On Tuesday, February 24, 2015 at 11:05:47 AM UTC, charles wrote:
In article ,
Martin Brown wrote:
On 23/02/2015 21:04, Tough Guy no. 1265 wrote:
On Mon, 23 Feb 2015 10:46:47 -0000, Martin Brown
wrote:

On 22/02/2015 15:14, charles wrote:
In article , Tough Guy no. 1265
wrote:
On Sun, 22 Feb 2015 12:39:49 -0000, Jim Newman wrote:

On 20/02/2015 17:04, Tough Guy no. 1265 wrote:
On Fri, 20 Feb 2015 16:26:40 -0000, Brian Gaff
wrote:

What about the trimfones btalite gas filled tube behind the dial? I
can recall being rather appalled back in the 60s when we found my
grandfathers old alarm clock in a drawer, still glowing from dots of
something or other after 10 years. I doubt it would be adangerous
unless you strapped it to yourself for a while though.

We binned it. Brian

Unnecessarily over cautious.

So long as you don't break the glass envelope the tritium can't do you
any harm. Tritiated plastics are also used in emergency exit signage..
The beta emission at 18.6keV is pretty well matched to TV phosphors and
very few can get through even the thinnest layer of glass or plastic....

The emergency exits I've seen are lit by a battery operated lamp.

You must lead a very sheltered life. They are available in the UK.

http://www.sos-uk.co.uk/tritium-signs.html

and, how much do they cost? battery powered signs are about £15.

How hard is it to reach the sign to change the battery is possibly a consdideration and run power to maintain it.

Tritium signs require no power at all.

BTW seem to remember something about U.S. having no reactors capable of making tritium and relied on supplies from U.K. Calder Hall to maintain their supply for H bomb fuelling.

--
From KT24 in Surrey

Using a RISC OS computer running v5.18