Understand common reasons why you may be experiencing a DIS slope error on your analyzer.
- Most Common- Sensor needs cleaned and recalibrated
- Common- pH of the water has changed more than ~0.1 pH unit
- Least Common- Sensor is old, replace sensor
DIS slope error
Cause: After calibration, the slope was not within tolerances
Suggested remedies: Check water pH, check reference measurements, check temperature (and temperature compensation), repeat calibration, change sensor
If "Slope" error message appears, first check what the slope value is. If the value lies between zero and the tolerated minimum, the sensor signal output is too low.
“Ideal slope” refers to the at-works setting. The real slope can vary from that value, depending on measuring conditions, and sensor.
A low slope can for example be the result of wrong or missing temperature compensation.
If the slope is exactly zero, there was no measuring signal during calibration. This can be caused by lack of measuring water/flow, which should additionally trigger a "DI1 - No water" alarm or no disinfectant inside
Always check the reliabilty of your DPD reference measurement
Note: The slope message remains until a new calibration yields values within the tolerances – or until somebody resets all settings to factory settings.