Meaning
Electrical signal in coulometric Karl Fischer titration used to maintain the chemical balance required for moisture detection. Continuous iodine generation current measures the water content in resin pellets by converting the consumed reagent into a precise mass value. It ceases once the titration reaches its endpoint and all moisture is neutralized.
Titration Mechanism
Anodes inside the reaction cell generate the chemical species needed to react with water molecules. As moisture enters the system from a heated resin sample, the continuous iodine generation current rises to compensate for the consumption of the reagent. This happens fast.
This process happens in a closed environment to prevent atmospheric humidity from skewing the results.
Measurement Accuracy
Calculating the moisture levels in engineering plastics requires precision to avoid processing defects like splay. The amount of electricity used is tied to the mass of water through a physical constant, allowing for detection down to a few parts per million. Maintaining the electrodes in clean condition prevents erratic signals that would otherwise lead to false readings.
Modern units use algorithms to subtract the background drift from the total signal. This quantification allows for the verification of resin drying before the material enters the injection barrel.
Equipment Maintenance
Buildup of sulfur or resin dust can interfere with the sensor.
