Instrument Air Inlet And Regulator; Figure 2-4 Instrument Air Inlet And Pressure Regulator - Siemens Maxum II Manual

Safety Systems - Purging
2.2 Electronics Purging System (without Automatic Purge Unit)
In this configuration air enters the enclosure through one of two possible paths. A pressure
sensor on the PECM determines whether the pressure inside the enclosure is higher than the
pressure outside the enclosure. If purge pressure is lost, then the PECM sends this status to
the System Controller (SYSCON) or Control Interface Module (CIM), depending on which
processor is used. The SYSCON or CIM generates an alarm message and turns on the Purge
warning light on the front door of the Maxum II analyzer. When purge is operating properly,
excess pressure is released through the pressure relief valve.
Note that PECM in the above descriptions may refer to the PECM or PECM‑DC, depending
on configuration of the Maxum II. The Type Y pressurization purging system consists of the
components described in the following sections.
2.2.2

Instrument Air Inlet and Regulator

This is a pressure regulator with air input that is connected to an instrument air source. The
regulator is necessary to prevent excess input air pressure. Depending on the configuration
of the Maxum II, the regulator may be labeled as either "Purge" or "Isothermal Oven Air" (refer
to the section of this manual regarding Isothermal Ovens for more information). The purge air
is connected to the purged electronics enclosure through two possible paths, the "normal" path
and the "fast purge" path. These flow paths are shown in figures 2-1 and 2-2 and are described
in the following section titled "Fast Purge Switch". All instrument air must be clean (free of
particulates and flammable vapors and gases) and dry.
Figure 2-4
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Instrument Air Inlet and Pressure Regulator
Explosion Protection Safety Standards
Manual, August 2017, A5E02220442001 Rev 8