On Sun, 4 Sep 2005, Anand Dhuru wrote:

>> Tube inside of another tube, insulated from each other, open at both ends - 
>> forms a capacitor
>
> Do the tubes themselves also have to be insulated from the fluid (beides each 
> other) being measured?
>
> Specifically if the application involves dipping the sensor in a somewhat 
> conducting medium like water?

The tubes are covered with an insulator layer (thin ptfe). There is also 
a third piece of the same device which provides reference capacitance. 
This eliminates the need to know epsilon-r (which changes with 
temperature and density).

Peter
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