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 60 users online :: 6 registered, 0 hidden and 54 guests


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

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

The Team
Administrators
Global Moderators
global_moderators.png CS

Spud Gun Combustion

A place to ask general spud cannon related questions.
Sponsored 
  • Author
    Message

Spud Gun Combustion

Unread postAuthor: crazyfreak0075 » Fri Aug 18, 2006 4:45 pm

Havent yet built a lagre spud gun (only those of smaller size). And today i sprayed probly too much WD-40 into the chamber and it exploded. Luckily I wasent hurt. But the plastic was very thick (2mm to 2.5mm) and felt like it could take a beating. The potato gun was no bigger than my arm.

So heres the question. When I do build a spud gun out of pvc and of substantial size, is there a limit on how much fuel i can put into it. Or in other terms can there be such a thing as too much fuel. Thanks.
  • 0

User avatar
crazyfreak0075
Master Sergeant
Master Sergeant
 
Posts: 159
Joined: Thu Aug 17, 2006 4:09 pm
Reputation: 0

Unread postAuthor: Bluetooth » Fri Aug 18, 2006 4:57 pm

Yes i think there is a limit ive burst one of my combustions before you should use the combustion calculator.
  • 0

User avatar
Bluetooth
Brigadier General
Brigadier General
 
Posts: 863
Joined: Tue Jun 27, 2006 7:57 am
Reputation: 0

Unread postAuthor: carlbelcher » Fri Aug 18, 2006 4:57 pm

You probably used "DWV Cellular Core PVC" instead of SCH 40 PW Pressure rated PVC. Next time use pressure rated PVC and if you use too much fuel the cannon just won't fire instead of blowing up. (unless you're using acetylene or some other "death wish" fuel)

You are VERY lucky that you weren't injured or killed. NEVER use cellular core pipe.
  • 0

Is your Google.com Broken?!
User avatar
carlbelcher
Donating Member
Donating Member
 
Posts: 532
Joined: Mon Jun 12, 2006 6:54 pm
Reputation: 1

Unread postAuthor: crazyfreak0075 » Fri Aug 18, 2006 5:03 pm

Thanks for the info carlbelcher.

Bluetooth wrote:Yes i think there is a limit ive burst one of my combustions before you should use the combustion calculator.

But what is this calculator.
  • 0

User avatar
crazyfreak0075
Master Sergeant
Master Sergeant
 
Posts: 159
Joined: Thu Aug 17, 2006 4:09 pm
Reputation: 0

Unread postAuthor: carlbelcher » Fri Aug 18, 2006 5:16 pm

I don't think you or Bluetooth understand...

Even most non-pressure rated (not cellular core) can withstand the full pressure created by any reasonable fuel (hair spray, starter fluid, even propane, or mapp gas) the simple fact is that you can only use so much fuel, because there has to be a minimum air:fuel ratio for the fuel to ignite. So you can't just put "too much" fuel in your cannon and have it explode. If you put "too much" fuel there won't be enough air for the fuel to ignite and your cannon simply won't fire.
  • 0

Is your Google.com Broken?!
User avatar
carlbelcher
Donating Member
Donating Member
 
Posts: 532
Joined: Mon Jun 12, 2006 6:54 pm
Reputation: 1

Unread postAuthor: crazyfreak0075 » Fri Aug 18, 2006 5:19 pm

Okay now I understand.
  • 0

User avatar
crazyfreak0075
Master Sergeant
Master Sergeant
 
Posts: 159
Joined: Thu Aug 17, 2006 4:09 pm
Reputation: 0

Unread postAuthor: MrCrowley » Fri Aug 18, 2006 5:31 pm

you said the plastic was thick(2mm-2.5mm)umm thats not thick at all,
ive got some 4" dia pipe and the wall thickness is 1.5cm.
Did you use spouting pipe or something?Thats the only pipe i know of that thin.if you used DWV you would be fine on a combustion but spouting is way to thin its designed to carry water from your roofs gutter to the ground.
  • 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

