An ejector is essentially a fluid-fluid pump that has no pistons, valves, rotors, or other moving parts and works by transfer of momentum from the primary fluid (high pressure) to the secondary fluid aspirated (low pressure).


The basic operating principle of an ejector is to convert the pressure into speed. This occurs by an adiabatic expansion of motive steam through a convergent-divergent nozzle from the motive pressure to suction pressure. The result is a supersonic speed out of the nozzle. Usually 3 or 4 Mach speeds are reached.

In operation, the motive steam expands up to a pressure below the suction pressure. This creates a depression that enters the suction load into the ejector. Motive steam at high speed is mixed with the suction flow. According to this mix enters the convergent-divergent diffuser, the speed is transformed into pressure. The convergent section of the diffuser reduces the speed, pressure shock occurs in the throat of the diffuser and divergent diffuser section increases the cross-sectional area to the flow and speed are turning into pressure energy.

Ejector systems can operate in very  in a wide range of conditions, from very light loads to loads above the value of design. An ejector system must adapt steadily to all operating conditions which may anticipate. It is essential for a stable operation the determination of the design loads of non-condensable and light loads.

Main characteristics:

  • Dynamic fluid pumps producing medium and high vacuum.
  • No moving parts.
  • No maintenance required.
  • Working with all type of fluids.
  • Reliable operation for years.
  • Installation in any position.


  • Production of medium and high vacuum.
  • Steam re-compression and gas extraction.
  • Liquids, solutions, slurries, … suction.
  • Mixing and agitation.
  • Steam saturation.

Ejector -Thermocompressor