The D758 purge and pressurization system delivers purge flowrates up to 6,000 Nl/min and is ideal for medium to large sized Ex p electrical machines.

The system comprises the Control Unit (CU) and the Relief Valve (RLV). The Control Unit contains the pneumatic logic to monitor and control air flow, pressure and purge timing, and provides the system outputs. The RLV measures purge flow at the outlet and provides over-pressure protection for the machine.

The D758 incorporates Expo’s Closed Loop Automatic Pressurization System (CLAPS). This allows the system to detect a rise or fall of the enclosure’s internal pressure and adjust the leakage compensation rate accordingly.

Pressure variations are more likely during sudden start-up of large rotating electrical machines but can also be caused by changes in running temperature. This system has been specifically designed to maintain a stable internal pressure within the motor enclosure.

There are system variants to cover alternative alarm output connections – see Specifications & Downloads for further details.