Safety glass -- how necessary?

[Phil Nelson]

I understand the reasoning behind putting a safety glass in old TVs.

I'm wondering whether anyone has seen or heard of a case in which a CRT imploded during normal operation.

Trying to think of a scenario in which this occurs. Maybe a Bad Thing happens while you're watching Bonanza, causing a chassis fire, and then the CRT pops . . . ? Or would the CRT just pooch out backward, leaving the front intact?

Was the glass there to protect against a significant danger? Or merely an extra precaution against the occasional ape who bashed the TV while trundling it around the house?

Phil "just curious" Nelson

[David Roper]

Somebody who is very very diligent, patient and lucky would probably be able find an AK post from about 18 mos. ago which was a scan of a 1955 article about the spontaneous implosion of the CRT in a very recent-model RCA table set.

I'm sure somebody remembers the picture of the set sitting in a corner of some poor woman's apartment with glass shards all about and noticable mangling to the chassis--plainly visible through the empty CRT surround.

The safety glass was blown out by the force IIRC, so how effective it really could be is debatable.

But that is, of course an isolated--if not unique--incident.

[andy]

...

[wa2ise]

Back in the day, my brother and I tossed an old TV into a lonely dumpster. It didn't implode. So I tell my brother that TVs had to be built to take the rigors of shipping....

[MRX37]

I wouldn't want to be near an older CRT without safety glass...

[peverett]

I did read about one person being killed by a CRT imploding. What happened was that family members were fighting. In doing this, they were throwing a small TV set around and at each other. One of the participants went to pick it up and it imploded, sending glass into her neck.

When I was young, a local person who sold TVs was killed in his shop. I had always thought that this was also due to a CRT imploding. However, I later found out that this person was using a lathe and something flew off of it and killed him. Not related to TVs at all.

I too am VERY cautious when working with tubes w/o integral implosion protection. Think about it...even in the 1940's, well before the heyday of injury lawyers, manufacturer's were plastering "caution" notices on both the tubes themselves and on the insides of TV cabinets, warning about the possibility of serious injury when removing or replacing even a small 10 or 12 inch CRT, let along a 21 inch or larger. The service manuals of these sets even went so far as to highly recommend eye protection and arm protection.

When you consider how many things of that era were also truly "dangerous", yet carried no warnings (ie big ole' GE fans with brass blades and little to no guarding), there was obviously some well-founded basis for the concerns, even outboard of strict legal liability.

[jpdylon]

I couldn't find the thread, but here's the article I posted:

[nasadowsk]

Not just TVs that pop, every now and then you hear about a car window spontaniously breaking, especially in the heat. If the car's relatively new, most manufacturers will chip in to pay, even if it's out of warranty..

[RetroHacker]

Any kind of manufactured glass product like this has the potential for a manufacturing defect to suddenly spring up. Any time glass is worked, there are stresses involved. And glass is really more of a very, extremely, slow moving liquid anyway. It can change a bit in shape over time - and if it was stressed or defective in some way, I could see how it would crack. Car windows, being tempered, are laminated with plastic and somesuch - and a tiny crack or break can spread very quickly. Especially something like a windsheild that is glued in all around, and if the metal of the car deforms somehow, or is putting pressure on it, the crack would expand as well. Picture tubes are full of vacuum (or is that not full of it... ). Lots of pressure is trying to crush the tube from the outside. One little crack in the right spot and *FOOMP!*.

Modern tubes have the "integral implosion protection" which is just a tensioned rimband around the outside, to crush the tube in on itself if it breaks. Old tubes, without this, lived behind glass, just in case.

One thing I've wondered - is on the 21FJP22, with the bonded safety glass, what happens if it implodes and the glass has been de-glued due to cataracts and taped back on? It should provide protection, but will it stop glass from flying everywhere?

But, all that aside, these things really have a one in a million chance of spontaneously imploding if they're not abused/kicked/dropped.

But still. The set came with a very durable glass in front of it, and I think that leaving it there is a good idea - but I wouldn't lie awake at night if it were missing. Any spontaneously occurring crack is most likely to happen at the weakest area of the tube AFAIK. That would be the neck or stem. And such failure would be just a hiss as the vacuum escaped. Nothing spectacular.

I've never had a tube implode unexpectedly. I've had some tubes unexpectedly NOT implode though - modern tubes at least are very tough. When throwing away some dud modern tubes, even chucking it into a dumpster won't always break it (the face and sides are very thick).

-Ian

[andy]

...

[peverett]

I have radios built in the 1940s where if a knob is removed or you touch one of the screws holding the chassis in , you could be touching 120VAC (if it was plugged in). Even some of the early Hoffman TVs that I have have a live chassis where safety depends on paper type insulation. Would not fly today at all.

I also have a 1963 Ford Falcon-no fan shield on this model (as well as a solid steel steering column). One of my mother's brothers was killed by a car with no fan shield-the fan flew apart as he was working on it and hit him in the head.

In general, safety is a much higher priority in things built today.

Originally Posted by andy

They won't be any worse than a 21FBP22 with separate safety glass.

Logically that glue would also help keep at least some glass from flying. If the glue is new it could even make a huge difference.

I suspect the non-laminated safety glass would not stop any glass from flying. I think the non-laminated safety glass is simply to help anything hitting the CRT directly.

[QUOTE=peverett;

I also have a 1963 Ford Falcon-no fan shield on this model (as well as a solid steel steering column). One of my mother's brothers was killed by a car with no fan shield-the fan flew apart as he was working on it and hit him in the head.

In general, safety is a much higher priority in things built today.[/QUOTE]



Where have I read about the Falcon's safety issues in here? Seems like some brash and sassy writer claimed the Falcon is extremely unsafe only to be punished for doing so.

[RetroHacker]

Originally Posted by Brach

Logically that glue would also help keep at least some glass from flying. If the glue is new it could even make a huge difference.

That's just the thing - when a tube with cataracts gets repaired, the safety glass doesn't get glued back onto the tube. It's impossible to get it glued on and have it be perfectly clear. Typically the glass just gets taped around the edge of the tube with packaging tape.

I actually don't think it would be any more or less safe this way. In a way, it may even prevent glass from flying out - instead of an imploding tube simply breaking the faceplate along with the face of the tube (because they're glued together), it would have to hit the safety glass hard enough to break it _and_ blow through it to cause harm.

But, that's really all just speculation. I have no real clue which is safer. As others have pointed out, safety wasn't a prime concern back then. And yet we're all still alive...

-Ian