Fire Extinguisher (Glad it wasn't my rig) (1 Viewer)

[Ebag333]

I have also thought about using this spot for mine but this spot makes the extinguisher a significant missile if in an accident.:whoops: All it would take is for someone to pull out in front of you causing a rapid deceleration upon contact and the extinguisher is becomes lodged in the skull of an occupant.

IMHO - I think a good metal bracket for the extinguisher and being drilled through where the seatbelt mounts would be the most secure.

How do you figure? The seatbelt bolt keeps the panel from coming off, and the extinguisher bracket keeps the extinguisher from coming off.

In order for it to become a missile you'd have to havet he plastic panel break enough that it can come loose from the seatbelt bolt (at the minimum, far more if you have the seatbelt itself there). The force required to break the panel that much would be huge given that there's very little movement, and even with the extinguisher mounted on it there's not much weight. You'd pretty much have to break the entire panel in half, and plastic tends to bend/deform rather than snap clean off.

The fact that it's also held in place by the molding means it's supported in more than one area, and makes it even more difficult for that to happen.


Far more likely than the panel snapping in two is the bracket holding the extinguisher itself. However, they are designed to hold the extinguisher in place even with significant vibration/movement/force/etc against it. In my folks boat, the brackets for both extinguishers has held perfectly fine, and when you're going 55 mph across a lake with chop it can be about like a car accident every few seconds, knock a few teeth loose.

I've yanked on the extinguisher itself, put my whole body weight into it. If 200 lbs can't pull it loose (either the panel or the bracket), it would have to be one heck of an accident to pull it loose. Like maybe falling off a 300 foot cliff.......



I actually had it mounted when my truck was rear ended (hit and run). A gal hit my truck hard enough to move it sideways about 6", and probably would have gone farther had it not been for the curb that the tires were pressed (hard) against. She pretty much hit dead on that corner, which would have been force directed straight at the extinguisher, as close as you could get.

The extinguisher didn't come off, wasn't even loose. So I'm not worried in the least.

 

[EricG]

How do you figure? The seatbelt bolt keeps the panel from coming off, and the extinguisher bracket keeps the extinguisher from coming off.

In order for it to become a missile you'd have to havet he plastic panel break enough that it can come loose from the seatbelt bolt (at the minimum, far more if you have the seatbelt itself there). The force required to break the panel that much would be huge given that there's very little movement, and even with the extinguisher mounted on it there's not much weight. You'd pretty much have to break the entire panel in half, and plastic tends to bend/deform rather than snap clean off.

The fact that it's also held in place by the molding means it's supported in more than one area, and makes it even more difficult for that to happen.


Far more likely than the panel snapping in two is the bracket holding the extinguisher itself. However, they are designed to hold the extinguisher in place even with significant vibration/movement/force/etc against it. In my folks boat, the brackets for both extinguishers has held perfectly fine, and when you're going 55 mph across a lake with chop it can be about like a car accident every few seconds, knock a few teeth loose.

I've yanked on the extinguisher itself, put my whole body weight into it. If 200 lbs can't pull it loose (either the panel or the bracket), it would have to be one heck of an accident to pull it loose. Like maybe falling off a 300 foot cliff.......



I actually had it mounted when my truck was rear ended (hit and run). A gal hit my truck hard enough to move it sideways about 6", and probably would have gone farther had it not been for the curb that the tires were pressed (hard) against. She pretty much hit dead on that corner, which would have been force directed straight at the extinguisher, as close as you could get.

The extinguisher didn't come off, wasn't even loose. So I'm not worried in the least.

That looks like a 10 lb extinguisher. You can get up to 50g's out of a bad accident, so that's 500 lbs yanking on that. And plastics get brittle with age & fatigue.

I personally wouldn't mount it only on plastic and that high. But your call.

 

[Torquey]

How do you figure? The seatbelt bolt keeps the panel from coming off, and the extinguisher bracket keeps the extinguisher from coming off.

