Specifications

79
GMM 20W CO
2
Module
for OEM Applications
INTRODUCING THE CARBOCAP
®
Vaisala's GMM 20W transmitter uses the new
silicon based CARBOCAP
®
sensor. The simple
structure and reference measurement capabili-
ties make this Single Beam Dual Wavelength
NDIR sensor extremely stable and reliable. The
GMM 20W transmitter is intended for OEM
applications related to ambient CO
2
measurement.
CARBOCAP
®
TECHNOLOGY
The structure of the diffusion aspirated Single
Beam Dual Wavelength sensor is remarkably
simple: it consists of an infrared source, a
sample cell, a tunable solid state interference
filter and an IR detector.
The tunable interference filter enables measure-
ments at two wavelengths. This means that the
reference measurements can be made without
the typical weaknesses of Dual Beam sensors.
SUPERIOR PERFORMANCE
Incorporating the new CARBOCAP
®
sensor in
the GMM 20W transmitter provides several
advantages: high accuracy and excellent
stability, negligible temperature dependence,
and reliable operation as well as a five year
recommended calibration interval. The mea-
surement accuracy of the sensor is not affected
by dust, water vapor or most chemicals. Using
the GMM 20W can result in considerable
savings in operation, maintenance and
recalibration costs, while ensuring the best
possible quality of measurement.
IR-SOURCE
SAMPLE CELL
TUNABLE
INTERFERENCE FILTER
IR-DETECTOR
SIGNAL
PROCESSING
DIFFUSION MEMBRANE
VERSATILE TRANSMITTER
The GMM 20W transmitter has several output
alternatives. In addition to the standard 0...20 mA,
4...20 mA and 0...10 V outputs, there are also two
options: a LonWorks
®
interface and a relay output.
The GMM 20W can also be equipped with an
optional LCD display unit.
In addition to the standard 0...2000 ppm measure-
ment range, the GMM 20W can be recalibrated for
0...5000 ppm, 0...10,000 ppm and 0...20,000 ppm
ranges.
GMM 20W
CARBOCAP
®
's breakthrough self-compensating
sensor technology provides superior stability,
accuracy, and temperature dependence over a
broader temperature range. There's no add-on
software fix or external software compensation.
Just excellent sensor stability - for five years!