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"T Swiss Made T" or "Swiss T 25" : what does it mean ?




In order for timepieces to be read in the dark, a luminescent material is laid on the dial indexes and hands. Generally speaking, the emission of light is either of photoluminescent type (determined by a exciting luminous radiation) or of radioluminescent type (determined by the radioactivity of the material).

Timepieces featuring radioluminescent emission are mostly designed for very specific uses : military watches, professional divers watches, etc. In this case, the use of radioactive material is strictly defined by ISO 3157 Standard which allows only two types of radionucleides : tritium (3H) and promethium (147 Pm). It is important to specify that these radionucleides emit a radiation of low energy.

ISO 3157 Standard allows an optional marking for timepieces emitting less than a certain value. The marking may be made on the dial as follows :

deposits activated by tritium : T

deposits activated by promethium : Pm

On the other hand, timepieces with a higher value, such as divers' watches, must be marked as follows :

deposits activated by tritium : T 25

deposits activated by promethium : Pm 0,5

The indication "T Swiss made T" means that the watch is Swiss and contains a certain quantity of tritium that emits less than 227 MBq (7,5 mCi).The indication "Swiss T<25" means that the watch is Swiss and contains a certain quantity of tritium that emits less than 925 MBq (25 mCi).

Most of the Swiss watches use a light emission of photoluminescent type. Some of them bear the optional marking "L Swiss Made L" to indicate it.
 

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I have never seen these marking on anything I have, even the Chase-Durer with the Tritium.
What does that say?



Here is what my CD Strike Force with Tritium says...

 

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as is explained above........it is optional.....



ISO 3157 Standard allows an optional marking for timepieces emitting less than a certain value. The marking may be made on the dial as follows :
 

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tattoo chef wrote:
as is explained above........it is optional.....



ISO 3157 Standard allows an optional marking for timepieces emitting less than a certain value. The marking may be made on the dial as follows :
Oh, DOH!
 

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Great thread and i have my Uzi Ballistic on with Swiss Tritium and it has Swiss Tritium T-25 on the face, Thanks.
 
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