Siemens Maxum II Manual page 33

● EPC Limits – The maximum allowable pressure to the EPC is 700 kPa (101.5 psi).
● In systems without an APU, it is possible to equip the PECM (for Airbath/Airless oven
configuration) or PECM-DC (for Modular Oven configuration) with a jumper that will disable
the purge alarm (refer to figure below). This jumper must not be used in locations where
North American Division 1 and ATEX standards apply. The jumper must not be used without
the approval of local safety personnel.
Figure 2-19
● In systems equipped with an APU, the Maintenance Switch is intended for use only during
maintenance and troubleshooting operations. It is not intended for use during normal
operation of the analyzer. This switch must not be left in the "maintenance" position after
maintenance is completed. The switch must only be used if the area is known to be non-
hazardous. In addition, local safety personnel must approve the use.
● The electronics enclosure should always be closed in normal operation. Instrument air
should be connected and left operational. All instrument air must be clean and dry (free of
particulates and flammable gases).
● During normal startup, fast purge must be allowed to blow through the enclosure, sweeping
it free of trapped vapors and gases, for at least 8 minutes. The APU, if equipped, controls
the fast purge volume and time. For systems without an APU, the fast purge time must be
controlled manually using the fast purge switch.
● For systems without an APU, pressure inside the enclosure is compared with the pressure
outside. A reference tube (see Figure 2-8) is used for this purpose. This tube must not be
obstructed. Air does not flow through this tube. The tube is intended to sample the pressure
immediately outside the Maxum II enclosure, and it should not be lengthened, shortened,
or altered in any way.
Explosion Protection Safety Standards
Manual, August 2017, A5E02220442001 Rev 8
Modular Oven
Purge Disable Jumper on PECM or PECM-DC (Shown with Alarm Disabled)
2.4 Maintenance Considerations for Purged Systems
Airbath/Airless Oven
Safety Systems - Purging
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