Isolating the pressure sensor may be a good idea.  Even if a bubble
won't work, perhaps a long tube that is pressurized at the top with
a inert gas that slowly leaks out the bottom.  There is probably a
way to simplify turning the inert gas reservoir on and off.

What pressure does the gas pressure sensor operate at ?
Gus


> On Feb 19, 2010, at 3:59 PM, Carl Denk wrote:
>
> Don't think a bubble is applicable. The natural gas well is a 1000  
> feet
> deep, 6" diameter hole mainly in shale stone. The natural gas seeps  
> out
> of fissures and porosity of the shale. In general the hole is dry, but
> there could be water near the bottom. The top 160 feet of hole are  
> lined
> with steel casing with a coupling and plug 3 feet above ground  
> level. A
> 1.25" steel pipe is welded to the side of the casing, and there are  
> some
> valves, and a tee fitting for the pressure sensor, and a visual gauge.
> There is no liquid to bubble. :)
>
> Marcel Duchamp wrote:
>> It sounds like you are not quite sure as to whether the failures are
>> caused by ESD or damage from incompatible media.
>>
>> One type of solution that could make both cases better but is more
>> complex would be to use a bubbler system.  This prevents contact with
>> the media and can help to isolate the sensor electrically as well.
>>
>> Basically, you hang a conduit (tygon tubing, or whatever) down into  
>> the
>> location to be measured.  The top goes to a 'T' fitting that splits  
>> out
>> to your pressure sensor and a pressure source.  The source can be any
>> supply of air pressure that is slightly higher than your full scale
>> pressure to be measured.  The air pressure line has a solenoid in  
>> it so
>> you can turn it on to purge the line, shut it off, wait a bit then  
>> take
>> a pressure measurement.  The air pressure in the tubing will bubble  
>> out
>> the bottom (hence the name bubbler).  When it turns off the system  
>> will
>> return to static pressure to be measured.

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