Edgetech Instruments 200M Data sheet

ISO/IEC 17025:2005 Accredited

ISO 9001:2008 Registered

The Edgetech Instruments Model 200M is a complete

instrument for the measurement of atmospheric
dew/frost point, ambient temperature, percent
relative humidity, or other psychometric variables.
It employs the very reliable chilled mirror sensing
technique which provides a primary measurement
of dew/frost point temperature. Its accuracy

certification is traceable to NIST.

The Model 200M is ideally suited for installations requiring
continuous, automatic, and unattended measurement of
hu midi ty ove r a very wide range. It is ty p ical l y use d in
applications requiring precise environmental monitoring of
atmospheric conditions.

Its Automatic Balance Control (ABC) cycle corrects the light
reducing effects of mirror contaminants and allows for continuous
monitoring and virtually maintenance-free operation. This is the
first chilled mirror technology to truly reduce the need for
mirror cleaning by the incorporation of self diagnostics, which
indicate to the user, locally via an LED light source and
remotely via a logic level TTL signal, when and if maintenance
is required.

The Model 200M consists of a motor-aspirated, thermally
shielded enclosure for the dew/frost point and ambient
temperature sensors, an environmentally suited microprocessor
based electronic control unit with psychometric parameter
computing circuitry and 25 feet of interconnecting cable. The
200M measures dew/frost point in degrees C or degrees F.

Dew/frost point temperature measurement is made using a
direct measuring sensor utilizing a two stage Peltier
cooled chromium plated mirror, automatically held at
th e dew/fros t poin t temp erat ure by a photosen sing,
condensate detecting, optical system incorporating an LED
light source and photodetector. As condensate forms on the
mirror, the optical sensing bridge detects the change in light

level that occurs when dew or frost forms and develops a

proportional control signal that modulates the thermoelectric
cooler current. This control scheme permi ts the mirror to
continuously track the dew/frost point. It is a primary method
of determining the dew/frost point and hence the water vapor
content of the gas. The mirror temperature represents the true
de w/fr ost poin t t e mpe ratu re and is measur ed by an
embed d ed pr ecisi on pl atinu m res i stance th ermo mete r.
Below 0 °C, the system tracks the frost point.

All Edgetech Instruments dew/frost point hygrometers are

manufactured and supported in the USA in a modern, ISO
9001:2008 register ed f acilit y with ISO/IEC 17025:2005
accredited calibration laboratory. The 200M is delivered with a
NIST traceability certificate.

Meteorological Humidity System

Features:

• Primary measurement technique

• High accuracy and reliability

• Certificate of traceability to NIST provided

• Sensing scheme discriminates between dew/

frost and contamination

• Reduces maintenance requirements

• No drift, no hysteresis

• Fast response

• No sensor calibration required

• Self-diagnostics and continuous unattended

operation

• No balancing or other adjustments required.

Applications:

• Nuclear power plants

• Power and process industries emissions

monitoring

• External testing facilities

• Test tracks

The Edgetech Instruments 200M

Toll Free: 800-279-3729 Ph: 508-263-5900 Fax: [phone]

E-mail: [e-mail]

Web: www.edgetechinstruments.com

Technical Specifications

ISO/IEC 17025:2005 Accredited

ISO 9001:2008 Registered

Sensor Type:

Primary method, thermoelectrically cooled, chilled

mirror dew/frost point temperature sensor

D2 with two stage cooling

Measurement Ranges:
Dew/Frost Point:

-40 to 50°C (-40 to 122°F)
at 25°C ambient,
Dew/Frost Point Depression:
65°C (117°F),

Ambient Temperature:

-50 to 50°C (-58 to 122°F)
Temperature sensor (platinum resistance

thermometer): 100 ohms at 0°C

Relative Humidity:
Approximately 1% to 95%

Accuracy:

Dew/frost point, ±0.25°C (±0.5°F)
Ambient temperature, ±0.25°C (±0.5°F)
Relative humidity, ±1.0 to 1.5%

Rev v4

Outputs:

0-5 Vdc or 4-20 mA over dew/frost point span,

TTL compatible clean mirror signal

Power:

90-260 Vac, 50-400 Hz, 40 watts maximum,

RFI and line surge protection provided

Options:

Ambient temperature kit
Humidity computer (% RH or other

psychometric variables)

Air flow switch (to monitor presence or

absence of flow through the aspirator)
Signal output relay contact closure
Analog outputs, consult factory for list of

available output options

Relay contact closure for clean mirror signal
Interconnecting cable (over 25 ft.)