Product guide

Humidity and Dew-Point Instruments
© Michell Instruments 2009-2011
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Easidew Advanced Ceramic Moisture
Sensor Technology for direct trace
moisture and dew-point measurements
Michell’s Easidew transmitters and instruments are
rugged, industrial hygrometers for reliable moisture
analysis, from trace levels to ambient air conditions.
They can be used on a wide range of gases, including
hazardous area applications (fl ammable or explosive
gases), and with many corrosive gases. All Easidew
instruments use Michell’s Advanced Ceramic Moisture
Sensor technology.
The cutting edge Michell Ceramic Sensor is constructed
using state-of-the-art thin and thick fi lm techniques.
Operation of the sensor depends upon the adsorption of
water vapor into a porous non-conducting “sandwich”
between two conductive layers built on top of a base
ceramic substrate. The active sensor layer is very thin
– less than one micron (a millionth of a metre) and the
porous top conductor that allows transmission of water
vapor into the sensor is precisely engineered to nano-
technology standards, thousandths of a millionth of a
metre thick, in order to ensure precise and repeatable
measurement.
Therefore the sensor responds very rapidly to changes
in applied moisture, both when being dried (on process
start-up) and when called into action if there is moisture
ingress into a process. Despite this extreme sensitivity
to changes in moisture content, the Michell Ceramic
Moisture Sensor is incredibly rugged, due to the nature
of its construction. To protect the sensor further against
contaminants and burrs or metal shavings adhering to
the pipework it is housed in a protective HDPE guard that
keeps contaminants out but is porous to water vapor. All
Michell Easidew Ceramic Moisture Sensors give 2°C dew
point or better accuracy and excellent long-term reliability
and stability in process applications.
Relative Humidity Sensors
Michell’s H5000 and H6000 Series are capacitive humidity
sensors providing fast and accurate measurement of
relative humidity in air, gases and other environments.
Humidity Sensor Technology
The H5000 is used to control ambient environments and
is suitable for many applications. It can be used under
repetitive and prolonged conditions of high humidity
(close to saturation). Condensation or wetting do not
alter sensor performance.
The H6000 provides enhanced protection from
contamination and corrosive environments and can be
used in most applications. It can meet the requirements
resulting from diffi cult operations, such as tile, brick and
pasta drying. It is protected against chemical contents in
air and is very suitable for poultry farms or fruit/vegetable
storage environments.
Key features of the H5000 and H6000 Series sensors are:
• Suitable for high humidity levels
• Wide operating temperature range
• Withstands condensation or wetting
Operating principle
The H5000 and H6000 relative humidity sensors are
polymer fi lm capacitive devices and benefi t from
extremely fast response, low hysteresis and high long-
term stability.
Ceramic sensor tile layers
Permeable Gold film
Hygroscopic Mono-layer
Base Electrode
Ceramic Substrate
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