Sponsored

Sponsor
 


Unread postAuthor: Mihlrad » Fri Aug 18, 2006 5:46 pm

Cellular core should not even burst from combustion especially if it isnt even using propane... There is no way in hell you used pvc pipe you used some kind of low grade stuff for just running water with 0 pressure. Also, regardless of the pipe you use, if you put in too much fuel, it will not fire. There is no way you put in too much wd-40 it would have just not ignited from lack of oxygen. Unless there is something you arent telling us, like you added air to the mix or something, than theres no way you used PVC, pressure rated or not.
  • 0

(\__/)
(O.o)
(> <)
This is Bunny. Copy Bunny into your signature to help him on his way to world domination.

www.Jerichofd.com
www.Hobbytimeny.com
User avatar
Mihlrad
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 467
Joined: Tue May 23, 2006 6:45 pm
Reputation: 0

Unread postAuthor: Dom » Fri Aug 18, 2006 5:51 pm

My ABS combustion as Schedule 40 written all over it.

Should never blow in my hands, right? (I know I'm redundant, I just prefer being annoying than being dead)
  • 0


Dom
2nd Lieutenant
2nd Lieutenant
 
Posts: 203
Joined: Sun Aug 06, 2006 4:54 pm
Reputation: 0

Unread postAuthor: Mihlrad » Fri Aug 18, 2006 5:55 pm

ABS is fine for combustion for the most part. Its always better to use pressure rated if you can get it, but combustion only generates 30-60 psi of pressure.
  • 0

(\__/)
(O.o)
(> <)
This is Bunny. Copy Bunny into your signature to help him on his way to world domination.

www.Jerichofd.com
www.Hobbytimeny.com
User avatar
Mihlrad
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 467
Joined: Tue May 23, 2006 6:45 pm
Reputation: 0

Unread postAuthor: crazyfreak0075 » Fri Aug 18, 2006 6:01 pm

Sorry I haven't been very clear. The gun wasent made from pvc instead a heavy duty pill bottle of substantial size (im guessing 30-40cc). Now I understand, I can't build spud guns out of that crap any more. It was way too thin.
  • 0

User avatar
crazyfreak0075
Master Sergeant
Master Sergeant
 
Posts: 159
Joined: Thu Aug 17, 2006 4:09 pm
Reputation: 0

Unread postAuthor: Mihlrad » Fri Aug 18, 2006 6:05 pm

Yea, that would be your problem... A pill bottle is not really able to withstand more than a drop of like purel or something combustion wise... Stay away from ghetto parts as often as you can, they are unsafe.
  • 0

(\__/)
(O.o)
(> <)
This is Bunny. Copy Bunny into your signature to help him on his way to world domination.

www.Jerichofd.com
www.Hobbytimeny.com
User avatar
Mihlrad
Lieutenant Colonel
Lieutenant Colonel
 
Posts: 467
Joined: Tue May 23, 2006 6:45 pm
Reputation: 0

Unread postAuthor: schmanman » Fri Aug 18, 2006 6:49 pm

go with all schedule 40 and you will not be sorry
  • 0

Persistence is a measure of faith in yourself
User avatar
schmanman
Major General
Major General
 
Posts: 1685
Joined: Sat Mar 25, 2006 12:28 pm
Location: Michigan,U.S.A
Country: United States (us)
Reputation: 0

Unread postAuthor: MrCrowley » Fri Aug 18, 2006 7:11 pm

i thought he was talking about a full scale combustion not some mini pill bottle crap lol :roll:
  • 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: drac » Fri Aug 18, 2006 10:49 pm

You can't have "too much" fuel in the chamber. There is a combustibility limit in air, and once you exceed that the fuel won't ignite.

It was most likely due to improper construction practices, or in your case, improper construction materials (not that it's ever stopped me ;)).
  • 0

User avatar
drac
Moderator
Moderator
 
Posts: 916
Joined: Sun Apr 24, 2005 8:56 am
Location: North Collins, NY
Country: United States (us)
Reputation: 2

Next

Return to General Spud Cannon Related

Who is online

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

Reputation System ©'