[GreenKeys] OT: Explosion-Proof phone on ebay...

[Sam Hallas]

drlegendre . wrote:
> Ok, makes better sense. But the question still remains, why must it be
> so massive?
> How much of what material does it take to encapsulate the otherwise
> free-air electrical contacts? I'd think a couple of lip seals, one one
> the dial shaft, one on the switch-hook shaft, would fairly well cover
> it. Apparently the strategy must be quite a bit more elaborate, but for
> the moment, the possibilities escape me.

There's an article about the design criteria for such phones at
<http://www.britishtelephones.com/t149.htm>
referring to the British design.

The case is designed to enclose any flame produced inside to prevent it 
escaping to the outside hazardous atmosphere. Note the cunning 
decoupling of the dial.

It's quite unnerving to dial. Having wound the dial up, as soon as you 
take your finger out the front plate whizzes back to normal while the 
dial inside the case pulses out.

Here's one in the Maritime Museum in the island of Jersey

Sam
-------------- next part --------------
A non-text attachment was scrubbed...
Name: P8010155.JPG
Type: image/jpeg
Size: 95600 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20150129/57580f5c/attachment-0002.jpe>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: P8010156.JPG
Type: image/jpeg
Size: 118424 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20150129/57580f5c/attachment-0003.jpe>