Cryogen expiry alarms

[Roland Reiss]

roger smith x294 wrote:
> 
> ccd-world,
> 
> (In response to Paul Jorden)
> 
> At CTIO we have had similar experiences and I was going to write an
> almost identical reply to that of Carter/Koorts/Evans at SAAO.
> 
> We use a neck tube which goes to the center of the flask so that hold
> time is more or less independent of orientation.  With about 18-20
> hour hold time, we fill twice a day.
> 
> There are occasional human errors or vacuum problems, so we too find
> an alarm useful.  When I have the opportunity, I glue a sensor to the
> neck tube (on the vacuum side) to sense the presence of gas flow from
> the boiloff.  Placing the sensor near the warm end provides very good

Which type of sensor do you use and how exactly do you glue it
to the tube?

-- 
*	Roland Reiss			European Southern Observatory	
*	Optical Detector Team		Karl-Schwarzschild-Str. 2
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