Using a liquid to entrain liquids, solids or gases

Liquid Jet Eductors

Liquid Jet Eductors (or Water Ejectors) use the kinetic energy of a motive liquid to entrain another liquid, completely mix the two, and then discharge the mixture against a counter pressure and are used in large numbers throughout industry for pumping and mixing operations.

Applications are so numerous, it is impossible to note all of them. General uses include lifting, pumping, mixing, and agitating of liquids as well as handling granular solids and slurries. Some of the typical applications can be seen below:

  • Draining flooded cellars, Emptying tanks and sumps or bunds, Pumping and mixing operations in oil treating systems
  • De-watering sand and coal barges, Introducing anti-knock fluids and colouring matter into gasoline
  • Continuous blending, Acidifying, Causticizing of oils, Mixing drilling mud, Producing emulsions
  • Pumping food products, Pumping sand and filter clay or activated carbon
  • Tank mixing, and various Proportioning operations

Liquid jet eductors consist of three basic components, namely a converging nozzle, a diffuser (or venturi), and a body to hold these parts in their relative positions and to provide a suction (or mixing) chamber. In addition, they can be equipped with accessories such as regulating spindles, snap valves and floats to control operation. When designing eductors experience is all-important to correctly design the nozzle, diffuser, and body and their relative positions as they are all highly critical and vary according to the physical properties of the liquids being handled.

As an example of eductor performance in a typical use, a 1.5 Inch Jet Eductor discharging against a 1 BarG back pressure will empty a 2 Cubic Meter water tank in less than 1 hour using water at only 4 BarG as the sole source of motive power.

Liquid jet eductors are manufactured in a variety of types and sizes as well as materials, our standard Type 264 and 266 ranges from 0.5 Inch to 6 Inch in size where as the Type 242 unit can range from 0.5 Inch up to and beyond 24 Inch. Variables such as pressure, temperature, density, required entrainment rates, and operating conditions must all be considered before determining the correct type and size of eductor to best suit to your requirements.

(Image - Type 264 Liquid Jet Eductor)

Sand and Mud Eductors

The Sand and Mud Eductors are recommended for use in pumping out wells, bore holes, pits, tanks, sumps and similar containers where there is an accumulation of sand, mud, slime or other material of a nature not easily handled by the standard eductors.

The Sand and Mud Eductor differ from standard eductors as they have an open suction port which is designed to be submerged in the material being handled, this allows the eductor to entrain relatively large solids and particles that would otherwise block a conventional eductor. Another feature of this unit are the agitating jets installed at the base of the eductor, these nozzles help to stir the material surrounding the eductor and make it fluid. This effectively means the eductor can be left buried in mud or slurry, and when operated it will begin to excavate the surrounding solids and begin pumping.

Sizes are available in 1 Inch through to 6 Inch, with sizes up to 3 Inch supplied with screwed connections as standard, for sizes 4 Inch and above flanged connection are usually supplied. Typical materials of construction are Cast Iron, Carbon Steel, Stainless Steel and Bronze, however other materials are available on request.

(Image - Type 224 Sand and Mud Eductor)

No other pumping & mixing device offers all these outstanding features:

  • Low Cost - Units are small in relation to the work they do and cost is correspondingly low.
  • Self Priming - Eductors are self-priming. They operate equally well in continuous or intermittent service.
  • No Moving Parts - Eductors are exceedingly simple and reliable. There are no moving parts to wear or break in a basic eductor. Even when equipped with accessories such as regulating spindles, snap valves, float mechanisms, they require little attention, only periodic inspection and maintenance.
  • Corrosion and Erosion Resistant - Because they can be made of practically any workable material, or coated with corrosion-resistant materials, eductors can be made highly resistant to the actions of the liquids handled or the environment in which located.
  • Safe - Eductors can be used in hazardous locations where electrically operated alternates would require explosion proofing at considerable cost.
  • Versatile - Various piping arrangements permit adapting to environmental conditions. Eductors of various types can handle granular solids, semi-solids, and slurries without contamination.
  • Automatically Controlled - Units can be adapted for automatic control by means of a pressure liquid regulating spindle or a snap-valve and float arrangement.
  • Perform Double Duty - Eductors mix motive and suction liquids intimately while pumping against a counter pressure.
  • Easy to Install - Connections can be made to suit your piping requirements. Little space is required to accommodate units and they are normally so light in weight they can be supported by the piping to which they are attached.

Typical Eductor Applications

A few of the primary applications where eductors are used can be seen below, this list is by no means exhaustive as their uses are numerous.

Pumping & Lifting

Water jet eductors are often used to empty tanks or to pump out sumps, bunds and cellars. The motive line should be fitted with a regulating valve and a pressure gauge while the suction line should be fitted with an strainer or mesh to prevent large particles entering the unit and causing blockages. Care should also be taken to ensure the discharge lines are always sealed to prevent air leaking back towards the eductor. To accomplish this either fit a U-bend to the discharge line, or always keep the open end of the discharge pipe submerged as this will allow stable and rapid entrainment of the suction liquid.

Where possible it is recommended that the eductor be installed a short distance above the liquid to be entrained and that short suction lines be used, however eductors will operate equally well with long suction lines. Care should be taken with suction lifts greater than 4.5 meters as operating capacities are considerably reduced.

(Image - Type 264 Eductor Emptying a Sump)

Pumping Additives in to Liquids

(Image - Type 264 Eductor pumping Additives)

The eductor is being used to introduce an additive into boiler feed water. A percentage of the water flowing from the pump is bypassed into the eductor where it acts as the motive force to draw in and entrain the additive. This is the preferred method of introducing additives as it does not reduce pressure in the main line downstream of the pump, and also allows the eductor to be kept to a much more economical size.