"Jay *******"

Another source of lead is CRTs, many of which are still in use.
They contain about 5 pounds of lead each for radiation protection,
quite a bit more than is contained in the solder in the PC boards.



** Silly comparison.

Glass does not break down in the environment.

So how would any of that lead get out ??



....... Phil

"Phil Allison" wrote in message
...

"Jay *******"

Another source of lead is CRTs, many of which are still in use.
They contain about 5 pounds of lead each for radiation protection,
quite a bit more than is contained in the solder in the PC boards.



** Silly comparison.

Glass does not break down in the environment.

So how would any of that lead get out ??



...... Phil


Apparently, in America, they crushed the glass to powder or some such to try
to prove this. I'm sure that someone from that side of the pond, knows the
details. The lead which is contained in the faceplate glass to minimise x
radiation to acceptable levels, is actually not metallic lead, but lead
oxide, and is very firmly locked into the molecular structure of the glass,
so wouldn't readily leach anyway. 5 pounds of lead is probably a bit on the
enthusiastic side on average. 'Big' tubes may contain this amount, or even a
little more, but average sized ones, and computer monitors, would probably
be around half or a little more, than that figure. LCD displays, of course,
do not require this radiation protection.

Arfa

On Fri, 04 Apr 2008 09:29:13 GMT, "Arfa Daily"
wrote:

Apparently, in America, they crushed the glass to powder or some such to try
to prove this. I'm sure that someone from that side of the pond, knows the
details.

Yep. I sorta covered the topic previously:
http://groups.google.com/group/sci.electronics.repair/msg/e60cf96df9bfb75b
http://groups.google.com/group/sci.electronics.repair/msg/16de8814c32844b5

Is this Ban Really Necessary?
A Critical Investigation of the CRT Ban
http://www.wrppn.org/hub/hub36/Is_this_ban_necessary_CRT_.pdf

The actual EPA procedure is not really specific to CRT's.
http://www.epa.gov/sw-846/pdfs/1311.pdf

Here's a summary of the CRT testing procedure and some results:
http://www.hinkleycenter.com/publications/lead_leachability_99-5.pdf
(See Methodology starting on page 7).

"Once divided, each section was reduced in size as required by EPA
SW846 method 1311, the Toxicity Characteristic Leaching Procedure.
The TCLP is the test prescribed by the U.S. EPA to determine whether a
solid waste is hazardous by the toxicity characteristic. Each division
of a tube was tested separately (i.e. the neck, funnel, and faceplate
were analyzed individually). A sample of glass, from 200 to 500 grams,
was placed in a stainless steel bowl. The glass was covered by a cloth
for protection from airborne glass, and manually crushed with a
standard hammer. Intermittently, the glass was separated through a
9.5-mm sieve and the remaining large fraction returned to the bowl for
further crushing. The remainder of the glass (that not crushed) was
saved. For the face and funnel fractions, the remaining material mass
was often large (relative to the amount crushed the test). The rest of
method 1311 was completed and the leachate was digested and analyzed
for lead using SW846 methods 3010A and 7420."

In other words, pulverize the glass and then test for lead leaching
into various pH caustics.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On Fri, 04 Apr 2008 09:29:13 GMT, "Arfa Daily"
wrote:

5 pounds of lead is probably a bit on the
enthusiastic side on average. 'Big' tubes may contain this amount, or even a
little more, but average sized ones, and computer monitors, would probably
be around half or a little more, than that figure. LCD displays, of course,
do not require this radiation protection.

Most of the x-rays emitted by CRT's come out the BACK of the tube, not
the front. The shadow mask blocks most of them. That's also why
there's much more lead in the neck of the CRT, than in the face.

This has a fairly good table of lead content in CRT's.
http://www.eiae.org/chemicals/files/EIA_CRT_5-01.pdf
From page 3:
"The average CRT for the time period 1995 to 2000,
including televisions and monitors, is an 18.63-inch
CRT with a lead content that varies from 2.14 lbs
to 2.63 lbs."
Note that this was in 2001. It's much less now.

