Energy-efficient, reliable, low maintenance

Körting ejectors

Körting ejectors can be used in a wide range of applications. Each ejector is individually designed for its application and optimally suited for the specific use. In design, construction and manufacturing Körting draws on its extensive experience of almost 150 years in the application of ejectors in a wide variety of processes.

Select your ejector according to the available motive medium or the desired suction medium:

Jet pump, ejector, motive media pump, injector - many names, same design and working principle

A jet pump works without a mechanical drive and therefore offers high reliability in continuous operation mode. Körting jet pumps and ejectors enjoy a reputation of being particularly straightforward and robust in their functioning as well as being low in maintenance and wear. They are designed in a multitude of materials and optimised for their application purposes. The pumping effect is generated by means of a liquid or gaseous motive medium acting as energy carrier. The application field determines the shape of the flow cross-section which is designed individually dependent on the motive medium.

Sectional model of a steam jet vacuum pump

The lower sectional model shows the internal construction of a jet pump which generates a vacuum on the suction side by means of steam as a motive medium.

How does an ejector work - Sectional model of a steam jet vacuum pump
Sectional model of a steam jet vacuum pump
  1. steam chest
  2. motive nozzle
  3. head
  4. inlet diffuser
  5. outlet diffuser

A. motive flow with ptr (motive pressure)
B. suction flow at ps (suction pressure)
C. mixed flow at p (discharge pressure)

Design features and working principle of jet ejectors

The term jet ejector describes a device in which a pumping effect is achieved using a motive fluid. A jet ejector requires no mechanical drive and has no moving parts. This basic principle applies to every jet ejector in different models and ranges of application. The application determines the design of the flow section.

A steam jet ejector is illustrated below as example (steam serves as motive fluid to create vacuum). The function depends, above all, on the design of the motive nozzle (2) and of the diffuser (4 + 5). The motive fluid passes successively through these two components.

The flow section will change along this path. The pressure in the motive nozzle (2) decreases and the velocity rises. Conversely, the flow is decelerated in the diffuser (4 + 5) while its pressure increases to the discharge pressure at the outlet of the jet ejector.

The section between motive nozzle (2) and diffuser (4 + 5) has the lowest static pressure, approximately equivalent to the suction pressure ps. At this point the suction flow enters into the ejector head (3) through the suction connection B and is mixed with the motive fluid flowing with high velocity. Part of the kinetic energy is transferred to the suction flow. Motive flow and suction flow pass together - as a mixture - through the diffuser, loosing velocity and
gaining pressure. The increase from suction pressure ps to discharge pressure pd corresponds to the delivery head for the suction flow or to the pressure difference of the jet ejector. The ratio pd / ps is the compression ratio of a jet ejector.

ln a jet ejector the static pressure energy of the motive flow which cannot be directly transferred is thus converted into kinetic energy. This kinetic energy can be released to the suction flow by impulse transfer while both flows mingle. The diffuser converts the kinetic energy of the mixture consisting of motive flow and suction flow back into static pressure energy.

ln the steam jet vacuum ejector illustrated below, the critical pressure ratio is exceeded in the motive nozzle (2) (this can be recognized by the expansion of the nozzle cross-section downstream the minimum throat diameter.) The steam velocity exceeds the sonic velocity accordingly. Motive flow and suction flow are mixed at supersonic velocity and then decelerated to the sonic velocity upon reaching the diffuser throat. ln the diverging section of the diffuser, the pressure finally increases to the discharge pressure pd.

Types and designations of jet ejectors

Jet ejectors are used to create vacuum, to compress gases, to convey liquids, to transport granular solids, to mix liquids or gases.

The motive fluid may be:

  • steam at pressure above atmosphere
  • atmospheric steam*)
  • vacuum steam*)
  • compressed gas or air
  • atmospheric air
  • water or other available liquids

*) provided that the discharge pressure of the jet ejector or ejector stage in question is low enough.

The following table summarizes the terms of jet ejectors laid down according to DIN standards 24290. When defining certain types of jet ejectors, the standard terms for motive fluid and material delivered (gas, steam, liquid, solids) can be replaced by specific ones..

  motive medium contributing to designation gas jet ejector steam jet ejector liquid jet ejector
suction medium contributing to designation        
jet gas ejector jet ventilator gas jet ventilator steam jet ventilator liquid jet ventilator
  jet compressor gas jet compressor steam jet compressor
liquid jet compressor
  jet vacuum ejector gas jet vacuum ejector steam jet vacuum ejector liquid jet vacuum ejector
jet liquid ejector

gas jet liquid ejector steam jet liquid ejector liquid jet liquid ejector
jet solids ejector

gas jet solids ejector steam jet solids ejector liquid jet solids ejector


Recommendation for sound insulation of jet ejectors

General points

The methods described below for insulating jet ejectors, condensers, sound absorbers and pipes are merely suggestions. With this type of insulation, we expect a reduction in noise emissions of about 20 dB(A). Insulate both the pipes connected and the jet ejector.

If specifications guarantee particular sound pressure levels, insulation thicknesses have to be calculated individually. If required, we can give you a quote for carrying out the work involved.

Insulation structure

The materials described below apply to all sound insulation of jet ejectors, condensers, pipes and sound absorbers. We recommend mineral wool as the insulating material with a maximum bulk density of 140 kg/m3 (when fitted) in the form of mats and/or pipe sleeves. The thickness of the insulation layer must be at least 60 mm. The layers of mineral wool are covered with galvanised sheet steel that should be < 1.5 mm. Apply a sound insulation layer 3 mm thick to the inside of the sheet steel jacket. The sound insulation layer must comply with the following physical specifications:

  • Bulk density > 1000 kg/m3
  • Multiply the loss factor and elastic modulus < 109 N/m2 for a temperature range of 0° C to 60 °C.

Ensure that the sound insulation layer and the steel jacket are securely bonded with one another. When apply sound insulation to jet ejectors, condensers, elbows and silencers, ensure that no rigid bonds occur between the metal jacket on the exterior and the pipe- or containerwalls. In particular, do not use any spacers. Figures 1 to 3 show the structure of the insulation concerned. Sound insulation is also added to the flange and fittings. Figures 4 and 5 give examples of the types of insulation.

Figures and examples

1. Sound insulation on a pipe branch

Jet ejector sound insulation on a pipe branch


2. The end of a sound insulation section on the floor of the pipe or container

Jet ejectors the end of a sound insulation section on the floor of the pipe or container


3. Sound insulation with a continuous pipe- or container-wall with an end piece

Jet ejectors sound insulation with a continuous pipe- or container-wall with an end piece


4. sound insulation flanges

Jet ejectors sound insulation flanges


5. Sound insulation fittings and accessories

Jet ejectors sound insulation fittings and accessories


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