Maintenance Switch - Siemens Maxum II Manual

Figure 2-14
2.3.5

Maintenance Switch

This device allows a user to override the power cutoff function of the APU for maintenance
purposes. This is only allowed when it has been determined that the ambient atmosphere is
safe with no flammable gases or vapors. Because operation of the analyzer without proper
purge is a potentially dangerous operation, this switch can be operated only by using a key.
The maintenance switch allows power to the analyzer to remain connected without purge
pressure. This allows qualified personnel to perform applicable maintenance operations which
require the electronics enclosure door to be open. The maintenance switch should be set to
"normal" at all times unless applicable maintenance is being conducted.
The maintenance switch is equipped with an LED that indicates whether the enclosure is
properly purged (LED on), in the process of purging (LED blinking intermittently), or whether
there is a purge fault (LED blinking).
Potential ignition hazard
The maintenance switch should not be set to "maintenance" unless it has been determined
that conditions are safe and flammable gases or vapors are NOT present. The maintenance
switch should be set back to "normal" as soon as maintenance operations are complete.
Failure to observe these precautions could result in severe injury or death.
The maintenance switch for the MAA configuration is in the top right corner of the detector
compartment, below the electronics enclosure.
Explosion Protection Safety Standards
Manual, August 2017, A5E02220442001 Rev 8
Automatic Purge Control Unit (APU) shown in Airless/Airbath model
WARNING
2.3 Electronics Purging System (with Automatic Purge Unit)
Safety Systems - Purging
29