41
5 Maintenance
5.2.2
Test gases for the adjustment
The following test gases can be used for adjustment:
Gas
Suitable test gases for
zero point
Sensitivity
CH
4
●
Fresh air
●
Gas mixture
CO
2
●
Fresh air
●
Gas mixture
O
2
●
Gas mixture (free from O
2
)
●
100 % vol. N
2
●
100 % vol. CH
4
●
Fresh air
H
2
S
●
Fresh air
●
Gas mixture
●
40 ppm H2S
CO
●
Fresh air
●
Gas mixture
●
40 ppm CO
NH
3
●
Fresh air
●
50 ppm NH
3
C
3
H
8
●
Fresh air
●
1.00 % vol. C
3
H
8
C
4
H
10
●
Fresh air
●
1.00 % vol. C
4
H
10
C
9
H
20
●
Fresh air
●
0.3 % vol. C
3
H
8
(replacement test gas)
If more than one test gas can be used to adjust a gas, it does
not have to be adjusted with all test gases. However, adjusting
with more than one test gas increases the measurement quality.
Every gas must be adjusted separately, Except for adjustment
with a gas mixture (see Section 5.2.3 on page 42
Replacement test gases are suitable for adjustment even though
they do not contain the gas to be tested, although the adjustment
error can be up to -15 % or +30 %.
Fresh air contains 20.9 % vol. O
2
and is therefore used with ox-
ygen to adjust the sensitivity.
Propane C
3
H
8
, butane C
4
H
10
and nonane C
9
H
20
and ammonia NH
3
can only be adjusted with individual gas.
