Siemens SIPROCESS GA700, Руководство по эксплуатации, Страница: 184 / 224

Accompanying gas (concentration 100 vol. %) Zero point deviation in
vol. % O
2
absolute
Water H
2
O -0.03
Hydrogen H
2
+0.26
Since the zero point deviations are linear, it is easy to convert to lower interfering gas
concentrations.
In the case of interfering gases with a constant concentration an interfering gas correction with
constant zero point offset can be carried out. If the concentration of the accompanying gases
changes during the oxygen measurement, a variable interfering gas correction has to be
carried out. An external concentration must be determined for each interfering gas with a
considerable zero point deviation. Its result is fed as interfering gas concentration into the
OXYMAT 7 analyzer module and the correction value is calculated constantly.
Information on interference gas correction is available in the following operating manuals:
● Operating with the Local User Interface →Table A-3 References 1 - Operating
Manuals LUI (Page 99)
● Operation with SIMATIC PDM →Table A-4 References 2 - Operating Manuals PDM
(Page 99)
8.3.3 Introduction of reference gas
Note
Composition of the reference gas
Using a contaminated reference gas may result in the reference gas throttle (capillary tube)
becoming blocked. The device is then no longer capable of measuring.
THerefore always use dust-free reference gas as far as possible (particle size < 10 μm).
● Always introduce the reference gas before beginning the measurements.
● In the case of temporary interruption of the measurements, reference gas should also
always flow. This prevents the sample gas remaining in the measuring chamber from
diffusing to the microflow sensors and possibly destroying them.
Commissioning
8.3 OXYMAT 7
Field device
72
Operating Instructions, 05/2015, A5E35640463-02