0 to 50 PSI. working pressure. Other than occasional opening  a valve, 
pressure changes are very slow, 5 psi. in  day.

I need the sensor mounted to the pipe, tubing that could fail is not an 
option.

Zero maintenance is a priority. I won't be around forever. The idea is 
that with the troubleshooting/operations manual, a plain person with a 
few wrenches and screwdrivers can maintain the equipment.

YES NOPE9 wrote:
> 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.
>>>       
>
>   
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist