SICK GM35

20
8009389/YN39/V3-0/2015-08| SICKOPERATING INSTRUCTIONS|GM35
Subject to change without notice
PRODUCT OVERVIEW
Cross-sensitivities with gases other than those to be measured are avoided by selecting
these evaluation ranges within the IR spectrum in conjunction with the evaluation
algorithms used (see
page 20).
2.2.2 Signal evaluation
The optimized algorithms of the GM35 evaluation electronics process the measurement
signals of the receiver elements together with the associated parameters in accordance
with the correlation procedure with optical filters for CO
2
and H
2
O and with cells filled with
gas for CO or N
2
O.
Fig. 6: Evaluation of absorption spectrums for sample gases with the GM35
CO
CO
2
H
2
O
2000 2500 3000 3500 4000
λ
[nm]
4500 50001500
18001600 2000 2200
Ref. 2 H
2
OCO
2
Ref. 1
Absorpti
H
2
OCO
2
46004400 4800 5000
CO
N
2
CO
4600 4800 4600 4800
CO
2
and H
2
O measurement in the
range of 1600–2200 nm
CO or N
2
O measurement
in the range of
approx. 4500–4900 nm
Cell wheel
N
2
/CO
Absorption CO
≈ measured value
Absorption CO
= 100%
Filter wheel for
CO
2
and H
2
O
Reference filter for determining the
background absorption, free of cross-
sensitivities with other gas components
The CO or N
2
O- measured values are
determined from the signals at the detector with
absorption by the sample gas and with a cell
filled with the component to be measured.
Interference is eliminated
Transmission
characteristic
line of the CO
measurement
filter
Absorption