Emerson Unimotor Serie Manuel D'installation page 11

Pressurisation controller for ATEX motors
It is the system builder's responsibility to install and use the Unimotor in accordance with the specification of
the motor and to ensure that it is part of a safe system. To assist the system builder CTDynamics has published
the following flow rate information.
Pressurisation control system.
A flow rate of 15 litres/minute and an over pressure in the motor of 35 mBar is required and these parameters
should not be exceeded by more than 25%.
At the end of the appropriate purge time the purge outlet valve of the motor should be closed so that thereafter
it is only necessary for the pressurisation control system provided by the user, to compensate for leakage. The
leakage flow rate of the pressurised enclosure must not exceed 0.5 litre/min. Ensure that the motor connectors
are sealed with the compatible cable connectors to avoid unacceptable pressure loss. Cables must be
manufactured /approved by Control Techniques. The motor can then be powered.
Users operating their facility using compressed air are required to regulate the compressed airline to operate at a
pressure of no greater than 7 Bar. The compressed air must be obtained from a clean source at a temperature of
between 10 °C and 30 °C. Users are also required to fit a pressure relief valve or a pressure regulator that is
capable of delivering at a pressure of no greater than 7 Bar should the regulator for the airline fail. This must be
fitted in the supply to the pressurisation controller. The pressurisation controller is required to regulate source
pressure down to 35 mbar.
The pressurisation controller must be capable of regulating source pressure down to an overpressure of 150 mbar
maximum. (The installer must ensure that the performance of safety devices is verified.)
The installers must select a pressurisation control system that is capable of meeting the above requirements and
that this should be accompanied by its own EC Declaration of Conformity to the ATEX Directive and should be
marked as being associated apparatus [Ex p].
In the event of an emergency shutdown the pressurisation control system should remain operational.
Clean Air
Purge time
source.
UM 75-190 10 min
FM 075-190 3.5 min
Controller
Feedback
Safety factor
applied
25%
Pi Pressure in
Motor
Pressure out
Po
7