None of the current LCD panel manufacturers use lead in their LCD
panels. Yet, the People's Republic of California insists on treating
LCD panels (pre-pay recycling fee, hazardous waste, special handling,
etc) the same way as CRT's. That's probably because they can't tell
the difference between a CRT and and an LCD. Sigh.



--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On Fri, 04 Apr 2008 22:29:24 -0700, Jeff Liebermann
wrote:

That's also why
there's much more lead in the neck of the CRT, than in the face.

Sorry. I meant to say that there's much more lead in the funnel, not
the neck.

This has a fairly good table of lead content in CRT's.
http://www.eiae.org/chemicals/files/EIA_CRT_5-01.pdf

See Appendix B for the lead content table.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

"Jeff Liebermann"

Most of the x-rays emitted by CRT's come out the BACK of the tube, not
the front. The shadow mask blocks most of them.


** How so ??

X-rays are generated at the point where maximum electron deceleration
occurs - ie as the moment they

1. Hit the colour phosphors.

2. Are intercepted and absorbed by the shadow mask while on the way
there.

In case 1, x-rays travelling towards the viewer are absorbed only by the
face glass.

In case 2, x-rays are generated on the reverse side of the shadow mask
and then travel both forward and backwards. Those travelling forwards
are absorbed by the face glass.

The face glass is many times thicker than the rest of a CRT's glass - so it
contains most of the of lead.

The shadow mask itself is made from very thin alloys sheet ( " invar " or
nickel-iron) so will not absorb x-rays to any great extent.



...... Phil






That's also why
there's much more lead in the neck of the CRT, than in the face.

"Phil Allison" wrote in message
...

"Jeff Liebermann"

Most of the x-rays emitted by CRT's come out the BACK of the tube, not
the front. The shadow mask blocks most of them.


** How so ??

X-rays are generated at the point where maximum electron deceleration
occurs - ie as the moment they

1. Hit the colour phosphors.

2. Are intercepted and absorbed by the shadow mask while on the way
there.

In case 1, x-rays travelling towards the viewer are absorbed only by the
face glass.

In case 2, x-rays are generated on the reverse side of the shadow mask
and then travel both forward and backwards. Those travelling forwards
are absorbed by the face glass.

The face glass is many times thicker than the rest of a CRT's glass - so
it
contains most of the of lead.

The shadow mask itself is made from very thin alloys sheet ( " invar " or
nickel-iron) so will not absorb x-rays to any great extent.



..... Phil



That was kinda the way I understood it too, from my old college days, but
that was a long time ago ...

Arfa

On Sat, 5 Apr 2008 17:09:39 +1100, "Phil Allison"
wrote:

"Jeff Liebermann"

Most of the x-rays emitted by CRT's come out the BACK of the tube, not
the front. The shadow mask blocks most of them.

X-rays are generated at the point where maximum electron deceleration
occurs - ie as the moment they

1. Hit the colour phosphors.

2. Are intercepted and absorbed by the shadow mask while on the way
there.
d
Yep. See the scribbling of the Coolidge Tube at:
http://en.wikipedia.org/wiki/X-ray_tube#Coolidge_tube
Note the x-rays are produced when they hit the metal anode targe (A)
and are *REFLECTED* to wherever they need to be going. The same thing
happens in a CRT. The accelerated electrons from the filament hit the
shadow mask and produce x-rays which are reflected back towards the
filament.

Also see comments on x-rays (ionizing radiation) at:
http://en.wikipedia.org/wiki/Cathode_ray_tube#Ionizing_radiation

In case 1, x-rays travelling towards the viewer are absorbed only by the
face glass.

The metal CRT shadow mask is fairly impervious to x-rays. What
electrons go through the holes in the shadow mask to light up the
phosphor dots, do not produce x-rays.

In case 2, x-rays are generated on the reverse side of the shadow mask
and then travel both forward and backwards. Those travelling forwards
are absorbed by the face glass.

