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Bumper Air Tanks Yea or Nay?
- Thread starter Dallin
- Start date
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NoReGrEtS
1/2 ton status
MarcS said:
Darn good research and thanks for being straight up and not tryin to lie
fireplug
1/2 ton status
MarcS said:
Interesting. Please update when you hear from them. I'm assuming that means National Highway something something?
fireplug said:
NHTSA = National Highway Traffic Safety Administration
bigjbear said:
Yep, that's them. Still haven't heard from them.
I have no reason to lie, I can admit if I am wrong, but I still stand by my opinion that these things should be designed and built properly though. If your some sort of mechanical engineer and certified in welding these kind of things, more power to you.
Judging by the pictures of welds on this site, most are not.
I've seen welds done by guys with military certification, you wouldn't believe your eyes how nice they are. But that's an extreme.
I'll post when I hear from the Highway guys.
SUPER'BURB
1/2 ton status
MarcS said:Judging by the pictures of welds on this site, most are not.
Thats why I had a bud that welds full time weld mine up.
I can weld but it looks like I sneezed on the stuff
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SUPER'BURB said:Thats why I had a bud that welds full time weld mine up.
I can weld but it looks like I sneezed on the stuff
Mine looks like I stitched up a cow's ass with a grapevine but none of the grapevines have broken yet.
loafer
1/2 ton status
I made an excel spreadsheet to calculate the minimum tube wall thicknes and end plate thickness for cylindrical pressure vessels.
Just enter in the desired tube OD, pressure, and material properties. (I've included sample values)
The sheet also demonstrates the advantages of using spherical end caps on the tubes instead of flat end caps.
The stress in the welds to hold the end caps on does NOT change by using flat plate instead of a spherical cap. The thickness of the material is the only thing that changes.
It should also be mentioned that a pressure relief safety valve should be installed.
OK. It seams that .xls files are not valid for attachment. Is there a way to change this? I've attached a .pdf file as an example. Email me if you want a copy of the xls file, or can host it on a server.
Just enter in the desired tube OD, pressure, and material properties. (I've included sample values)
The sheet also demonstrates the advantages of using spherical end caps on the tubes instead of flat end caps.
The stress in the welds to hold the end caps on does NOT change by using flat plate instead of a spherical cap. The thickness of the material is the only thing that changes.
It should also be mentioned that a pressure relief safety valve should be installed.
OK. It seams that .xls files are not valid for attachment. Is there a way to change this? I've attached a .pdf file as an example. Email me if you want a copy of the xls file, or can host it on a server.I would say that you've missed a calc then. A flat plate attached at the edges under pressure in any cross section will look like a simply supported beam with two fixed ends. Those ends will resist the bending moment. That is stress in the welds that isn't accounted for.
Found some new info on this. This is a link to the DOT codes that cover pressurized tanks:
http://www.access.gpo.gov/nara/cfr/waisidx_02/49cfr178_02.html
The pdf's in particular are 178.50, 178.51 and 178.61
http://www.access.gpo.gov/nara/cfr/waisidx_02/49cfr178_02.html
The pdf's in particular are 178.50, 178.51 and 178.61
destinbeachman
1/2 ton status
Doesn't seem to bother anyone around here to do their own brakework or steering and/or suspension mods.It shouldn't bother them to build a half-decently thought out bumper with air tank capabilities either.-Allen-ASME-Purdue '94
as long as you use at least 3/16 and keep around 120. i can't see you haveing any problem. i have worked as truck mechanic for 23 years and never seen an air tank explode even when punctured. the air just rushes out. its all a myth.
OrangeCrushK10
1/2 ton status
No. Bad Idea.
I keep seeing "Punctured" this, "Punctured" that. If he is in any kind of collision, this bumper is not going to get punctured, it will be crushed.
Think about it.
First, a volkswagon beatle going 5 mph has about the same amount of power as a .50 BMG (Do the math for those of you that are scoffing right now). Imagine what a 5,000lbs vehicle going at 25mph will do. You're looking at 10x the power behind a .50 BMG bullet just out of the barrel. A lot more than a claw hammer.
Also as I first pointed out this is not puncturing damage. This would be crushing damage. That 150psi is going to grow exponentially when that air tank bumper is reduced to half it's normal size in under half a second.
I would be suprised if some explosion DIDN'T occur.
Now, are you going to get into a 25mph collision with another K5? Possibly not. But this is your bumper. It's designed with that in mind. And it does happen. I know from when I was plowed into at 50mph by an S-10 blazer while sitting at a stop light.
