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

Low Temperature Motor Purge & Pressurization Systems (Models D660/D760/D860)

IECEx, ATEX & INMETRO Certified Purge and Pressurization Systems for Electrical Machines in Very Low Temperature Environments


  • Certification to -60°C
  • Purge flow capacity between 1,000 and 14,000 Nl/min
  • Stable machine pressure with CLAPS technology
  • Stainless steel enclosure construction

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  • Description
  • Specifications
  • Downloads
  • Certificates
  • 3D Models


Building on the range of motor purge and pressurization systems for standard temperature, Expo have developed special systems for low temperature service as low as -60oC ambient.

The range comprises 3 systems with fow capacities between 1,000 and 14,000 Nl/min.

Each system comprises the Control Unit (CU) and the Relief Valve (RLV). The Control Unit has two compartments – one is insulated and heated and contains the control logic system, while the other is unheated and contains the main air control components, which are rated for use at very low temperatures.  Key points within the CU are fitted with RTDs to provide temperature monitoring. The RLV measures purge flow at the outlet and provides over-pressure protection for the machine.

Like all other Expo motor purge systems, these low temperature units incorporate Expo’s Closed Loop Automatic Pressurization System (CLAPS).

If the purge air supply is below -40oC then Expo recommend the use of an in-line air heating system.


Temperature range
Ambient: -60°C to +55°C
Purge air: -40°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 Connection: Ex e junction box
Temperature monitoring
2 RTDs for logic air temperature and logic compartment temperature.
Standard supply: Non-redundant; Connection via IS barriers
Optional supply: Dual redundant; Certified (Ex e)
System variants
D660: Purge flow up to 1,000 Nl/min
D760: Purge flow up to 6,000 Nl/min
D860: Purge flow up to 14,000 Nl/min
Power supply (Ex heater)
110/240VAC 6A

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