breaking tempered glass doors/windows

Safety and hazards on the job...
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PFD023
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breaking tempered glass doors/windows

Postby PFD023 » Thu Apr 10, 2008 6:14 am

I've read that the proper method of breaking tempered glass doors/windows (only as a last resort!!) during forcible entry should be done by striking the lower corner of the door/window.....I'm referring to residential/commercial buildings here....not vehicles. I just need to know why. I would imagine it has to do with safety since this glass can explode but I just need confirmation. Couldn't find any reasoning on the web or in any text. Anyone help a brother out?
Last edited by PFD023 on Thu Apr 10, 2008 6:17 am, edited 1 time in total.

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PellattFire
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Postby PellattFire » Thu Apr 10, 2008 7:54 am

[quote=""PFD023""]I'read that the proper method of breaking tempered glass doors/windows (only as a last resort!!) during forcible entry should be done by striking the lower corner of the door/window.....I'm referring to residential/commercial buildings here....not vehicles. I just need to know why.[/quote] It has to do with reducing flex.
Tempered glass needs to be broken with a focused pressure point in an area that can't flex to absorb the pressure.
The best places to do this are the corners where the reinforcement(sills) are closest to the break point.
It's not a safety issue.
It's an efficiency issue.
Out of this nettle, danger, we pluck this flower, safety.
~William Shakespeare

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PFD023
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Postby PFD023 » Thu Apr 10, 2008 8:37 am

[quote=""PellattFire""]It has to do with reducing flex.
Tempered glass needs to be broken with a focused pressure point in an area that can't flex to absorb the pressure.
The best places to do this are the corners where the reinforcement(sills) are closest to the break point.
It's not a safety issue.
It's an efficiency issue.[/quote]

IFSTA text specifically says bottom corners.....thats what is throwing me off. All other glass is typically broken windward side...top portion to prevent glass from coming down on top of you. The IFSTA text says with tempered it's the bottom corner...why not the top corner? I understand the physics involved with tempered (surface compression)..just not the logic of the bottom corner as opposed to the top. Is there any logic behind this?
Thanks for the reply PellatFire.

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PellattFire
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Postby PellattFire » Thu Apr 10, 2008 9:00 am

[quote=""PFD023""]IFSTA text specifically says bottom corners.....thats what is throwing me off. All other glass is typically broken windward side...top portion to prevent glass from coming down on top of you. The IFSTA text says with tempered it's the bottom corner...why not the top corner? I understand the physics involved with tempered (surface compression)..just not the logic of the bottom corner as opposed to the top. Is there any logic behind this?
Thanks for the reply PellatFire.[/quote]
This is just a guess but the most pressure pressure on the window will be at the bottom as the weight of the window itself adds to this.
Also the weight of the glass might cause the spidering to continue up the window. Sort of like the window is falling into the break.
I have never had an issue with a top break with a tempered window though.
Never done a big storefront sized baby though so maybe there is a difference with those.
Out of this nettle, danger, we pluck this flower, safety.
~William Shakespeare

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FitSsikS
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Postby FitSsikS » Thu Apr 10, 2008 9:01 am

[quote=""PFD023""]...just not the logic of the bottom corner as opposed to the top. Is there any logic behind this?
[/quote]

Firstly, you can always reach the bottom corner, secondly it's a safety issue.
When reaching up there is more of a chance of falling towards or through the glass in question.
On paid duty 24/7........................a month.

cranky
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Postby cranky » Thu Apr 10, 2008 4:47 pm

[quote=""FitSsikS""]Firstly, you can always reach the bottom corner, secondly it's a safety issue.
When reaching up there is more of a chance of falling towards or through the glass in question.[/quote]

The glass if broken at the bottom will fall onto itself allowing for a (mostly) complete cleaning of the frame, ergo the safety issue. Also tempered glasss breaks into tiny fragments, could cause an eye injuries, cuts etc. it would be safer to break at the bottom as oppoosed to the top. As long as you gain access it doesn't much matter how you do it, but bottom is better, safer and more efficient.
If I have to explain you wouldn't understand anyway.

tjackson
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Postby tjackson » Mon Sep 10, 2012 6:17 am

Tempered glass is extremely hard and breaks in a unique way. If any part of the glass fail,the entire panel shatters at once.


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