Generator stator cooled by stator water flow. Water from a tank pumped through stator coils through coolers and filters and flow measured at outlet of stator. Three dp transmitters connected to two tappings of an orifice. The water tank has nitrogen capping at 0.3bar pressure. All three flow readings should match.

Problem started when flow readings started deviating from each other. Reasons appear to be beyond the measurement system (tapping, 3/5 way valves, xmters and electronics, grounding etc)as these have been checked. Any case of gas entrapment, issues with orifice??

 

That level of response requires a review of your piping drawings and installation details. In other words, it beyond what a simple forum response can usually provide.

That said, it would appear to be a maintenance issue. You might flush out the impulse lines and refill them.