In order for it to become a missile you'd have to havet he plastic panel break enough that it can come loose from the seatbelt bolt (at the minimum, far more if you have the seatbelt itself there). The force required to break the panel that much would be huge given that there's very little movement, and even with the extinguisher mounted on it there's not much weight. You'd pretty much have to break the entire panel in half, and plastic tends to bend/deform rather than snap clean off.

The fact that it's also held in place by the molding means it's supported in more than one area, and makes it even more difficult for that to happen.


Far more likely than the panel snapping in two is the bracket holding the extinguisher itself. However, they are designed to hold the extinguisher in place even with significant vibration/movement/force/etc against it. In my folks boat, the brackets for both extinguishers has held perfectly fine, and when you're going 55 mph across a lake with chop it can be about like a car accident every few seconds, knock a few teeth loose.

I've yanked on the extinguisher itself, put my whole body weight into it. If 200 lbs can't pull it loose (either the panel or the bracket), it would have to be one heck of an accident to pull it loose. Like maybe falling off a 300 foot cliff.......



I actually had it mounted when my truck was rear ended (hit and run). A gal hit my truck hard enough to move it sideways about 6", and probably would have gone farther had it not been for the curb that the tires were pressed (hard) against. She pretty much hit dead on that corner, which would have been force directed straight at the extinguisher, as close as you could get.

The extinguisher didn't come off, wasn't even loose. So I'm not worried in the least.

Again, I like the spot and plan to put my extinguisher where my seat belt used to be but I will absolutely use an metal bracket and secure it to the steel behind the panel. The mounting is only as good as its weakest link. The plastic mount holding the extinguisher is not designed to withstand the forces in an auto accident, they are designed for stationary mounting. Your example of the rear end incident does not include the deceleration of a frontal impact. If you were off-roading at only 20 mph and hit a boulder or a tree, that little plastic tab will have to hold hundreds of pounds worth of kinetic energy. Putting your weight against it is not a test of the bracket’s strength. It you want to see how weak the bracket is you could get inside the cruiser and try to pull it toward the occupants. Automotive specific mounting brackets for extinguishers are almost always made from metal (sometimes heavy straps). As an example, that cheapo plastic bracket would not be allowed by any sanctioning organization in the US for any type competition.

Here are some options that could solve the problem:

Brey Krause R-9521 - Rollbar Fire Extinguisher Mount, 1.5" And 40 MM

http://www.stoodyind.com/Catalogs/FISC/current/05catpg602.pdf

http://www.h3rperformance.com/products.htm

http://www.saferacer.com/rennline-porsche-fire-extinguisher-mount.html?productid=2125

 

[Ebag333]

That looks like a 10 lb extinguisher. You can get up to 50g's out of a bad accident, so that's 500 lbs yanking on that. And plastics get brittle with age & fatigue.

I personally wouldn't mount it only on plastic and that high. But your call.

10 lbs even at 50 g's doesn't compare to 200 lbs, even at relatively low G's. I was not gentle when yanking on it.

The plastic is not brittle. I know this first hand as I drilled through it, and have also flexed it to test to make sure it was not brittle. It doesn't get that much sun as it's inside the vehicle, and somewhat protected by the tinting on the windows, so not much UV exposure. It is also surprisingly thick.

In order for the plastic to break or come off, it'd have to do so in two sections. One where it wraps around the lift gate opening, and where the seatbelt bolt goes through. Considering any force will be distributed through both areas, you're talking about that 50 g's distributed over a very large area.

The way I mounted the extinguisher mount spreads the force out over a large area. I almost just ran the bolts through with some washers, but it'd be possible for the plastic to deform and the bolts to pull through. Mounting the bolts through steel plate effectively makes that impossible.

My biggest concern is the single band that clamps the extinguisher to the mount. That, if anything, is going to be the point of failure. But again, literally throwing my weight against it has failed to pull it loose. I've actually considered upgrading the bracket to something more substantial, preferably with two straps to hold it in place instead of a single strap. The down side is the more secure you make it, the longer it takes to get out, and fire grows in size quite rapidly (doubles every minute, and that's burning without accelerants).

Hmm, I should probably just get this.