Most travel backwards (reflected) which is why the funnel of the CRT
has much more lead in it than the screen.

The face glass is many times thicker than the rest of a CRT's glass - so it
contains most of the of lead.

See appendix B at:
http://www.eiae.org/chemicals/files/EIA_CRT_5-01.pdf
For a 19" CRT, the amount of lead is:
neck 0.027 lbs
funnel 2.1 lbs
panel 0.5 lbs
frit 0.079 lbs

The shadow mask itself is made from very thin alloys sheet ( " invar " or
nickel-iron) so will not absorb x-rays to any great extent.

The shadow mask is made from Invar for mechanical stability. The
alignment of the electron beam to the phosphor dots (or lines) is
critical to maintain proper convergence. The tube gets warm and
having the aperature screen drift would be a bad idea.

When I was young (and stupid), I took some sealed Polaroid ASA 3000
speed "film" sheets, attached some coins to the surface, and plastered
them all over a late 1960's vintage color TV, where I was working.
After running the TV all day, I developed the pictures, and found a
noticeable lightening around the coins. (Polaroid "film" is positive
exposure, not negative). The shadow wasn't very distinct. The "film"
on the front screen was barely exposed, while the "film" near the Hi-V
cable was more noticeable. The "film" had to be attached to the CRT
to get any kind of exposure. Those on the cabinet showed no shadows.
About the only change that this prompted in my lifestyle was to not
leave my loaded film camera on top of the TV set.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

When I was young (and stupid), I took some sealed Polaroid ASA 3000
speed "film" sheets, attached some coins to the surface, and plastered
them all over a late 1960's vintage color TV, where I was working.
After running the TV all day, I developed the pictures, and found a
noticeable lightening around the coins. (Polaroid "film" is positive
exposure, not negative). The shadow wasn't very distinct. The "film"
on the front screen was barely exposed, while the "film" near the Hi-V
cable was more noticeable. The "film" had to be attached to the CRT
to get any kind of exposure. Those on the cabinet showed no shadows.
About the only change that this prompted in my lifestyle was to not
leave my loaded film camera on top of the TV set.

My memory (which might very well be wrong) was that one of the principal
sources of X-rays was the HV rectifier. GE got into trouble over excessive
X-radiation from their HV rectifier -- though the tube was situated such
that the kids would have had to stick their feet under the set (!!!) to
receive any significant dosage.

William Sommerwerck wrote:
My memory (which might very well be wrong) was that one of the principal
sources of X-rays was the HV rectifier. GE got into trouble over excessive
X-radiation from their HV rectifier -- though the tube was situated such
that the kids would have had to stick their feet under the set (!!!) to
receive any significant dosage.

Specifically, it was a GE-made 6BK4 that caused the problem, so it ended up
in all brands of sets via repair.

I vaguely remember that it was all alpha radiation, but don't take my word
as gospel.

--
http://apnews.myway.com/article/20080331/D8VOMVT02.html
Chelsea Clinton Criticizes Bush in N.C.

Talk about "dog bites man"...

William Sommerwerck wrote:

My memory (which might very well be wrong) was that one of the principal
sources of X-rays was the HV rectifier. GE got into trouble over excessive
X-radiation from their HV rectifier -- though the tube was situated such
that the kids would have had to stick their feet under the set (!!!) to
receive any significant dosage.


Close. Most HV rectifiers were inside steel boxes, with the flyback
transformer. The HV shunt regulator was exposed on some chassis, and
were the worst source. GE made replacements with a thick, lead
impregnated synthetic rubber coating to modify TVs built with those
chassis series. Then changes were made to the entire HV system to
eliminate the HV shunt regulator on later designs.


