Its structure is characterized by:
(1) configure an integrated ventilation system, the motor may not exist within influences the structure of dead ends.
(2) shells and pipes made from non-combustible materials, and have sufficient mechanical strength.
(3) the shell and head relative to the outside atmosphere to maintain positive pressure large enough.
(4) motor should have a safety device (for example, time relays and flow monitors) to ensure sufficient ventilation, pneumatic block must also have under voltage protection or warning device.
(5) enclosure door or cover must be interlocked with the supply device.