Siemens OXYMAT 64 - Influence of Interfering Gas

Description
2.4 Influence of interfering gas
OXYMAT 64
Operating Instructions, 06/2008, A5E00880383-03
15
Measuring effect
U = φ
R
– φ
M
U = U
A
+ RT/4F (ln [O
2
, air] – ln [O
2
]) (equation 1)
U Measuring effect
U
A
Asymmetry voltage (voltage if [O
2
] = [O
2
, air]
R Gas constant
T Temperature of ceramic in Kelvin
F Faraday constant
[O
2
, air] O
2
concentration in air
[O
2
] O
2
concentration
Note
Gas inlet conditions
The sample gas must be fed into the analyzer free of dust. The production of condensation
must also be avoided. Therefore, gas modified for the measurement tasks is necessary in
most application cases.
2.4 Influence of interfering gas
Table 2- 1 Examples of typical offsets caused by interfering flammable gases on a catalytically
inactive sensor
Measured component / interfering gas Offset caused by interfering gas
78 vpm O
2
/ 140 vpm CO -6.1 vpm O
2
10 vpm O
2
/ 10 vpm CO -0.6 vpm O
2
74 vpm O
2
/ 25 vpm CH
4
-0.3 vpm O
2
25 vpm O
2
/ 357 vpm CH
4
-1.1 vpm O
2
25 vpm O
2
/ 70 vpm H
2
-3 vpm O
2
5 vpm O
2
/ 9.6 vpm H
2
-0.55 vpm O
2
170 vpm O
2
/ 930 vpm C
2
H
4
-118 vpm O
2