The GDS Red Line 9000
sensor uses proven non-dispersive single beam dual-wave
length infrared principles to detect and monitor the
presence of gases. This non-poisoning sensing technique
relies on the target gas having a unique well-defined
absorption signature. This is used to identify the presence
of the target gas and is highly specific. Using a suitable
infrared source, an analysis of the optical absorption
through the gas allows the concentration of the target
gas to be determined.
GDS Technologies use a novel dual wavelength NDIR design
incorporating two filters and a matched twin element
detector. The ‘sample’ filter selects a wavelength
region absorbed by the gas to be measured while the
‘reference’ filter selects a region of no
absorption by any gas likely to be present. Gas absorption
measurement is made by electronic signal ratioing, using a dedicated microprocessor. This
technique provides unrivalled long term measurement
stability because variations of instrument signal levels,
resulting for example from source ageing or optical
contamination, are inherently compensated for, since
both the sample and reference channels will be affected
equally and therefore will not change the ratio.
All sensor driving is internal to the transmitter and
full fault monitoring of the sensor and transmitter
is continuous.
The sensor signal is used to provide a linear output
in voltage and 4-20mA format, calibration is by means
of 4 and 20mA span potentiometers with the signal being
internally linearised without the need for user adjustments.
Internal
indicators are included for designating the transmitter
status.
These include:-
Device Active
Indication of sensor source pulsing
Indication of the calibration mode
Fault diagnostics
The 4~20mA output provides a fault indication by reducing
the
output to below 3mA, with the recovery from fault condition
being automatic.
This
information relates to the device operating continuously.
The device may be calibrated for other gases.
Internal
indicators are included for designating the transmitter
status.
NDIR (duel wave-length)
