Many customers are using conductivity to measure concentrations of bottle wash detergent. This has several advantages over titration methods, for example, the variability in results from different operators can be virtually eliminated with the conductivity technique. This is particularly true if the titration is complicated and involves more than two chemicals. Furthermore, the chemicals have to be replenished periodically and the measurement time is longer. Conductivity meters have improved considerably in design and simplicity of use, so that several types of “pocket” conductivity meters are now available at reasonable prices.
However, there are differences in quality, related to materials of construction and convenience of design. The most sensitive part of the conductivity meter is the electrode unit. If the meter is going to fail, then this will usually occur with the electrode unit. Some pocket meters have replaceable electrodes and this is a big advantage, otherwise the meter has to be returned to the manufacturer for electrode replacement.
Robustness is another important factor and the meter should be able to survive being dropped on the plant floor. Some meters are self-sampling, in other words, by dipping the meter in the wash tank sampling drawer, a sample is collected in a small cup surrounding the electrode. All these improvements come at a premium, but at the end of the day the extra investment is worthwhile. To effectively use the conductivity technique, a calibration graph needs to be drawn showing conductivity versus concentration. Your chemical supplier will be able to provide this for you.
Carry-over is another phenomenon easily measured using conductivity. All that is needed is to establish a baseline conductivity reading for “no carry-over”, your supplier will help you to do this.