Imagine getting to a waterpark and finding some of the pools dirty with that green water! Not so fun, right? On the other hand, the water burning your eyes because of high chlorine levels would also be annoying. Both of these situations come from incorrect pH levels in the pools and can be avoided using a water pH meter.

pH meters play an important role in production yield and product quality in the life sciences and chemical industries. Exceeding or falling below control points can risk quality and yield and increase waste. So companies can profit from efficient and well-maintained analytical sensors.

Technicians usually conduct maintenance at measuring points with tools, control standards, and cleaning solutions. These routine tasks seldom challenge skilled staff, but newcomers and employees with minimal experience from service companies may have problems. Techs need to understand procedures and user menus to clean and adjust analytical sensors for excellent performance. The techs also must decide if the sensor will perform well enough until the next check.

Analytical sensors
Courtesy of Mettler Toledo

Regardless of who performs the maintenance, it consumes time and money. Therefore, improving reliability and reducing costs requires a balance between proper servicing and timely sensor exchange. Exchanging too soon results in high sensor costs, and exchanging too late creates process waste and possibly damage. Still, efficient maintenance and estimation of remaining sensor life creates issues for automation staff across industries.

For example, servicing a pH electrode takes 20 to 30 minutes per sensor – and that’s just cleaning and calibration! Performance evaluation and documentation might double the time. For a process with 40 analytical loops serviced once a week or twice a month, the labor cost amounts to one or more highly skilled techs. Making sensor maintenance simpler and more reliable can offer significant cost reductions and efficiency.

Digital sensors improve reliability

Digital technology takes sensor maintenance a major step ahead by integrating many transmitter functions directly into the sensor. These sensors also have a more stable signal with 100% integrity, and they carry their specific data inside a microchip. Thus, digital sensors can radically improve the maintenance of analytical loops.

Analytical sensors
Courtesy of Endress+Hauser

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Memosens digital sensor technology

Memosens is likely the most well proven and used technology globally. Besides the robust inductive coupling, the sensors provide 100% signal integrity.  The measurement signals from the analytical surfaces convert into a stable digital signal inside the sensor.

Where analog sensors fall prey to effects like humidity, electromagnetic fields, and oxidized contacts, the digital signal of a Memosens electrode stays true. When a Memosens sensor connects, it immediately starts to measure, then sends signals digitally, already set with its adjustment values.

Memosens sensors carry all sensor-specific data, process history, and electronic identity in a microprocessor inside the sensor head. Because they store current and historical data, they offer great value for maintenance staff.

Analytical sensors
Courtesy of Knick-International

Techs no longer need to perform sensor services in the field at the measuring point. They can do them in a workshop under controlled conditions and convenient schedules, reducing maintenance time from 20-30 minutes per point down to a couple of minutes.

Calibration reports and documentation

Sensor maintenance and adjustment need good documentation. Traditionally, that requires skilled techs to go out in the field with proper equipment and procedures. Because this usually involves, among other items, safety glasses and gloves in humid environments, staff usually see documentation as a burden.

‘As found/as left’ reports

A sensor checked against a known standard before and after an adjustment gives a lot of process- and sensor-relevant information. Process industries use this procedure often. Delta values before and after sensor use inform the user of the current maintenance interval’s performance. A large delta value might require more service calls. 


Automation staff often consider sensor servicing a burden. However, the reliability of measured values depends on how well techs maintain their measuring loops. And incorrect measurement values result in lower process yield, decreased product quality, and waste. Process industries must learn to improve maintenance with respect to cost and time. 

Just like waterparks do as well.

analytical sensors
Courtesy of GIPHY
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