SpudFiles

Hey guys,
I just went to our local supply store and asked about using pvc for a pneumatic potato cannon and they strongly advised me to not use PVC because it tends to have a "whipping action" when air pressure is suddenly dropped. This whipping action causes shattering of the pipe where the pipe is rigidly restrained because the PVC lacks flexibility. I have a copy of the PVC manufacturers warning page where it explicitly states " Use of compressed air or gas in PVC/CPVC pipe and fittings can cause explosive failures resulting in system damage, severe bodily injury, or death." As an alternative, they recommended using steel which is extremely heavy and double the cost of PVC. Also, the pressure rating you see on PVC pipes is for hydrostatic (water) pressure only because compressed air releases too much stored energy too fast. Should I go with steel or PVC??? Thanks

never heard of the whipping thing before
but my guns make a loud whip like crack when they are fired
take a look around, eveyones is using pvc, as long as it is pressure rated you will be fine.

The reason that pvc companies advise against air is because if there is a failure, the pvc shards will go flying everywhere unlike a water pressure failure. But, as long as you put less pressure in the pipe than it is rated for you should be fine.

Go with the PVC, i have had air cannons for 3 years, THE same pipe and havent had a problem, and if you have a little fear wrap the thing in ducttape.

WOW!! wrote:if you have a little fear wrap the thing in ducttape.

won't help, you gotta wrap it in some sort of chicken wire screen.

It sounds to me like they are just trying to make you pay more cash. Imagine how heavy a steel cannon would be. They have to say things like that so don't worry.

^ no I think it's just so they can't be sued

Of course they would advise you not to because they don't want you to come and sue them for a potato cannon blowing up and killing you. PVC will be fine just get pressure rated stuff and don't use it for a pnuematic if you want to go like above 100 psi.

I was reading this thing and it says it will do that, BUT the PSI has to be at least 20-30PSI from the max for it to do that, and who is giong to put 4in PVC up to 230PSI

REPLY:

I see, your looking for a strong pvc pipe to make the potato cannon right?? i suggest you to look and buy the pvc the color orange and choose the 1000 sries(you will see that in part of the pvc)..or you could look for the good quality of pvc on this site..http://waterdocsonline.com/

My two cents worth;

PVC is not recommended for air supply systems. Read large tank, large compressor, long lines. A rupture will tend to act like a loose fireshose and whip violently busting off sections. A good example is given at the last pumpkin chunking where one of the cannons lost a barrel because it folded over and rocketed into sections.

In spudding we don't use that much volume so the energy is much less when it does let go. It goes pop and pieces scatter, but there is no huge tank to really cause problems.. Except the big boys.. and you know who you are.

In general PVC is fine if you don't go overboard on size.

Hey Tech, not sure if you noticed but this thread is 3 years old. I dont think that your input, as great as it is, really matters anymore

I know Jeff replied first, but just ignore the new people until they get settled.

thedeathofall wrote:Hey Tech, not sure if you noticed but this thread is 3 years old. I dont think that your input, as great as it is, really matters anymore

I know Jeff replied first, but just ignore the new people until they get settled.

Thanks.. I wasn't paying attention. Oh well. I'll let it die again.