At the corporation’s Mizushima plant near Okayama, pH measurement during the neutralization of strong acids is closely monitored. For this important measurement Tsutomu Ishikawa and Naoto Ogura, engineers at the plant’s Instrumentation and Engineering Department were not satisfied with the performance of the pH sensors they were using.For this reason, sensors were regularly exchanged at the plant to minimize the chance of failure in the process. But the operation cost was high and Mr. Ishikawa and Mr. Ogura needed a better solution. Specifically, they required to know in advance when a pH sensor would need to be cleaned, calibrated or replaced: “We wanted to grasp how deposits forming on the pH sensors would affect the timing of sensor maintenance and exchange.”