Oxymat 7; Reference Gas; Zero Point Error - Siemens SIPROCESS GA700 Operating Instructions Manual

Commissioning

8.3 OXYMAT 7

8.3 OXYMAT 7
Incorrect reference gas
Explosion hazard when used in the hazardous area.
Use nitrogen exclusively as the reference gas for combustible media in the hazardous area.
Also ensure that the reference gas pressure is at least 2.2 bar (3.2 bar abs.).
8.3.1

Reference gas

Only used nitrogen as the reference gas.
Make sure that the reference gas pressure is 2000 hPa +/- 150 hPa above the sample gas
pressure.
8.3.2

Zero point error

Accompanying gases (interfering gases) cause a zero point deviation that is positive with
paramagnetic gases and negative with diamagnetic gases. The extent of this offset per 100
vol. % accompanying gas, expressed in vol. % O
values in the tables refer to nitrogen at 60 °C and 1 000 hPa absolute to IEC 1207/3.
Table 8-1
Accompanying gas (concentration 100 vol. %)
Ethane
Ethene (ethylene)
Ethine (acetylene)
1.2 butadiene
1.3 butadiene
n-butane
Isobutane
1-butene
Isobutene
Dichlorodifluoromethane (R12)
Ethanoic acid
n-heptane
n-hexane
Cyclo-hexane
Methane
Methanol
70
WARNING
Zero point error of organic gases
absolute, is listed in the following table. The
2
Zero point deviation in
vol. % O
C H
2 6
C H
2 4
C H
2 2
C H
4 6
C H
4 6
C H
4 10
C H
4 10
C H
4 8
C H
4 8
CCl F
2 2
CH COOH
3
C H
7 16
C H
6 14
C H
6 12
CH
4
CH OH
3
Operating Instructions, 05/2015, A5E35640463-02
absolute
2
-0.49
-0.22
-0.29
-0.65
-0.49
-1.26
-1.30
-0.96
-1.06
-1.32
-0.64
-2.40
-2.02
-1.84
-0.18
-0.31
Field device