Larry,
The system has been in operation for 6 years in its present configuration. There have been no changes that we are aware of other than aging. We are thinking that somehow the tower has become insulated enough from ground and is acting like a battery or capacitor and that whatever this noise is being "stored" in the water. For the record, a hand held MYRON TDS meter is used to check calibration and its operation is unaffected. We are going to move the meter in the chiller room back outside along with its water source from the chillers. If it remains stable, that will confirm that the water is the source of the drift. In previous tests, this meter was moved to multiple locations with-in the tower yard and suffered drift despite multiple power sources including UPS clean power. This at first led us to believe we were dealing with RFI which may still be the vector fot the noise entering the water. If the meter starts to drift again under these new conditions we believe that would indicate that an RFI problem does exist and is strongest in the tower yard enclosure. The only added variable is that we have to use different, longer hoses to make the new connections. The present hoses are a white vinyl and the replacement hoses are rubber. The interior lining of the rubber hoses is black and in rubber products this could mean the presence of carbon? I couldn’t get any continuity indications with a megger so I’m hoping it doesn’t act like a wave guide. How’s that for paranoia? Thanks for all your input. It is good to bounce this off of someone else with a fresh viewpoint. I have pictures of the tower yard, power schematics etc. available if I can figure out how to post them.
Many thanks,
Jim
