IECEx, ATEX & INMETRO Certified Purge and Pressurization System for small to medium sized Electrical Machines

  • Global approvals
  • Purge flow capacity up to 1,500 Nl/min
  • Stable machine pressure with CLAPS technology
  • Stainless steel enclosure construction
  • Temperature range -20°C to +55°C


The D818 purge and pressurization system delivers purge flowrates up to 1,500 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 D818 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.


Air Inlet Instrument quality air, 5-8 barg
Purge flow rate User selectable: 1,000 & 1,500 NI/min.
Leakage compensation capacity Up to 500 NI/min
Temperature range -20°C to +55°C
Purge timer 1-99 minutes
Timer power source IS (Intrinsically Safe) Battery or Electro-Pneumatic Power Supply (EPPS)
Signal Outputs Function: Power interlock, low pressure alarm, intermediate pressure alarm, purge in progress (optional)
System variants
  • D818 – Ex e junction box
  • D829 – With purge inhibit facility / fan running contacts
Certifications* IECEx, ATEX, INMETRO, EAC

* Not all certifications apply to all system variants. Check the specific Operating & Maintenance Manual for details.

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