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Appendix B Electrochemical Sensor Cross Sensitivity Data
The table below provides the cross-sensitivity response of the Cannonball3 toxic gas sensors to common interference gases. The values are expressed as a
percentage of the primary sensitivity, or the reading of the sensor when exposed to 100ppm of the interfering gas at 20ºC. These values are approximate. The actual
values depend on the age and condition of the sensor. Sensors should always be calibrated to the primary gas type. Cross-sensitive gases should not be used as
sensor calibration surrogates without the express written consent of Sperian Instrumentation.
SENSOR
CO H
2
S SO
2
NO NO
2
Cl
2
ClO
2
H
2
HCN HCl
NH
3
C
2
H
4
C
2
H
2
Carbon Monoxide(CO)
100
10 5 10 -15 -5 -15 50
15 3 0 75 250
Carbon Monoxide (CO+)
100
350 50 30 -60 -60 -120 50 n/d n/d 0 75 250
Carbon Monoxide (CO-H)
100
10 5 n/d (-) (-) (-) 5 n/d
n/d
n/d
(+) (+)
Hydrogen Sulfide (H
2
S)
0.5 100 20
2 -20 -20 -60 0.2 0
0 0 n/d n/d
Sulfur Dioxide (SO
2
)
1 1 100 1 -100
-50 -150
0.2
n/d
n/d 0 (+) (+)
Nitrogen Dioxide (NO
2
)
-5 -8 -1 0 100 90 270 0 n/d
n/d 0 n/d n/d
Chlorine (Cl
2
)
(nonspecific)
0 -3 -1 0 110
100 310 0 n/d
n/d 0 n/d n/d
Chlorine (Cl
2
)
(specific)
0 -3 0 n/d 12 100 0 0 0 2
n/d 0 0
Chlorine Dioxide (ClO
2
)
(nonspecific)
0 -1 -0.3 0 40 33 100 0 n/d
n/d 0 n/d n/d
Chlorine Dioxide (ClO
2
)
(specific)
0 0 0 n/d n/d 0 100 0 0 0
n/d 0 0
Ammonia (NH
3
)
–21
0 <5 0 n/d 0 0 n/d 0 0 0 100
0 0
Ammonia (NH
3
) -04
0 130 70 15 -5 -50 -150 0 5 0 100
0 n/d
Phosphine (PH
3
)
0.5 25 20 n/d (-) (-) (-) 0.1 n/d n/d n/d 1 0.5
Hydrogen Cyanide (HCN)*
0.5
350 160 -5 -100
-20 -60 0.1
100
65 -5 50 n/d
n/d = no data, (+) undetermined positive, (-) undetermined negative
O
2
Sensor/CO
2
Cross Sensitivity:
The output of the O
2
sensor used in the Cannonball3 will be enhanced by approximately 0.3% of signal per 1% of CO
2
.
*Reduced sulfur gases (H
2
S and SO
2
) are considered to be HCN sensor poisons. HCN sensors are not recommended for use in areas prone to sulfur gas presence.
Summary of Contents for Cannonball3
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