 

[EricG]

10 lbs even at 50 g's doesn't compare to 200 lbs, even at relatively low G's. I was not gentle when yanking on it.

You're right - 10 lbs @ 50 g's is much higher then what you were able to apply yanking on it.

Think of it this way - put two guys your size and a small woman on a pallet. Suspend that from a rope and run it through a pulley so it's horizontal. Think you could yank on that rope horizontally, from inside a truck hard enough to lift them off the ground?

That's how much force that mount will have to withstand in a bad head-on.

 

[Ebag333]

You're right - 10 lbs @ 50 g's is much higher then what you were able to apply yanking on it.

Think of it this way - put two guys your size and a small woman on a pallet. Suspend that from a rope and run it through a pulley so it's horizontal. Think you could yank on that rope horizontally, from inside a truck hard enough to lift them off the ground?

That's how much force that mount will have to withstand in a bad head-on.

It's way more complex than that. A head on is over in literally seconds, while my yanking on it is applying force over time. Plastic is more likely to crack under a sudden impact, but deform over time. Also, the fact that there's no direct impact on the extinguisher comes into play as well.

The good thing is that ABS plastic has a very high impact and tensile strength....which is why they use it in autos to begin with.

Look, either way it'd be childs play to run the metal bracket behind the plastic up to the seat belt bolt. I considered that, but decided it was unnecessary, the plastic strap on the mount will fail long before the plastic panel or the steel holding the bracket in place.

I've seen many of these extinguishers mounted with the single plastic strap, and I've seen more than one in an accident. I've never seen one that's failed.

For the record, my pop's is a firefighter with 30 years of experience. I asked him if he was concerned, his biggest concern was the plastic deforming and letting the bolts pull through. When I showed him the steel backing plates, he thought it was safer than most extinguishers he's seen mounted. And he's seen a lot (of extinguishers and accidents both).

Like I said though, just extend the backing plate up to the seat belt bolt and use a metal bracket instead of a plastic one. Then you'd be able to use it as a lifting point for your HiLift.

 

[98 SNAKE EATER]

That looks like a 10 lb extinguisher. You can get up to 50g's out of a bad accident, so that's 500 lbs yanking on that.

If your body was subjected to 50g's, you'd probably be dead anyways

 

[7schulz]

What about mounting a couple of these so you don't have to worry so much about clean up and the ones not working like the OP?
Cold Fire Rapid Cooldown Spray

 

[Ebag333]

If your body was subjected to 50g's, you'd probably be dead anyways

And that's part of it as well. While the force of the impact could be 50 g's, your body doesn't see it, because the vehicle is designed to absorb and transfer much of the impact. That's why newer vehicles are designed to crumple, older vehicles that didn't would transfer the force of the impact from the collision to the occupants, causing much more trauma.

The same principle would be at play on anything inside the vehicle, including the fire extinguisher.

Which is why in accidents such as this one, the occupant lives rather than the shock killing them instantly.

Any impact that creates enough force to rip out the extinguisher will also likely kill the occupants instantly.

Mythbusters regularly uses the Shockwatch stickers to gauge the force of impact. 50 g's is considered beyond dead, without a doubt. 25 g's is considered major injuries (and possible death).

 

[Torquey]

Again, why risk it? Why use a plastic strap designed for a static wall mount on a car when a $10 metal bracket will hold the extinguisher?

Fire Extinguisher Brackets - Kidde Mounting Brackets

 

[Ebag333]

Again, why risk it? Why use a plastic strap designed for a static wall mount on a car when a $10 metal bracket will hold the extinguisher?

Fire Extinguisher Brackets - Kidde Mounting Brackets

Because it comes down to either carrying the extinguisher, or not carrying it at all. I had the existing bracket (which is listed as being used for auto, marine, home, RV, etc, so it's not a "static wall mount"). I did not have on hand the metal bracket.

I'll probably upgrade to the metal bracket at some point, but for now I'm comfortable with what I got. If my extremely conservative father is happy with it, then I am too. Usually he's the one worried about stuff and I'm the one going "aww, it's fine."