How to tell if double glazing has "popped"...
 

Hi,

How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.
We have some 10-year-old thinnish (maybe 14mm) double glazing that seems
very cold to the touch and is getting condensation on (not in) it. One or
two of the panes have definitely gone (they have condensation inside the
unit), but if I'm going to have those replaced, I'd like to do any that are
failing too...

Is there a sonic or similar method?

Thanks

Mike

How to tell if double glazing has "popped"...
 

Mike Deblis wrote:

How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.

It doesn't have a vacuum.

The vast majority have dried air, a small percentage have argon.


We have some 10-year-old thinnish (maybe 14mm) double glazing that seems
very cold to the touch and is getting condensation on (not in) it. One or
two of the panes have definitely gone (they have condensation inside the
unit), but if I'm going to have those replaced, I'd like to do any that are
failing too...

If you're not getting condensation between the panes, the seal is intact.


--
Grunff

How to tell if double glazing has "popped"...
 

Mike Deblis wrote:
Hi,

How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.
We have some 10-year-old thinnish (maybe 14mm) double glazing that seems
very cold to the touch and is getting condensation on (not in) it. One or
two of the panes have definitely gone (they have condensation inside the
unit), but if I'm going to have those replaced, I'd like to do any that are
failing too...

Traces of water vapour in the panel may make it very, very slightly more
conductive.
But, not practically measurable.
Argon fill is (IMO) a joke - the molecular weight - and hence
conductivity is almost exactly the same as oxygen/nitrogen.
CO2 might actually be better.

IIRC, the best insulating gap is around 18mm - so you'd need at least
18+6+4 = 28mm overall. 18mm means a very thin gap - 6+4 = only 8mm or
so, which is fairly poor to start with.
Even on functioning to spec windows may well feel cold, and have
condensation in.

How to tell if double glazing has "popped"...
 

Mike Deblis wrote:
Hi,

How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.

Oops, missed this.
No double glazing has vacuum inside.
Consider a 1m^2 window - if it did, it'd have 10 tons of force pushing
each pane towards each other.
The glass would immediately shatter - if it diddn't have lots of
supports.

How to tell if double glazing has "popped"...
 

Mike Deblis wrote:
How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.

They are not evacuated units - they may be filled with
special gas, though.


We have some 10-year-old thinnish (maybe 14mm) double glazing that seems
very cold to the touch and is getting condensation on (not in) it. One or
two of the panes have definitely gone (they have condensation inside the
unit), but if I'm going to have those replaced, I'd like to do any that are
failing too...

If they're not steamed up, they're OK. 464 units which you
seem to have aren't very good insulators anyway.

I don't know of any way to test the soundness of the units.

How to tell if double glazing has "popped"...
 

On Mon, 16 Jan 2006 09:49:35 +0000 (UTC), "Mike Deblis"
wrote:

How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.

The definition of "popped" pretty much depends on whether there's
moisture inside. Although they're "sealed units", this is just
bog-standard workshop air that gets sealed into them, dried out by a
dessicator pack if you're lucky. Only the good ones have anything else
as a special filler, and even then it's still atmospheric pressure.

How to tell if double glazing has "popped"...
 

"Mike Deblis" wrote in message
...
Hi,

How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.
We have some 10-year-old thinnish (maybe 14mm) double glazing that seems
very cold to the touch and is getting condensation on (not in) it. One or
two of the panes have definitely gone (they have condensation inside the
unit), but if I'm going to have those replaced, I'd like to do any that
are
failing too...

The only evacuated tube commonplace in homes today is the TV tube, and look
at how thick the glass is on the from of that to withstand the pressure. TV
tubes are held together by a strong metal band just inside the case from the
front. If that is removed, then the whole thing will explode spectacularly
(and will have your eyes out and most of your face off - so don't even think
about experimenting).

-- JJ

How to tell if double glazing has "popped"...
 

