THE accurate measurement of pH in many processes is extremely critical as it directly impacts product quality and yield.
Conventionally, glass electrodes were used to measure pH but the possibility of breakage poses a problem especially in the food, beverage, and pharmaceutical industries.
Endress+Hauser has now developed a range of Memosens-based digital glass-free pH electrodes built around ISFET (ion-sensitive field-effect transistor) technology.
The semiconductor sensor element is embedded in a hygienically-constructed virgin PEEK (polyetheretherketone) shaft giving it a high degree of mechanical stability and no possibility of broken glass in the process.
The classical glass pH electrode has a further limitation when considering the need to mount them at an angle with the bulb at the bottom so that the electrolyte flows downwards.
Being a solid state device, Endress+Hauser's unbreakable glass-free ISFET sensor offers a much wider latitude in mounting and placement options with even upside down installation feasible - as when inserted at the bottom of a vessel.
Memosens technology provides a robust, contactless electrode-cable connection point by using an inductive electrical connection. Memosens based electrodes also feature digital memory capability, allowing them to be calibrated in the workshop at the user's convenience and stored prior to installation. As soon as the electrode is connected, the calibration data is uploaded to the transmitter automatically.
Since they are intelligent electrodes, Memosens technology hold a wealth of useful information. Partnered with the Liquiline M CM42 transmitter, users now have easy and direct access to all this data.
Apart from the pH measured value, other data includes diagnostics such as electrode status, hours in use, how many times calibrated, serial number, part number, number of times temperature exceeded, and more.
Depending on the application and the process, three electrode configurations are available.
Tophit CPS471D has a ceramic diaphragm and acrlyamide-free gel and is suitable for hygienic applications. It has a 3-A certificate, certified biocompatibility and can be used in FDA listed materials.
Tophit CPS491D is extremely dirt insensitive and resistant to blocking due to its open aperture diaphragm and is useful for process applications that include organic solvents.
Tophit CPS441D has been specially designed for extremely demanding applications including media with low conductivity. It offers the highest accuracy, incorporates a liquid reference system with a ceramic diaphragm and handles pressurisation up to 10 bar.
Since the ISFET is vulnerable to caustic soda solutions, it is advisable to use it in SIP applications or with retractable assemblies in CIP applications.