Michell Optidew chilled mirror hygrometer range

The Optidew chilled mirror hygrometer range, from Michell Instruments, is designed to provide a fast response to changes in temperature and humidity, while also improving the drift-free accuracy of the fundamental chilled mirror technique by 25% to ±0.15°C. The mirror is resistant to corrosion from acids and other contaminants.

Users are offered three choices of sensor: single-stage cooling, dual-stage cooling and a dual-stage sensor that is designed specifically for use in harsh, demanding applications such as control of metallurgical processes. The harsh environment sensor is capable of operating in temperatures up to 120°C.

The range has two formats: the Optidew 501 wall-mounted unit and the Optidew 401 benchtop instrument. Both are available with a full colour touch screen HMI for easy local operation and interrogation. The Optidew 501 is also available as a transmitter, without a screen, for integration into a DCS or an environmental monitoring system such as the adaptive Rotronic Monitoring System (RMS). Michell additionally offers PC-based software for data capture and graphing. The transmitter version also includes a multicolour LED indicator which clearly displays the instruments’ status for operators to view locally.

The products have two 4–20 mA outputs and offer a choice of digital communications. The Optidew 501 has Modbus RTU over RS485, with an optional Ethernet connection and SD card slot for data logging. The Optidew 401 has a wider range of communications: RS485, USB and SD card data logging. Users can also choose to have an Ethernet connection if required.

Applications include environmental control for engine testing, climatic control in clean rooms and environmental chambers, and monitoring the coating process in pharmaceutical and confectionery manufacture. The Optidew 401 is also suitable for validating humidity probes when combined with a humidity generator and calibrated to ISO 17025 standards in one of Michell’s UKAS, NVLAP, JCSS or SGS accredited labs.