Originally Posted by
wadarbr549
this is slightly off subject but i used to deliver for big sandy furniture when i was laid off to pick up extra cash.i remember when it was below 32 degrees we were required to tell folks to wait till the tv sat in a room at room temp for 24 hours befor they even plugged it in.i am sure these tv,s were not liquid cooled.i always thought it had something to do with possible condensation im not sure.i just no it was our policy to tell them not to use them for 24 hours
The thick glass front of the screen would have gotten real cold. Real real cold. If the TV was used, the rear thinner funnel part of then screen would have heated up to the usual temp while the front would still be cold.
There's a glass seam where the front joins the funnel.
The tubes got a vacuum in it. In theory the tube is under a of of pressure from the atmosphere. A LOT of pressure....
Now that seams got a lot of pressure on it, that pressure means energy. Now if the funnel expands and the fronts still cold, the join is the weak point and the tube will crack on the join.
That's when everything goes to hell in a split second.
You know the Arcoroc cups and dinner plates? Made from safety glass.. You may have seen one of these explode.
Its because the glass itself is under pressure because they heat it up to red heat and suddenly cool it down. The outside cools quicker and then that puts pressure on the internal hot glass and when its cold the pressures still there. (I know someone who operates one of these kilns for window glass).
All you have to do is scratch the outside of the glass to weaken its integrity, this causes a weak spot and suddenly all the energy is released and the cup explodes.
The same with car windows, they shatter into thousands of peices. For some reason crockery and ceramic will do this without any effort at all if they scratch the glass.
Back to the CRT TV, the join between the two glass peices cracks, the vacuum energy takes over and the screen explodes.
No, I did not say 'Cracks'. I said EXPLODES!!!
From flakes to 3 inch long shards flying everywhere with force. Just like a hand grenade, this glass will slice flesh like butter, actually worse.
It will take out anything within 15 feet.
That's why you should always be carefully with screens and release the vacuum pressure before scrapping them down.
I, using glasses and should be wearing a face shelf protecting my neck and full arm coverings, maybe a blanket over the exposed rear of the screen.
Then I grab the board that's plugged to the rear of the screen, like a cars steering wheel with both hands and twist it like I am turning a corner so it breaks the screen where the wires go into it.
At that point you can hear the air rush into the screen, I like a fast rush rather than a long slow whistle. The faster the quicker the screens up to normal pressure inside and the less chance of it going BANG.
Now, how did I find this out?
Experience.....
I had placed a 29 inch CRT screen face down on a waist height rubbish bin and decided to lever off the steel band around the screen with a screwdriver....
Stupid move.
I had not released the pressure inside the screen. And the screwdriver blade broke the screen directly on the join.
It EXPLODED!!!
I can still see the pressure wave that came off the screen... And a circle of broken screen glass shards 15 feet in diameter, like square sharp tapered icicles inch to 3 inch long.
There was a section of the circle missing from behind where I was standing, I hardly had any glass on me and I still cannot believe that I never got badly cut, let alone still have eyesight......
The energy tied up in that vacuum is phenomenal.
Never underestimate the damage that the vacuum inside the screen can do.
Do not tell anyone who is not actively doing CRTs, as information in the hands of idiots is more dangerous than the idiots themselves.
Oh, and don't pick up the CRT screens by the steel band. Its often loose and the screen will drop out of it.
I know TV repairmen use a thick heavy, like lead lined heavy, blanket to cover the screen while putting them into the TV, or replacing them.
They also get taught about the vaccum. Unless you see it happen, you really have no full idea on what it can do.
But never try and find out either.
Its all to do with the weak point where the join is under the steel band.
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