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In-line Air Heaters

Certified Pre-heating Systems for Purge System Air Supply in Low Temperature Environments


  • Heats incoming air from -47°C
  • Air flow capacity up to 9,000 Nl/min
  • Two heater capacities - 2.1kW or 6.4kW
  • Local and remote low temperature alarms
  • Stainless steel enclosure construction

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  • Description
  • Specifications
  • Downloads


Expo’s low temperature motor purge and pressurization systems require compressed air supply at a temperature above -40oC. In cases where the air supply is at a lower temperature, Expo offer in-line heaters to pre-heat the purge air.

The pre-heaters are self-contained systems designed to elevate and maintain the temperature of high flows of purge system air within a specified temperature range. Air is passed through a coil of tubing, heated using self-limiting trace heating cable. This ensures that over-heating is not possible.

Switching of power to the air heater is thermostatically controlled. A second thermostat gives an alarm signal when the output air temperature drops below a pre-determined value. There is a local alarm indicator as well as volt-free contacts for remote alarm connection.



Air Inlet
Instrument quality air, 4-7 barg
System variants
2.1 kW - Flows up to 4,000 Nl/min (For use with size 3 motor systems)
6.4 kW - Flows up to 9,000 Nl/min (For use with size 5 motor systems)
Temperature range
Purge air temperature -47C
Ambient temperature range -50C to +50C
Power supply
210V to 250V AC single phase supply
Signal outputs
Low air temperature alarm
ATEX Zone 1