Digital sensing technology provides a vast and immediate process efficiency benefit. This is especially true in critical processes that require pH for control. In these processes, two things are of utmost importance: Accuracy of the measurement and measurement “up-time”.
Losing Control with Analog Sensors
Accuracy and “up-time” can be at odds with each other when using traditional analog technology. In order to guarantee measurement accuracy, operators may need to stop the process during pH maintenance. Depending on the process, environment, and/or skill of the technician, this could be for more than 15 minutes. Most end users put the mA signal on hold during maintenance to allow the process to continue operating with the last known pH value. Depending on the nature of the process, 15 minutes of an assumed pH value can allow for “holes” in data that can lead to product quality issues.
There are two ways to overcome this problem of bad data or unnecessary process downtime.
- One way is to create measurement redundancy. Redundancy allows the user to take one measurement offline without losing the ability to still feed a good pH reading back to their PLC. The concern with this is that it simply pushes the inefficiency back to maintenance. Now you have a technician spending twice as long on maintaining one data point. He is now spending 30 minutes as opposed to 15 minutes.
- The better way is to use digital sensing technology. Using this technology allows the technician to walk out to the point of measurement with a pre-calibrated probe, hold the mA, unplug the old probe and plug in the new one in the span of a couple of minutes. Therefore, the amount of time operations is without a measurement is minimal.
Built-in Efficiency with Digital pH Sensors
The beautiful thing about this added efficiency is that the people calibrating sensors quickly learn to appreciate the new process in most facilities. As a result, technicians can spend more time fixing problems and less time watching buffers. As the industrial market becomes more aware of digital sensing technology and more comfortable with using it, this type of “invisible maintenance” (invisible to production planning) will certainly become a market requirement for process control applications. There will be no compromising up-time for accuracy.