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Ex p Control unit
APEX
py
3 Product description
General information
Ex p control units APEX
Rev. 0
The Ex p type of protection, referred to as "pressurized enclosure", is based on
the measure of purging out any explosive gases that are in a closed enclosure
and then generating and maintaining a level of pressure that is higher than that
of the ambient atmosphere. As the pressure inside the enclosure is higher as the
atmospheric pressure, it is not possible at any time for explosive gases to
penetrate the inside of the enclosure. This creates an Ex-free area in which
electrical devices that are not themselves explosion-proof can be mounted and
operated.
The APEX control units described in these operating instructions function on the
principle of "pressurized enclosure with leakage loss compensation".
Specifically, this means that an overpressure in an enclosure is maintained by
the addition of purging gas to compensate for the leakage losses from the
enclosure.
To ensure that an explosive atmosphere that has penetrated during downtimes
cannot become a hazard, the enclosure must be flushed with purging gas
(compressed air or inert gas) before commissioning. The quantity depends on the
inspection carried out during initial commissioning. The rate of flow is measured
or determined at the outlet of the pressurized enclosure.
Since a safe state in the enclosure is only reached when the operation phase is
started, it is necessary to use explosion-proof versions of the APEX control unit
with its system components.
enclosure are enabled by the control unit APEX directly or by an additional
switching device.
Once the control unit APEX, the purging gas valve and the pressure monitor have
been mounted on the pressurized enclosure and after connection of mains
voltage and purging gas, the pressurized system starts automatically.
The control unit APEX regulates the purging gas flow and the pressure inside the
enclosure during the purging phase. When the operating phase is initiated, the
APEX control unit automatically activates the zone 2/22 certified components
mounted in the pressurized enclosure.The pressure inside the pressurized
enclosure is maintained automatically during the operating phase and any
leakage losses are compensated
01-37A2-7D0006_py_Manual_Exp-Control-Unit_20210923_a_en.docx
The control unit APEX with its system components is an
automatic controller for monitoring, controlling and
regulating pressurized enclosures in the hazardous
areas of Zone 1 and Zone 21.
The control unit APEX is suitable for all standard
applications for pressurized enclosures of Zone 1 and
Zone 21.
The electrical installed parts inside the pressurized
Product description
Page 19 of 96
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