Eductors (Jet Pumps or Venturi Pumps)
Overview
Eductors—also referred to as jet pumps or venturi pumps—are mechanical devices that utilize fluid dynamics to induce flow, mix fluids, or transport solid materials. Their operation is based on the Venturi principle, in which a high-pressure motive fluid is converted into high-velocity flow through a nozzle. This velocity transformation creates a low-pressure zone that entrains a secondary fluid or solid material, resulting in efficient mixing or transfer without the need for moving parts.
Operating Principle
An eductor functions by converting the pressure energy of a motive fluid into kinetic energy. When this high-velocity stream passes through the eductor throat, it entrains the suction fluid or material and mixes it within the diffuser section. The diffuser then reconverts part of the kinetic energy back into pressure, allowing the combined flow to discharge at an intermediate pressure between the motive and suction streams.
Advantages
Eductors are recognized for their:
- No moving parts, ensuring high reliability and minimal maintenance.
- Simple design, providing easy installation and long service life.
- Corrosion-resistant construction options, suitable for harsh process environments.
- Flexibility, with configurations available for liquid, gas, or solid-handling applications.
Typical Applications
1. Mixing
- Homogenizing two or more fluids, such as combining chemicals with water.
- Blending liquids and suspended solids to form uniform slurries.
2. Pumping
- Transferring liquids between vessels, pipelines, or tanks.
- Handling fluids under varying suction or discharge pressure conditions.
3. Solid Transport
- Conveying solids such as sand, gravel, or catalyst particles within a liquid stream.
4. Vacuum Generation
- Creating vacuum conditions for tank evacuation, degassing, or process venting.
Industry Applications
| Industry | Primary Use |
|---|---|
| Water & Wastewater Treatment | Chemical dosing, tank mixing, and fluid circulation. |
| Oil & Gas | Blending chemicals into drilling muds, well fluid transfer. |
| Mining | Mixing reagents in slurries and transporting solids. |
| Food & Beverage | Ingredient blending and sanitary fluid transfer. |
| Chemical Processing | Mixing and transferring reactive or corrosive fluids. |
Common Eductor Configurations
- Firefighting Foam Eductors: Introduce foam concentrate into water streams for foam generation.
- Tank Mixing Eductors: Circulate and mix tank contents to prevent stratification and sedimentation.
- Ejectors: Remove liquids from pits, sumps, or low points in process systems.
- Sand and Mud Eductors: Clean tanks, pipes, or sumps of sediment and debris.
- Steam Jet Eductors: Utilize steam as the motive fluid for pumping or vacuum creation.
Expertise and Capabilities
Northeast Controls Inc. has over 50 years of experience designing and implementing jet pump and in-tank mixing systems. The company provides solutions utilizing both eductor and propeller-type side-entry mixers, capable of servicing tanks up to one million barrels (42 million gallons) in capacity.
Northeast Controls’ jet pump specialists ensure optimal design, sizing, and installation, delivering systems that perform reliably and efficiently—right the first time.
related: pumping gases
Jet Pumps all have three connections:
MOTIVE Connection: This connection is where the power for the eductor is generated, by increasing the velocity of the motive fluid. The eductor nozzle in this section takes advantage of the physical properties of the motive fluid. Eductors with liquid motives use a converging nozzle as liquids are not generally compressible. Eductors with gas motives utilize converging-diverging nozzles to achieve maximum benefit from the compressibility of the gas. All nozzles for eductors have smooth flow paths. Flow paths with sudden steps or roughness on these high velocity surfaces cause jet pumps to operate less efficiently.
SUCTION Connection: This connection of the eductor is where the pumping action of the eductor takes place. The motive fluid passes through the suction chamber, entraining the suction fluid as it passes. The friction between the fluids causes the chamber to be evacuated. This allows pressure in the suction vessel to push additional fluid into the suction connection of the jet pump. The high velocity of the motive stream in this section of the eductor directs the combined fluids toward the outlet section of the eductor.
Discharge Connection: As the motive fluid entrains the suction fluid, part of the kinetic energy of the motive fluid is imparted to the suction fluid. This allows the resulting mixture to discharge at an intermediate pressure. The percentage of the motive pressure that can be recovered is dependent upon the ratio of motive flow to suction flow and the amount of suction pressure pulled on the suction port. The mixture then passes through the diverging taper that converts the kinetic energy back to pressure. The combined fluid then leaves the outlet.
General Performance Table
Liquid Jet Pump Table
Using Liquid as Operating Medium| Discharge Head Level - Model | Low - SL / LL | Med - ML / LM | High - HL / LH |
|---|---|---|---|
| Operating Medium | Liquid | Liquid | Liquid |
| Operating Medium Pressure Range | 15-200 PSIG | 15-200 PSIG | 15-200 PSIG |
| Nom Operating Med Pressure PSIG/ft of Discharge Head | 2.0 PSIG (SP.GR. 1.0) | 1.5 PSIG (SP.GR. 1.0) | 1.0 PSIG (SP.GR. 1.0) |
| Discharge Head Pressure Range | to 50 FT. | 40 to 80 FT. | 80 FT. or more |
| Suction Lift | to 27 FT. | to 27 FT. | to 27 FT. |
| Minimum NPSH | 3 FT. | 3 FT. | 3 FT. |
Total customer satisfaction comes from the combination of quality products purchased at a reasonable price and delivery quickly and when promised.
Jet Pumps are in stock from 1/2″ up to 3″ sizes. Jet Pumps are stocked in Carbon Steel, 316SS and Bronze. Tanks Eductors are stocked in sizes from 3/8″ up to 3″ in both Carbon Steel and 316SS. We also stock tank eductors in Polypropylene & PVDF (KYNAR) materials in sizes from 1/4″ thru 1-1/2″.
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