Reference Gas Monitoring With Pressure Switch - Siemens SIPROCESS GA700 Operating Instructions Manual

Note
Reference gas monitoring
Monitor the reference gas pressure using an internal (optional) or external pressure switch.
Interrupt the sample gas supply if the reference gas pressure is too low, and flush the sample gas
path with inert gas.
3.8.2

Reference gas monitoring with pressure switch

In the case of non-safety-relevant oxygen measurement, a pressure switch for the reference gas
monitoring is sufficient. Monitoring is carried out to check that the reference gas pressure is at
least 1 000 MPa above the sample gas pressure. As long as reference gas is flowing, sample gas
is prevented from diffusing to the microflow sensors and destroying them.
The pressure switch for reference gas monitoring is factory-set to 2 000 hPa (rel.) when
delivered.
Note
Excessive sample gas pressure
Make sure that the maximum permissible sample gas pressure of 1100 bar (abs.) is not
exceeded.
The value when pressure is increasing (response pressure) is always higher than the value when
pressure is decreasing (release pressure). This so-called switching hysteresis of the pressure
switch is approx. 200 hPa.
Field device
Operating Instructions, 05/2022, A5E35640463-07
3.8 Reference gas monitoring OXYMAT 7
Description
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