago

Looks good, did you use an existing fan as a mould and cast it?

correct

thanks for the kind works people

If there is enough interest I will make a how to in the off topic section

and maybe someday I will cover ammo molds when I have a need to make one