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

[Ed Sharpe Archivist for SMECC via GreenKeys]

I tripped over the   monster  early one we had  when it  was on the garage 
floor... I stashed it ....   thing is neat  but  it does ot move when your 
toe hits it!  Ed#  P.S.  many of these  were used in mines also.
 
 
In a message dated 1/29/2015 1:30:07 A.M. US Mountain Standard Time,  
drlegendre at gmail.com writes:

Ok, makes better sense. But the question still remains, why must  it be so 
massive?  


Thirty pounds? 


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. 


On Thu, Jan 29, 2015 at 1:50 AM, Jeffrey D Angus <_jdangus at att.net_ 
(mailto:jdangus at att.net) > wrote:

On  1/29/2015 1:14 AM, drlegendre . wrote:


So  in the case of the WE set on eBay, is this phone intended to  prevent
-or- withstand an explosion - or both?

Not  so much to withstand an explosion, but to prevent one by creating
an  exposed spark in an explosive atmosphere.

The primary concerns would  be the rotary dial contacts and the cradle
(hook) switch, switching the  48 vdc (nominal) phone line voltage.




-- 
Jeff-1.0
wa6fwi
_http://www.foxsmercantile.com_ (http://www.foxsmercantile.com/)   
 


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