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Simplifying Complexity. Delivering Safety.
Simplifying Complexity.
Delivering Safety.

Purge System Interface Units (MIU/SIU)

IECEx, ATEX & INMETRO Ex d certified solutions for enclosure power and signal isolation.


  • Global Ex d approvals
  • Isolates low power signals and up to 32 A power
  • Compatible with MiniPurge & SmartPurge II
  • Aluminium construction

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Use our product configurator tool to build a system to your exact specification.


Got a question?

For more information contact your local partner to speak to one of our purge and pressurization experts or contact us.

  • Description
  • Specifications
  • Downloads
  • Certificates
  • Manuals


Expo’s Interface Units provide switching of power and signals to the pressurized enclosure, using a control signal from the purge system. This capability is required for enclosures installed in Zone 1/21 or Class I/II Div 1 hazardous locations.

2 types are available:

MiniPurge Interface Unit (MIU) – for pneumatic connection to a MiniPurge (with PO option)

SmartPurge Interface Unit (SIU) – for electrical connection to a SmartPurge

Standard units are available in 3 sizes of flame-proof / explosion-proof boxes, with a range of electrical and signal switching capacities.

Custom sizes and contents can be designed to meet specific project requirements.


Protection method
Ex d – flame-proof / explosion-proof
Power switching range
16-32A (depending on configuration)
Signal switching capacity (max)
2 off 4 pole 5A/250Vac (depending on configuration)
Cable glands
Boxes pre-drilled for approved glands
Manual override
MIU –optional key switch
SIU –SmartPurge software or optional keyswitch