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Operation
Pressure parameter
7.13.2.1 po – Operating overpressure
7.13.2.2 p1 – Minimum pressure (Ex-relevant)
7.13.2.3 p2 – Pre-alarm
7.13.2.4 p3 – Purge pressure (Ex relevant)
7.13.2.5 p4 – Maximum pressure operation
7.13.2.6 p5 – Maximum purging pressure
Page 58 of 96
The value "po" is the internal operating overpressure of the pressurised
equipment.
This value is monitored by the Ex p control unit and compensated, if necessary.
By default, the operating pressure for the digital purging gas valve is set to 2.5
mbar.
The APEXmpc is equipped with proportional valve technology to compensate for
any leakage. The proportional valve adjusts the internal pressure of the
enclosure to the set point of "po". This is done by controlling the proportional
purge gas valve through the APEXmpc in such a way that only the occurring
leakage losses are compensated.
The value "p1" is the minimum pressure of the pressurised enclosure. This value
is safely monitored by the Ex p control unit. If the pressure falls below this value,
the pressurised enclosure is switched to the "safe state" (deactivation).
The value "p2" is a pre-alarm of the internal pressure of the enclosure. This value
is monitored by the Ex p control unit. If the pressure falls below this value, it is
possible to set off an alarm via a signal relay.
The value "p3" is the purging pressure of the pressurised enclosure during the
purging operation. The measured value is the resulting differential pressure
during purging from the internal pressure of the engine and the pressure after
the orifice in the mpv. This value is monitored by the Ex p control unit during the
purging phase. If the pressure falls below this value during the purging phase,
the pressurised equipment is not released and the purging time does not elapse.
The value "p4" is the maximum pressure of the enclosure during the operating
phase. This value is monitored by the Ex p control unit. If this value is exceeded,
there is the option to set off an alarm or to cause a shutdown (safe state Ex p
equipment).
The value "p5" is the maximum pressure of the enclosure during the purging
phase. This value is monitored by the Ex p control unit. If this value is exceeded,
there is the option to set off an alarm or to interrupt the purging operation.
01-37A2-7D0003_Operating instructions_MPC_20210923_0_en.docx
Ex p control unit
Motor Purge Controller
Rev. 0
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