Blueyonder wrote:

The only evacuated tube commonplace in homes today is the TV tube, and look
at how thick the glass is on the from of that to withstand the pressure. TV
tubes are held together by a strong metal band just inside the case from the
front. If that is removed, then the whole thing will explode spectacularly
(and will have your eyes out and most of your face off - so don't even think
about experimenting).


Removing the reinforcing band does not cause the immediate implosion of
the tube, and certainly not on smaller tubes. In addition, imploding a
tube is rarely as spectacular as most people who've never done it make out.



--
Grunff

How to tell if double glazing has "popped"...
 

On Mon, 16 Jan 2006 14:19:41 +0000, Andy Dingley
wrote:

|On Mon, 16 Jan 2006 09:49:35 +0000 (UTC), "Mike Deblis"
wrote:
|
|How can you (non-destructively) test double glazing to see if it had
|"popped" (lost its vacuum) without having to look for moisture inside etc.
|
|The definition of "popped" pretty much depends on whether there's
|moisture inside. Although they're "sealed units", this is just
|bog-standard workshop air that gets sealed into them, dried out by a
|dessicator pack if you're lucky. Only the good ones have anything else
|as a special filler, and even then it's still atmospheric pressure.

Except for *caravan* double glazing made of two layers of *plastic* which
are vented to the inside via a small plug. Which surprisingly works well.
--
Dave Fawthrop dave hyphenologist co uk
17,000 free e-books at Project Gutenberg! http://www.gutenberg.net
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/

How to tell if double glazing has "popped"...
 

In article ,
Ian Stirling wrote:
Mike Deblis wrote:
Hi,

How can you (non-destructively) test double glazing to see if it had
"popped" (lost its vacuum) without having to look for moisture inside etc.
We have some 10-year-old thinnish (maybe 14mm) double glazing that seems
very cold to the touch and is getting condensation on (not in) it. One or
two of the panes have definitely gone (they have condensation inside the
unit), but if I'm going to have those replaced, I'd like to do any that are
failing too...

Traces of water vapour in the panel may make it very, very slightly more
conductive.
But, not practically measurable.
Argon fill is (IMO) a joke - the molecular weight - and hence
conductivity is almost exactly the same as oxygen/nitrogen.
CO2 might actually be better.

Interestingly enough, a lot of SCUBA divers use argon to inflate their
dry suits to make them warmer. I've tried it once, and I didn't notice
any difference...

Google for argon in a scuba environment for more details... (including
holy wars by people say yes it does, not it doesn't, etc.!!!)

Gordon

How to tell if double glazing has "popped"...
 

Dave Fawthrop wrote:
On Mon, 16 Jan 2006 14:19:41 +0000, Andy Dingley
wrote:

|On Mon, 16 Jan 2006 09:49:35 +0000 (UTC), "Mike Deblis"
wrote:
|
|How can you (non-destructively) test double glazing to see if it had
|"popped" (lost its vacuum) without having to look for moisture inside etc.
|
|The definition of "popped" pretty much depends on whether there's
|moisture inside. Although they're "sealed units", this is just

Except for *caravan* double glazing made of two layers of *plastic* which
are vented to the inside via a small plug. Which surprisingly works well.

I think you mean outside - though I've never seen one.

How to tell if double glazing has "popped"...
 

On 16 Jan 2006 16:22:32 GMT, Ian Stirling wrote:

|Dave Fawthrop wrote:
| On Mon, 16 Jan 2006 14:19:41 +0000, Andy Dingley
| wrote:
|
| |On Mon, 16 Jan 2006 09:49:35 +0000 (UTC), "Mike Deblis"
| wrote:
| |
| |How can you (non-destructively) test double glazing to see if it had
| |"popped" (lost its vacuum) without having to look for moisture inside etc.
| |
| |The definition of "popped" pretty much depends on whether there's
| |moisture inside. Although they're "sealed units", this is just
|
| Except for *caravan* double glazing made of two layers of *plastic* which
| are vented to the inside via a small plug. Which surprisingly works well.
|
|I think you mean outside - though I've never seen one.

