Hygienic conductivity sensor.

The Memosens CLS82D conductivity sensor for production, process development and laboratory applications in the pharmaceutical, food, life sciences and other industries has been . The four-electrode sensor measures conductivity from 1 µS/cm to 500 mS/cm and temperature from 23 to 248 °F (-5 to 120 °C) with accuracy of ≤4% and repeatability of 0.2%.

For hygienic applications, the CLS82D has 316L stainless steel construction, electropolished surfaces that are easy to clean, hygienic process connections and IP68 protection, and it can be sterilized in place (SIP) at temperatures up to 284 °F (140 °C) for clean-in-place (CIP) operations. The CLS82D is certified for EHEDG, FDA, 3-A and pharmaceutical applications. Typical applications include phase separations, chromatography, fermentation, CIP, monitoring and ultrafiltration.

The sensor is available in a standard PG13.5 thread size, with 1.5 and 2 inch Tri-Clamp sanitary fittings, or with an NPT fitting, making it suitable for a variety of applications.

The conductivity measuring cell has four platinum electrodes housed in a ceramic sensor element. Similar temperature expansion behaviors of the materials ensure the material bond stays tight even during extreme temperature changes, allowing cleanability and aseptic hygiene.

During operation, an alternating current is applied to the outer electrode pair. At the same time, the voltage applied is measured at the two inner electrodes. The electrolytic conductivity between the electrodes can be reliably established based on the measured voltage and the current flow caused by the liquid's resistance. The advantage of this technology compared to traditional two-electrode sensors is that electrochemical effects at the live electrodes are suppressed by the two additional voltage measuring electrodes.

The sensor connects to an Endress+Hauser Liquiline transmitter that sends conductivity and temperature information to a process control, SCADA or monitoring system via 4-20mA HART, Profibus DP, Modbus RTU or EtherNet/IP. Liquiline transmitters also have a web server that allows the CLS82D’s output, status, diagnostics, logbooks and calibration information to be viewed on a handheld tablet, smartphone or laptop PC via a Wi-Fi or internet connection via any web browser.

The CLS82D is a digital sensor, so it can stores a variety of data in the sensor itself including serial number, data of manufacture, calibration date, number of calibrations, conductivity application range, cell constant, hours of operation at high temperatures, and other data quantifying operating history. These features allow “plug and play” compatibility with the Liquiline transmitter to simplify commissioning, maintenance and replacement—while also improving improves reliability.

For example, an existing sensor can be quickly replaced with a pre-calibrated sensor which automatically connects to the Liquiline transmitter via a non-contact digital connection, eliminating problems with moisture and corrosion. Maintenance intervals can be more efficiently determined based on stored sensor load and calibration data instead of simply on a calendar basis.

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