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3.3 Behaviour of the Controller during Normal Operation
In normal operation, the controller F-351 monitors and regulates the internal pressure of the EEx-p
enclosure to the setpoint value in relation to the surrounding atmosphere.
The limit values set in the factory are:
MIN: 0,8 mbar,
MAX: 15,0 mbar.
At an increased level of internal enclosure pressure (factory setting: 4.0 mbar) with regard to the
surrounding atmosphere, a mechanical valve opens automatically in the controller. This allows the
excessive internal pressure to drop. The valve closes again when the internal enclosure pressure
has again attained normal values (factory setting: 3.5 mbar).
Fig. 4: Normal operation
T1: The purge process has ended. The specified internal enclosure pressure (see Chapter 5
“Parametrizing the Controller“; here 2 mbar) is attained. The units inside the EEx-p enclosure
are activated.
T2: Normal operation begins. The internal enclosure pressure (see Chapter 5 “Parametrizing the
Controller“; here 2 mbar) is regulated at the setpoint value.
T3: The internal enclosure pressure rises.
T4: The excessively high internal enclosure pressure is released through a mechanical valve.
T5: Normal operation begins.
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