On 24/02/2015 11:07, 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:

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.

Where power to weight ratio and/or flameproof areas are concerned
maintenance free and fail safe is far more important than unit cost.

Aircraft, oilrigs and refineries are amongst the places where these
signs make very good sense. Flameproof electrical kit is expensive!

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Regards,
Martin Brown