And, if nothing about it being unsafe gets you, then atleast respect the laws. I don't care what I hear about some of us worrying about laws too much. I wanna hear that same person complain when their wheeling trail gets shut down because people weren't obeying the laws.
I keep seeing "Punctured" this, "Punctured" that. If he is in any kind of collision, this bumper is not going to get punctured, it will be crushed.
Think about it.
First, a volkswagon beatle going 5 mph has about the same amount of power as a .50 BMG (Do the math for those of you that are scoffing right now). Imagine what a 5,000lbs vehicle going at 25mph will do. You're looking at 10x the power behind a .50 BMG bullet just out of the barrel. A lot more than a claw hammer.
Also as I first pointed out this is not puncturing damage. This would be crushing damage. That 150psi is going to grow exponentially when that air tank bumper is reduced to half it's normal size in under half a second.
I would be suprised if some explosion DIDN'T occur.
Now, are you going to get into a 25mph collision with another K5? Possibly not. But this is your bumper. It's designed with that in mind. And it does happen. I know from when I was plowed into at 50mph by an S-10 blazer while sitting at a stop light.
And, if nothing about it being unsafe gets you, then atleast respect the laws. I don't care what I hear about some of us worrying about laws too much. I wanna hear that same person complain when their wheeling trail gets shut down because people weren't obeying the laws.
PV=nRT if the bumper volume is reduced by half the pressure inside would double. The pressure would not grow exponentially. The pressure volume relationship is linear. I guess you could argue that crushing the bumper quickly would produce shock waves. If the bumper was filled with water that may be an issue, but air is compressible. Shockwaves in air at worst would create a pressure spike of a few PSI
I think you meant energy not power on the bullet thing. Either way I'm not really sure what you were trying to say.
I don't think we have established that this is unsafe or illegal? Did I miss a post?
I think you meant energy not power on the bullet thing. Either way I'm not really sure what you were trying to say.
I don't think we have established that this is unsafe or illegal? Did I miss a post?
OrangeCrushK10
1/2 ton status
Dallin said:
Yes, I meant Energy, not Power. My mistake for using the wrong word. Power would be the measurement for an amount of force over an amount of time, IIRC.
What I was trying to say is that smacking an airtank with a claw hammer isn't anything similar to hitting an air tank with a car. Even a very thick air tank. I used the bullet analogy because people here know pretty well the amount of damage a bullet will do. This was a way to rationalize about how much energy we're talking about.
And so far I'd lean towards it being illegal. I've seen nothing saying it IS legal and a few thing pointing the the direction of NOT legal. But perhaps I misread them.
justinf
1/2 ton status
OrangeCrushK10 said:
So do you assume everything is illegal, until it is proven legal?
Anyways, unless I missed these things pointing to bumper air tanks being illegal, I am under the impression that the DOT is saying they are legal
MarcS said:
the last part to me is their way of covering their butt, since local officials can pass more stringent laws, so it is possible that it is illegal somewhere, but no one has presented a law saying that it is definitely illegal.
Personally, I would be a lot more concerned with someone welding/fabricating their own suspension parts, steering, or brake systems than someone making a bumper air tank. Seems to me that is a hell of a lot more likely to fail and kill someone than a bumper air tank possibly being crushed and "maybe" exploding sending shrapnel into everyone around.
Yet, trying to talk people out of building their own suspension parts, steering or brake systems doesn't seem to rate as high as talking people out building bumper air tanks.
destinbeachman
1/2 ton status
Trying to hide
Y'know,not often,but every once in a while I'm actually embarrassed to be a member of this site.
Y'know,not often,but every once in a while I'm actually embarrassed to be a member of this site.
justinf
1/2 ton status
destinbeachman said:Y'know,not often,but every once in a while I'm actually embarrassed to be a member of this site.
So was that directed at me
OrangeCrushK10
1/2 ton status
justinf said:So do you assume everything is illegal, until it is proven legal?
...
Yet, trying to talk people out of building their own suspension parts, steering or brake systems doesn't seem to rate as high as talking people out building bumper air tanks.
No, that's ridiculous. But I am sure there are certain standard and such put in place for this particular topic.
Also -
When it comes to people screwing around with their 2,000+ lbs of machinery that can be very dangerous or deadly, then I *don't* think they should alter them unless they know what they are doing.
And I don't mean *think* they know what they are doing. I mean actually taking the time to research the topic and taking some classes and becoming certified to do it.
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