Zirkon® DIS and Zirkon® DIS TCL sensors are stored and shipped in a 3M KCl solution. In the presence of oxygen the 3M KCl solution will crystallize, creating an invisible barrier between the metallic measuring electrodes and the analyzer water sample.
It is strongly recommended that all disinfectant sensors (NEW and OLD) be manually cleaned with a wet paper towel with a small amount of abrasive detergent like Ajax or Comet and thoroughly rinsed before installation OR any calibration.
Example
The below image shows a Zirkon® DIS calibration results of a sensor calibrated without initial cleaning (7.2 mV/0.10 mg/L) and a calibration after manual cleaning (16.5 mV/0.10 mg/L). The first calibration produced sluggish and nonreactive response to chlorine concentration fluctuations (as expected). The second calibration is more fitting to the expected and ideal calibration expected at factory.
Upon clean and proper calibration the ASR® automatic sensor cleaning technology is then intended to keep the sensor clean.
Note - 3M KCl solution is commonly used for all pH and ORP sensors and is widely available.
Check out these helpful articles:
Setting Krypton® Multi ASR® Cleaning Frequency
Setting Krypton® DIS ASR® Cleaning Frequency