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Michell Instruments Cermet II Hygrometer

A full specification on-line hygrometer for the measurement of dew point in air and process gases, with wide operating range and multiple display options.


  Wide measurement range, calibrated -100 to +20°Cdp
  ±1°Cdp measurement accuracy
  Pressure sensor input
  Up to 4 alarm relays
  User selectable units of measurement
  Easy to read display
  Analog and digital outputs


  Industrial gases
  Dried compressed air
  Welding gases
  Glove boxes
  Medical gases
  High voltage switchgear (SF6)

Complete On-Line Dew Point Solution - Cermet II is the intelligent choice for reliable on-line measurement of moisture in virtually any gas, across many applications. Cermet II combines Michell's Advanced Ceramic Moisture Sensor and a monitor unit that can be located up to 1200 m apart. While Cermet II is so simple to use, it has the fl exibility to be applied to almost any humidity measurement application. The instrument can display measurement units in °C or °F dew point, ppmV, lb/mmscf or g/m3 across the measurement range -100 to +20°C dew point at pressures up to 400 barg. The Cermet II also can accept a pressure signal from a pressure transmitter (optional) providing the means of active pressure compensation for concentration units of measurement.

Cermet II Monitor - The Cermet II Monitor is a fully self-contained display system in a 1/8 DIN panel mounting case that indicates the measured humidity parameter and performs pressure compensation (if required). Cermet II also provides current and digital outputs and two 10 A alarm relays. It is protected to NEMA 12 and can be supplied with an optional front panel providing a NEMA 4 rating. Its operating temperature range is -20 to + 50°C.

Cermet II Sensor - The Cermet II Sensor uses Michell's Advanced Ceramic Moisture Sensor technology with on-board intelligence. This smart sensor has a measurement range of -100 to +20°C dew point at pressures up to 45 MPa (450 barg/6500 psi) max and offers a superior measurement accuracy of better than ±1°C dew point from -60 to +20°C. From -100 to -60°C dew point the measurement accuracy is ±2°C dew point. The on-board processor in the sensor electronics enables excellent performance, reliability and interchangeability of sensors. Cermet II's sensor is designed to perform in harsh environments. Constructed in stainless steel, the sensor is also protected to NEMA 4 and has an operating temperature range of -40 to +60°C.

Extreme Flexibility - The dew point of any gas will vary with pressure. When calculating concentration units of measure, Cermet II can compensate for these variations either by using of a live pressure transducer input, or by using a pressure factor input via the instrument front panel.

For control of external devices Cermet II is supplied as with two 10 A, 240 V AC fully user confi gurable alarms as standard. These can be set over the full operating range of the instrument, with variable hysteresis for any chosen engineering unit. The alarms can also be confi gured to fl ag sensor or cable fault conditions. An additional two alarms can be added if required.

Cermet II is supplied with a 4-20 mA output, which is fully confi gurable for range and scale as standard. In addition, a 2-way RS232 digital signal is provided which gives full data access to the user. Optionally a 0-10 V confi gurable analog output can be specifi ed, as can an RS485 2-way digital output.

Applications - Cermet II can provide the solution to both energy management and quality assurance in the supply of pure gases and compressed air from heat regenerative, adsorption dryers. The durability of the Advanced Ceramic Moisture Sensor provides long term service in applications such as pipeline drying using vacuum and dry gas purging techniques.

Impedance - The Cermet II uses Impedance technology, based on Michell's advanced ceramic sensor. The operation of this sensor depends on the dielectric property of water molecules absorbing onto an active porous insulating layer sandwiched between two layers of conductive material deposited on a ceramic substrate.

Water has a very high dielectric compared to the dielectric of the active layer and the background of the carrier gas so it can be detected easily.

The active layer is very thin - less than one micron and the porous top conductor that allows water molecules to penetrate into the active layer is less than 0.1 micron thick. This allows the sensor to respond very rapidly to changes in the moisture surrounding it both when moisture decreases (drying) and increases in the sensor environment.

Data Sheet

Please note - Product designs and specifications are subject to change without notice. The user is responsible for determining the suitability of this product.

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