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

Description
3.4 OXYMAT 7
3.4.2.1

Reference gas monitoring with pressure switch

Note
No monitoring of measuring ability
The reference gas pressure switch only has a protective function of the microflow sensors and
is not intended to monitor the measuring ability.
Monitoring is carried out to check that the reference gas pressure is at least 1 000 hPa 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.
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 2 000 hPa above the
sample gas pressure.
Note
Excessive sample gas pressure
At the time of delivery, the pressure switch for reference gas monitoring is set to ca. 2 000 hPa
(rel.). If the sample gas pressure is increased, the reference gas pressure must be increased
accordingly. However, the monitoring function of the pressure switch would then no longer be
available.
Contact the Service (Page 144).
Have the pressure switching point of the pressure switch adjusted by a service technician or
someone trained for this scenario.
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.
32
Rack-mounted device
Operating Instructions, 05/2015, A5E31874006-03