Emerson MicroCEM - Manual (Page 17)

Instruction Manual
748467-A
January 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Description and Specifications 1-3
Model MicroCEM
The signal generation is accomplished
with a pyroelectrical (solid-state) detector.
The detector records the incoming infra-
red radiation. This radiation is reduced by
the absorption of the gas at the corre-
sponding wavelengths. By comparing the
measurement and reference wavelength,
an alternating voltage signal is produced.
This signal results from the cooling and
heating of the pyroelectric detector mate-
rial.
Figure 1-1. Absorption Bands of Sample Gas and Transmittance of Interference Filters
T
rans
mi
ttance
(
%
)
0
1
8
36
5
4
72
90
T
rans
mi
ttance
(
%
)
0
15
3
0
54
60
75
9
0
CO
2
CO
Absorption Band
HC CO
2
CO
R
e
fer
enc
e
3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200 5400 5600
Wave Length (nm)