--
aioe.org is home to cowards and terrorists

Add this line to your news proxy nfilter.dat file
* drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic.

http://improve-usenet.org/index.html

William Sommerwerck wrote:

When I was young (and stupid), I took some sealed Polaroid ASA 3000
speed "film" sheets, attached some coins to the surface, and plastered
them all over a late 1960's vintage color TV, where I was working.
After running the TV all day, I developed the pictures, and found a
noticeable lightening around the coins. (Polaroid "film" is positive
exposure, not negative). The shadow wasn't very distinct. The "film"
on the front screen was barely exposed, while the "film" near the Hi-V
cable was more noticeable. The "film" had to be attached to the CRT
to get any kind of exposure. Those on the cabinet showed no shadows.
About the only change that this prompted in my lifestyle was to not
leave my loaded film camera on top of the TV set.


My memory (which might very well be wrong) was that one of the principal
sources of X-rays was the HV rectifier. GE got into trouble over excessive
X-radiation from their HV rectifier -- though the tube was situated such
that the kids would have had to stick their feet under the set (!!!) to
receive any significant dosage.


Speaking about feet, remember the "scopes" in some shoe stores that
would show a real-time X-ray of one's wiggling feet/toes?

In article ,
says...
On Sat, 5 Apr 2008 09:47:53 -0700, "William Sommerwerck"
wrote:

When I was young (and stupid), I took some sealed Polaroid ASA 3000
speed "film" sheets, attached some coins to the surface, and plastered
them all over a late 1960's vintage color TV, where I was working.
After running the TV all day, I developed the pictures, and found a
noticeable lightening around the coins. (Polaroid "film" is positive
exposure, not negative). The shadow wasn't very distinct. The "film"
on the front screen was barely exposed, while the "film" near the Hi-V
cable was more noticeable. The "film" had to be attached to the CRT
to get any kind of exposure. Those on the cabinet showed no shadows.
About the only change that this prompted in my lifestyle was to not
leave my loaded film camera on top of the TV set.

My memory (which might very well be wrong) was that one of the principal
sources of X-rays was the HV rectifier. GE got into trouble over excessive
X-radiation from their HV rectifier -- though the tube was situated such
that the kids would have had to stick their feet under the set (!!!) to
receive any significant dosage.

The principal source of X-ray emissions on a CRT is from the electrons
hitting the slot mask immediately behind the phosphor screen face, as
well as electron impacts on the phosphors themselves..

"Principal"? Two wrongs in one word.

X-rays are exhibited whenever an electron strikes a metal surface.

Whenever? Riiggghhtt, Dimbulb.

With things like a welding arc, it is barely measurable and considered
negligible. A TV screen, however, is thousands of "arcs" at one time. It
is still fairly negligible, however.

No, HV power supplies, even those intended for use as an anode supply,
do not emit X-rays.

AlwaysWring strikes again!


--
Keith

"Jeff Liebermann"
"Phil Allison"

Most of the x-rays emitted by CRT's come out the BACK of the tube, not
the front. The shadow mask blocks most of them.

X-rays are generated at the point where maximum electron deceleration
occurs - ie as the moment they

1. Hit the colour phosphors.

2. Are intercepted and absorbed by the shadow mask while on the way
there.

( delete drivel)


In case 1, x-rays travelling towards the viewer are absorbed only by the
face glass.

The metal CRT shadow mask is fairly impervious to x-rays.


** Nonsense - the x-ray attenuation factor of thin Fe-Ni alloy is small.



What
electrons go through the holes in the shadow mask to light up the
phosphor dots, do not produce x-rays.


** Wiki disagrees.

You got a cite for that ?



In case 2, x-rays are generated on the reverse side of the shadow mask
and then travel both forward and backwards. Those travelling forwards
are absorbed by the face glass.

Most travel backwards (reflected) which is why the funnel of the CRT
has much more lead in it than the screen.


** Maybe so, but the face glass is way thicker.


The face glass is many times thicker than the rest of a CRT's glass - so
it
contains most of the of lead.

See appendix B at:
http://www.eiae.org/chemicals/files/EIA_CRT_5-01.pdf


** You must be desperate to use survey crapology as evidence.


The shadow mask itself is made from very thin alloys sheet ( " invar " or
nickel-iron) so will not absorb x-rays to any great extent.

