Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 64 users online :: 5 registered, 0 hidden and 59 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Exabot [Bot], Google Adsense [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

dwv

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
Sponsored 
  • Author
    Message

dwv

Unread postAuthor: KVINCEO » Sun Oct 15, 2006 5:28 pm

i understand it is not pressure rated, but how much pressure can it handle? in particular, a threaded 2" threaded end, because the majority of it is covering sch 40 pvs is it safe? and at what psi is it not safe. don't tell me not to use it. just wanna know what it can take
  • 0

User avatar
KVINCEO
Private First Class
Private First Class
 
Posts: 37
Joined: Wed Oct 04, 2006 5:03 pm
Reputation: 0

Unread postAuthor: MrCrowley » Sun Oct 15, 2006 7:46 pm

well i doubt theres a set pressure more a range, i would say between 125-150psi its unstable and dangerous to use e.g it could blow at any second or if you accidently drop it etc.
  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: mark.f » Sun Oct 15, 2006 7:51 pm

All PVC can blow any second if you accidentally drop it etc.

KVINCEO, you wanna know what DWV can take?

DWV cannot take ANY pressure above 1 atm. Any higher and it will explode and kill you.

THERE'S YOUR ANSWER.

Get a pressure rated threaded adapter, cheapskate.
  • 0

User avatar
mark.f
Donating Member
Donating Member
 
Posts: 3465
Joined: Sat May 06, 2006 11:18 am
Country: United States (us)
Reputation: 21

Unread postAuthor: frankrede » Sun Oct 15, 2006 8:09 pm

DWV can take pressure.
Its been past 100 without fail.
If you had to use it then stay under 60 psi.
  • 0

Current project: Afghanistan deployment
User avatar
frankrede
Lieutenant General
Lieutenant General
 
Posts: 3220
Joined: Thu Jul 20, 2006 9:47 pm
Reputation: 0

Unread postAuthor: KVINCEO » Sun Oct 15, 2006 8:35 pm

alright, i was gonna use it at lower pressures anyway, thanks. and im not a cheapskate, they just did'nt have it at the local hardware stores, and im a guy who can't wait for crap, very impatiant. but thinkin about it, i think ill hack of the dwv end and look a little harder for a pressure rated fitting, thanks everyone. oh and mr.crowleyyour quote is very true and mark, nice quote as well.
  • 0

User avatar
KVINCEO
Private First Class
Private First Class
 
Posts: 37
Joined: Wed Oct 04, 2006 5:03 pm
Reputation: 0

Unread postAuthor: CS » Sun Oct 15, 2006 10:06 pm

Here it is, a previous attempt to clear up the muck. As you can see I spent some time writing, and believe it to be of some use, of course the reason I wrote such. Read it for what its worth...

PimpMann22 wrote:This is where a the bell curve and 3 sigma standard come into play. Below I made a rough assumption of what one would look like for the bursting pressure of PVC pipe by simply adding some numbers to a already existing graph I found on the net, shown below.

Image

Basically the height of the curve denotes the percentage of a given event occurring. In our case, the possibility of the pipe bursting. The most common percentage is listed in each 8 portions the curve has been divided into. And the further 'right' you move on the graph the higher results the given situation produces. In our case, a higher burst pressure. As you can see I went ahead and listed some numbers to give a idea on what the bursting pressures would roughly look like. Pretend as if I went out and tested 10,000 pipes for there bursting pressure and what I got is what is listed on the graph.

Since the height of the wave occurs at 250PSI, that also means that the median bursting pressure is 250PSI. Although a major fluke in production that produces weak chemical bonds in the PVC occurs .13% of the time resulting a low bursting pressure [0-40PSI], and another .13% of the time a uber-strong bond is formed by the PVC resulting in pressure withstanding capabilities of 500+PSI. Both these instances are rarely accounted since of there rarity. The other 6 portions are more plausible, and increase with there likeliness as there height in the curve increases.

So if you were to go test a section of pipe according to this data the pipe would most likely burst at around 250PSI. But you dont want to approach anywhere close to that median in fear of failure. So to accommodate for this fear they will rate the item at a negative deviation of the median. Something such as pipe is held to high negative deviations since failures of such can result in serious injuries or death. While something such as rubber band is not, since what happens when a rubber band snaps? Nothing, so it doesnt need that high of standards. Problem being some companies will get greedy and rate a product at a lower deviation to make there product appear better. But most industries can venture into -4 deviation on a 3 sigma standard since in the pipe industry that would require you to make a 1" thick pipe rated for 10PSI to be absolutely sure it will not fail.

Chances are that pipe companies have tested huge amounts of pipe for there failure point and had a few fail under there claimed safety figure, but the chances of someone having such fail on them is so low, its accepted. I mean there wouldnt be a pharmaceutical drug on the market if they were held to a -4 deviation on a 3 sigma standard.

This is why we avoid even approaching the stated pressure rating of pipes since as we can conclude that there is proven flukes that may end in our possession. The results of a failure in our instance is not acceptable, hence why its held to such high standards. Damn I hate when I have to sit here and cover something so extensively before someone understands...

[Ill admit the bell curve actually graphed for our situation would be steeper, but you get the idea ;-) ]

EDIT- Ive edited the post a billion times in a attempt to get the picture to work, and finally got it working. Its now working, and not a worry. MrCrowley, thanks for the heads and now I will delete your post since it has no matter in this discussion.
  • 0

User avatar
CS
Donating Moderator
Donating Moderator
 
Posts: 1897
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah
Country: United States (us)
Reputation: 4

Return to Pneumatic Cannon Discussion

Who is online

Registered users: Bing [Bot], Exabot [Bot], Google Adsense [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'