Pressure Sensor And Atmospheric Pressure Reference; Figure 2-8 Pressure Sensor On Pecm Board; Figure 2-9 Atmospheric Pressure Reference For Purge - Siemens Maxum II Manual

Safety Systems - Purging
2.2 Electronics Purging System (without Automatic Purge Unit)
2.2.6

Pressure Sensor and Atmospheric Pressure Reference

The task of detecting whether purge is operating properly is performed by the Power Entry
Control Module (PECM). PECM may refer to either the PECM or PECM-DC, depending on
the Maxum II configuration. Located on this module is a pressure sensor (Figure 2-7) that
detects the pressure inside the enclosure and compares it to the pressure outside the
enclosure. If the pressure difference is not adequate (at least 1.0 inches H
the PECM sends a signal to the control processor board (either SYSCON or CIM, depending
on the device configuration) so that an alarm can be generated. The pressure sensor detects
outside pressure using a small reference tube through the wall of the analyzer (see Figure
2-8). This tube is used only for reference and air does not flow through it.
Modular Oven
(On Bottom Right of PECM-DC)
Figure 2-8 Pressure Sensor on PECM Board
Modular Oven (Inside Side Panel)
Figure 2-9
24
Atmospheric Pressure Reference for Purge
Airbath/Airless Oven
(Not Visible When PECM is Installed)
Airbath/Airless Oven (On Back)
Manual, August 2017, A5E02220442001 Rev 8
O or 0.25 kPa) then
2
Explosion Protection Safety Standards