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60
Placement and calibration of sensors
Cross sensitivity
The sensors are based on well established electrochemical sensor
technology. They are designed to be maintenance free and stable
for long periods of use.
Cross sensitivity
The following table illustrates the cross-sensitivity to a range of
commonly encountered gases, expressed as a reading of the sensor
when exposed to 100 ppm of the interfering gas at 20ºC.
Gas
CO
CO
100
H
S
<2
2
NO
-5
2
NO
0
HCN
N/D
NH
0
3
*O
-8
3
*Continuous exposures at ppm level over more than 30 minute might blind the sensor.
Table 4-1: Cross-sensitivity table of interfering gas
How sensors operate
Power is automatically applied to the gas sensors when they are
connected and the instrument is turned on. These are also referred to
as "intelligent-sensors". Additionally, the EVM will automatically identify
the type of gas sensor that is installed.
stabilize before using.
Quality calibrations
The quality of the calibration process depends upon the accuracy of
the calibration gas and allowing the sensors to stabilize before saving
the zero and span calibrations.
H
S
SO
NO
2
2
~ 7
<10
<9
~10
~1
100
<5
<-.5
0
N/D
~ 5
100
N/D
N/D
N/D
~ 60
~20
0
N/D
N/D
N/D
NOTE: it may take a few minutes for a newly inserted sensor to
Interfering Gas
NO
H
CL
2
2
2
<20
<40
N/D
~-20
~1
N/D
100
N/D
N/D
<30
N/D
N/D
N/D
N/D
N/D
~-50
<10
0
~120
~60
0
HCN
C
H
HCI
2
4
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
~-5
N/D
<10
N/D
~150
N/D
CL
O
2
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
N/D
~150
~150
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