Reference Gas Monitoring, Oxymat 7; Reference Gas Monitoring With Pressure Switch - Siemens SIPROCESS GA700 Operating Instructions Manual

3.4

Reference gas monitoring, OXYMAT 7

NOTICE
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.
Introduced sample gas can damage the microflow sensors, depending on the gas
composition. As long as reference gas is flowing, sample gas which could damage the
microflow sensors is prevented from reaching them.
3.4.1

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 0.1 MPa above the sample gas pressure. Only then is it guaranteed that
sufficient reference gas is flowing around the microflow sensor to be protected.
Note
Guaranteeing the function of the pressure switch
Increase the reference gas pressure until the pressure switch is triggered, i.e. the switch
contact opens. The reference gas pressure should not be more than 0.3 MPa above the
sample gas pressure.
CAUTION
Excessive sample gas pressure
If the sample gas pressure is significantly above the ambient pressure, the analyzer module
must be optimized by a service employee.
Contact the Service (Page 76).
The value when pressure is increasing (response pressure) is always higher than the value
when pressure is decreasing (release pressure). This is the switching hysteresis of the
pressure switch; it is approx. 0.06 to 0.08 MPa.
Rack-mounted device
Operating Instructions, 01/2013, A5E31874006-01
3.4 Reference gas monitoring, OXYMAT 7
Description
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