The shadow mask is made from Invar for mechanical stability.


** Irrelevant to the point - fool.


When I was young (and stupid),


** When ???

It ain't changed.



...... Phil

On Sun, 6 Apr 2008 12:04:56 +1000, "Phil Allison"
wrote:

The metal CRT shadow mask is fairly impervious to x-rays.

** Nonsense - the x-ray attenuation factor of thin Fe-Ni alloy is small.

The x-rays are produced by the electron beam hitting the metal. One
characteristic of metals is that they have loosely bound outer
electrons. That's why metals conduct electricity. Hit the metal atom
hard enough, and one of the electrons in the inner shell gets knocked
out. The outer electron falls inward to replace the displaced
electron, emitting x-rays in the process.

What
electrons go through the holes in the shadow mask to light up the
phosphor dots, do not produce x-rays.

** Wiki disagrees.
You got a cite for that ?

Got a reference page from whatever Wiki you were reading that says
phosphors emit x-rays when pounded on by electrons?

I don't do any extra work for anyone spewing vague denunciations
without substantiation. If you claim your "Wiki" reference is more
accurate than mine, kindly supply the URL and applicable quotes.

This article has a fairly simple explanation of x-ray production from
a Scientific American article:
http://www.noah.org/science/x-ray/stong/
I have the original article somewhere in my pile of books.

See appendix B at:
http://www.eiae.org/chemicals/files/EIA_CRT_5-01.pdf

** You must be desperate to use survey crapology as evidence.

True. I picked the first reference that someone of your limited
intelligence can understand. Got anything better or more recent?

** Irrelevant to the point - fool.

I do have one simple question. Why do you feel it necessary to add
insults to your comments? It doesn't add anything of value and
certainly doesn't improve your credibility.

When I was young (and stupid),
** When ???

Late 1960's. I was working in a hi-fi and TV repair shop. A few
weeks after I plasted the CRT with Polaroid film, one of the techs
nearly died when he grabbed the anode lead of a similar TV. Digging
around the guts of an old TV without first discharging the tube is a
really bad idea.

It ain't changed.

For you, nothing ever does.

..... Phil

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote in message
...
On Fri, 04 Apr 2008 09:29:13 GMT, "Arfa Daily"
wrote:

5 pounds of lead is probably a bit on the
enthusiastic side on average. 'Big' tubes may contain this amount, or
even a
little more, but average sized ones, and computer monitors, would
probably
be around half or a little more, than that figure. LCD displays, of
course,
do not require this radiation protection.

Most of the x-rays emitted by CRT's come out the BACK of the tube, not
the front. The shadow mask blocks most of them. That's also why
there's much more lead in the neck of the CRT, than in the face.

This has a fairly good table of lead content in CRT's.
http://www.eiae.org/chemicals/files/EIA_CRT_5-01.pdf
From page 3:
"The average CRT for the time period 1995 to 2000,
including televisions and monitors, is an 18.63-inch
CRT with a lead content that varies from 2.14 lbs
to 2.63 lbs."
Note that this was in 2001. It's much less now.

None of the current LCD panel manufacturers use lead in their LCD
panels. Yet, the People's Republic of California insists on treating
LCD panels (pre-pay recycling fee, hazardous waste, special handling,
etc) the same way as CRT's. That's probably because they can't tell
the difference between a CRT and and an LCD. Sigh.



--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS



How toxic is LCD liquid crystal though ?

Phil Allison wrote:
Jay Ts wrote:

Another source of lead is CRTs, many of which are still in use. They
contain about 5 pounds of lead each for radiation protection, quite a
bit more than is contained in the solder in the PC boards.

** Silly comparison.

Glass does not break down in the environment.

So how would any of that lead get out ??

...... Phil

My apologies, it seems I had been misinformed on that
and trusted someone who thought he understood the
situation, but didn't.

Jay Ts
--
To contact me, use this web page:
http://www.jayts.com/contact.php