No inside, I have just looked on my van, on the drive.
Interestingly the small window on the door does not have a plug, never
noticed that before 8-0
--
Dave Fawthrop dave hyphenologist co uk
17,000 free e-books at Project Gutenberg! http://www.gutenberg.net
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/

How to tell if double glazing has "popped"...
 

On Mon, 16 Jan 2006 14:48:59 GMT, "Blueyonder"
wrote:

The only evacuated tube commonplace in homes today is the TV tube, and look
at how thick the glass is on the from of that to withstand the pressure.

TV tubes illustrate how it's easy to resist the presure, but it's the
force (pressure over an area) that causes the trouble. The big flat
screen is thick, but the small neck round the back is thin. the pressure
is the same, but only when it's a large flat area is there a problem in
supporting it.

Some houses may also have vacuum solar collector tubes. These are thin
glass and properly evacuated, but because they're only a few inches
across they're strong enough. One reason why a practical tube collector
can be evacuated and is thus more efficient than a flat plate - which is
impractical to evacuate.

How to tell if double glazing has "popped"...
 

On Tue, 17 Jan 2006 00:30:25 GMT, wrote:

There was one available once, which had a slightly undulating finish to the
glass, so the high spots touched to take the forces between the panels.

Or a cold spot, as it's also known. As conductivity of solids is
generally higher than gases (depending on how much convective transfer
there is) then even a small spot area can be less efficient than a gas
fill.

Easiest thing is to fill them gap with aerogel (as used for catching
spacedust). This has no mechanical strength so you still need the gas
fill, but it cuts out convection currents, thus dramatically reducing
the gas' normal heat loss. You lose some visibility too, but it's
surprisingly little.

How to tell if double glazing has "popped"...
 

Google for argon in a scuba environment for more details... (including
holy wars by people say yes it does, not it doesn't, etc.!!!)

Gordon

Same people who use 'oxygen free' cables on their music systems!!!

Dave

How to tell if double glazing has "popped"...
 

On Tue, 17 Jan 2006 00:32:31 GMT
wrote:

On 16 Jan,
"Blueyonder" wrote:


The only evacuated tube commonplace in homes today is the TV tube,
and look at how thick the glass is on the from of that to withstand
the pressure. TV tubes are held together by a strong metal band
just inside the case from the front. If that is removed, then the
whole thing will explode spectacularly (and will have your eyes
out and most of your face off - so don't even think about
experimenting).

ITYM implode.

Probably. There is, however, no practical difference. I've seen
high-speed films of TV tubes imploding (tests for implosion guards
back in the 1960's). The pieces are flung by the inflowing air into the
middle, where some hit one another and bounce back, and others just
keep on going. The net effect is a violent explosion where bits of glass
and the metal bits of the gun are expelled at high speed. The most
dangerous bit is the electron gun that usually flies straight out the
front where a viewer would be!

One of the reasons for the metal band is to direct any implosion - a
bit like a shaped charge for demolition.

HTH, R.

How to tell if double glazing has "popped"...
 

Richard A Downing wrote:

On Tue, 17 Jan 2006 00:32:31 GMT
wrote:

On 16 Jan,
"Blueyonder" wrote:


The only evacuated tube commonplace in homes today is the TV tube,
and look at how thick the glass is on the from of that to withstand
the pressure. TV tubes are held together by a strong metal band
just inside the case from the front. If that is removed, then the
whole thing will explode spectacularly (and will have your eyes
out and most of your face off - so don't even think about
experimenting).

ITYM implode.

Probably. There is, however, no practical difference. I've seen
high-speed films of TV tubes imploding (tests for implosion guards
back in the 1960's). The pieces are flung by the inflowing air into the
middle, where some hit one another and bounce back, and others just
keep on going. The net effect is a violent explosion where bits of glass
and the metal bits of the gun are expelled at high speed. The most
dangerous bit is the electron gun that usually flies straight out the
front where a viewer would be!

One of the reasons for the metal band is to direct any implosion - a
bit like a shaped charge for demolition.

TV sets from the 50s and 60s often had a piece of glass (perhaps
perspex ?) in front of the tube, I was always told that was a safety
screen in case of implosion, is that true ?

