Scott Safety Protege, User Manual

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Gas Interferences
65
SCOTT SAFETY 087-0038 REV L
Gas Interferences
There are known gas interferences to a limited number of chemical compounds.Scott
Safety attempts to identify possible gas interferences to which gas sensors may be
exposed; however, not all chemical compounds that presently exist have been tested.
Table 20 provides known toxic gas interferences.
Table 20
does not show, nor should it be implied, that no additional interferences may
occur. these selectivity ratios are used as guides only. They are not to be used as
calibration factors. The gas species’ actual cross-sensitivities may vary from the
values shown.
Table 20 Gas Interferences
SENSOR TYPES (ALL VALUES IN PPM)
Dual-Tox Sensor
CO H
2
S CO H
2
S
Interference
Gas
CO
1
< 0.02
1
< 0.02
H
2
S < 0.04
1
< 0.25
1
SO
2
< 0.2 < 0.2 < 0.25 < 0.1
NO
2
< 0.02
~ -0.2 -0.25 to 0 < -0.3
NO < 0.003 < 0.03 < 0.5 < 0.02
NH
3
< 0.001 < 0.001
H
2
~ 0.2 0.003 < 0.6 < 0.005
CL
2
0 0 < 0.001 < -0.25
Key: < Less than; ~ Approximate.
For each sensor type, the table shows how 1ppm of an Interference Gas
appears on that specific sensor type. For example, 1ppm CO appears as less
than 0.02ppm on a H2S sensor.