# pvc again?



## ithurt

hey I was wondering why pvc is so dangerous for air cylinders but a lot of auto shops here seem to use it for their air distribution setups. The shop I work in is a former auto shop and there is tons of 1/2 pvc every where. . I know that some of those tools operate at a high cfm level right?

btw-I am not disagreeing with the general wisdom just curious. 

thanks


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## The_Caretaker

Shrapnel, pvc has a tendacy to explode and send sharpnel, especially in cold conditions so I have read on the forums


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## bradbaum

PVC breaks down when exposed to UV (Sun) light, this is a particular problem in haunts where we use a lot of UV black lights.

If the PVC is weakened by the UV light and the thin wall PVC pipe is used it can explode when pressurized.

I have always used steel pipe when installing permanent air lines in any of the shops I have worked in or had anything to do with.

The black ABS plastic pipe is supposed to be better for air, when it ruptures it splits and does not throw shrapnel. But I have never used it.


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## Dark Lord

I subbed out in a shop 1 time,or was going to.I saw the same plastic air line set up & i was out of there !!!! They got ins for that kinda thing even though it would still suck to get hit if it let loose,your home insurance would most likely not cover you.But would you want that on your conscious if someone got hurt from an exploding line.......especially a little ToTer......... just not worth it IMO.


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## Sickie Ickie

Cold climate plays a part too. When PVC gets cold, it gets brittle. That also limits applications to props that need PVC to hold a heavy load in cold conditions.


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## Terrormaster

Sickie, I think that answered a question I was gonna throw in. While I would never make a cylinder from PVC because of the above dangers, I was wondering about using PVC for the framework structures as opposed to aluminum? Welding is a bit out of reach for me probably for a few more years. I can't recall temps here in Connecticut dropping past the mid 30's during Halloween in the last 9 years I been here.

-TM


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## Revenant

TM I researched that when I put together my monkeyhut. Once the temp of PVC drops below about 40 it starts to lose it's shock resistance -- it may not be ready to snap but if it gets hit by something hard in freezing or near temps it gets brittle under impact.

For armatures of things that don't get banged around I still think it's hard to beat!


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## Sickie Ickie

I agree Rev. As long as the load isn't super heavy, it shouldn't be a problem. Ie. Zombies, etc.


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## ithurt

thanks guys for the replies. I understood the conventional wisdom on not using PVC. I have been seeing PVC supply lines lately.


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## Spyder

I did some research on this subject. I found there is a type of pvc that is rated for air but from what I'm told it is expensive and hard to find. It's not the normal pipe you see in HD or Lowe's. So your better off hunting on e-bay for cylinders.
Building pvc frame work Is ok, you might have to reinforce any piece of pvc that most of the pressure is on but other then that its worked for me.


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## dynoflyer

Maybe off topic but I've been using electrical conduit for framework instead of PVC, it's cheaper and no glueing, connectors, etc. I use the scraps to fabricate brackets, too. 

Hammer the end down flat and drill a hole through to secure to another piece. Need a 45or 90 degree? Just bend it. A bench vise comes in handy for smaller pieces.


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## kprimm

Also remember if you want a little more strength for pvc armatures you can use wooden dowel rods or even other pvc inside to strengthen it. I think i will always use air cylinders or even screen door closers over a pvc cylinder.


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## rottincorps

I worked at Spears manufacturing and saw some of the destructive test done on PVC. If you want to use it........Its your face and your kids hands this stuff when it breaks down from UV to the air compressor oils in the air it is cheaper to spend the extra money and do it right the first time then another trip to the hospital. besides Yul have enough problems pitching your fingers when you start to activate your new prop.....


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## Screaming Demons

Spider said:


> So your better off hunting on e-bay for cylinders.


Excellent answer. Has anyone actually read the instructions for building a PVC or screen door pneumatic cylinder? By the time you buy all the little fittings you are better off buying one on ebay. Then there is that little matter of spending hours trying to make the thing work, and it could fail at any time and hurt someone. Can't see why anyone would do that - with ebay there is just no reason for that. They aren't that cheap to make yourself.


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## billman

I saw on Makezine them making a burrito shooter (spud gun). It used compressed air and all pvc. The maker said to wrap it in duct tape.

What is the cost difference between a pvc cylinder and a real one?


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## HalloweenZombie

I have used a pvc air cylinder in the past. I tested it hundreds of times before Halloween. Halloween night came and it worked for about an hour before the cold got to it. It just stopped working. I operated it at a pressure that I felt was reasonably safe, so I wasn't going to turn up the pressure to make it work again and risk an injury. 

Another factor, besides the cold and air pressure is that pvc was designed to hold (water) pressure as a stationary construction material. It wasn't designed to be a moving part. 

The fact of the matter is that I haven't heard of anyone getting hurt using pvc cylinders, but I wouldn't want to be the first to take out a TOT.


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## joker

HalloweenZombie said:


> The fact of the matter is that I haven't heard of anyone getting hurt using pvc cylinders, but I wouldn't want to be the first to take out a TOT.


Check out this info on the OSHA website. It's not in regards to a PVC cylinder, but is related as in using PVC with compressed air.
http://www.osha.gov/dts/hib/hib_data/hib19880520.html


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## HalloweenZombie

joker said:


> Check out this info on the OSHA website. It's not in regards to a PVC cylinder, but is related as in using PVC with compressed air.
> http://www.osha.gov/dts/hib/hib_data/hib19880520.html


That's great info. Finally, some fact to back up the theory.


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## Wicked Saw 2 Cut

*abs*

I may be going out on a limb here. Back on a forum I was on a few years ago. There was a large, long discussion on PVC and ABS. I no longer have the info or the URL,s to the information, but it was concluded that nether is safe. I am not here to tell anyone what to use, but I will tell you that, "HDPE" pipe is the "only pipe" that ruptures and splits giving off no shrapnel. ABS is just as dangerous as PVC. HDPE is the only plastic pipe certified for use in the pyrotechnics industry for use as mortars. A shell going off in a tube will cause a blow out at the point of explosion, but it will be a tear or rupture with no flying sharp Pieces.

The problem you have with HDPE is, there is no way to join it except for very expensive plastic wielding equipment. The reason it can be used for mortars is, you are only plugging one end with a pressed in wood plug. Then the pipe is drilled and screws or nails driven in to the plug. I have only heard of one accident with PVC or ABS cylinders and that was years ago. If you really want to find info on how dangerous it is under high pressure goggle it, or look up some of the pyrotech forums, and just mention PVC or ABS. Just do not tell them I sent you and be ready to be ripper.


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## redg8r

Wicked Saw 2 Cut said:


> I have only heard of one accident with PVC or ABS cylinders and that was years ago.


I've witnessed an explosion in a shop where PVC was used to deliver @90 psi thru the shop.

While working, it simply exploded a few feet from the compressor and sent shrapnel 75 yards into the parking lot. these were not small pieces either, some were over a foot long and all the pieces were shaped like small javelins :xbones:

Myself like many others have used pvc, but I've switched to door closers (debate ably safer) but agree that getting a true air cylinder is not much more expensive. JMO.


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