I did come across as a lad in the early 70s a fly tipped TV set, as any
bunch of 11 yr olds would we started to rip it apart, I recall that had
close fitting perspex around the front of the tube. Anybody know more
? The TV set tipped over, and the tube neck broke off, all there was
was a hissing sound for 10-15 seconds as the air rushed in. That by the
way is the recommended method to 'defuse' a TV tube, I've done as part
of my day job, (wearing goggles and gloves etc, and using a very long
broomhandle)

How to tell if double glazing has "popped"...
 

On 17 Jan 2006 01:42:19 -0800
"Mark Carver" wrote:

Richard A Downing wrote:

On Tue, 17 Jan 2006 00:32:31 GMT
wrote:

On 16 Jan,
"Blueyonder" wrote:


The only evacuated tube commonplace in homes today is the TV
tube, and look at how thick the glass is on the from of that to
withstand the pressure. TV tubes are held together by a strong
metal band just inside the case from the front. If that is
removed, then the whole thing will explode spectacularly (and
will have your eyes out and most of your face off - so don't
even think about experimenting).

ITYM implode.

Probably. There is, however, no practical difference. I've seen
high-speed films of TV tubes imploding (tests for implosion guards
back in the 1960's). The pieces are flung by the inflowing air
into the middle, where some hit one another and bounce back, and
others just keep on going. The net effect is a violent explosion
where bits of glass and the metal bits of the gun are expelled at
high speed. The most dangerous bit is the electron gun that
usually flies straight out the front where a viewer would be!

One of the reasons for the metal band is to direct any implosion - a
bit like a shaped charge for demolition.

TV sets from the 50s and 60s often had a piece of glass (perhaps
perspex ?) in front of the tube, I was always told that was a safety
screen in case of implosion, is that true ?

Yes, that's the 'Implosion Guard' - modern tubes (60's on) have the
implosion guard built in, which, together with the tension band, makes
them much safer. My father worked on the design of them, and
bullet-proof glass, which is why I got to see the films. I'm not an
expert really.

I did come across as a lad in the early 70s a fly tipped TV set, as
any bunch of 11 yr olds would we started to rip it apart, I recall
that had close fitting perspex around the front of the tube. Anybody
know more ? The TV set tipped over, and the tube neck broke off, all
there was was a hissing sound for 10-15 seconds as the air rushed in.
That by the way is the recommended method to 'defuse' a TV tube, I've
done as part of my day job, (wearing goggles and gloves etc, and
using a very long broomhandle)

Most tubes have a small glass 'pip' on the neck somewhere. It's said to
be quite safe to just nip it off with pliers. I don't know if this is
true, and like you, I'd only try it with full protective gear on!!!

R.

How to tell if double glazing has "popped"...
 

In article
Richard A Downing wrote:
snip

Most tubes have a small glass 'pip' on the neck somewhere. It's said to
be quite safe to just nip it off with pliers. I don't know if this is
true, and like you, I'd only try it with full protective gear on!!!

When I was a lad we knocked the neck off an old TV tube and were most
disappointed with the resulting whoosh - we were expecting something
spectacular.

How to tell if double glazing has "popped"...
 

On Tue, 17 Jan 2006 16:20:33 -0000, Rob Morley wrote:

|In article
|Richard A Downing wrote:
|snip
|
| Most tubes have a small glass 'pip' on the neck somewhere. It's said to
| be quite safe to just nip it off with pliers. I don't know if this is
| true, and like you, I'd only try it with full protective gear on!!!
|
|When I was a lad we knocked the neck off an old TV tube and were most
|disappointed with the resulting whoosh - we were expecting something
|spectacular.

When I was in the RAF, in a scare the youngsters demonstration, they put a
303 round into an old CRT, glass everywhere traveling at high speeds. I
hope the stories of improved design are true.
--
Dave Fawthrop dave hyphenologist co uk
17,000 free e-books at Project Gutenberg! http://www.gutenberg.net
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/