There seems to be a time delay factor with the reading chasing the fan speed at about a 45 second interval.
That indicates to me that the issue is not electrical, but PHYSICAL. I am guessing that the time it takes for the water to travel from the cooling tower to the sensor is about 45 seconds.
when the tower fans ramp up to maintain the temperature the conductivity reading starts to fall and vice versa.
When the water temperature changes, the concentration of the H3O+ and the OH- ions changes. That’s why pH, conductivity, & salinity probes have to be temperature compensated. When the fan speeds change, the water temperature changes.
Is downstream of the chillers a constant temperature? If so, that’s why the meter tracks actual changes in TDS.
Suggestions:
1) Test this theory by sampling the water downstream of the chiller. Then heat up and cool down the sampling line. Verify the meter readings increase with heat and decrease with cold
2) Verify the TDS meter probe temperature compensation is turned on and working.
LarryC
