An eductor, also known as a jet pump or Venturi pump, is a simple but clever device used to move or mix liquids, gases, or even solids, without any moving parts.
How it works (the Venturi Effect):
- Motive Fluid: An eductor uses a high-pressure "motive fluid" (typically a liquid like water or steam) that is pumped into the device.
- Converging Nozzle: This motive fluid is forced through a narrowing section called a converging nozzle. As the fluid passes through this constriction, its velocity dramatically increases, and, according to Bernoulli's Principle, its pressure significantly decreases. This is the core of the Venturi Effect.
- Low-Pressure Zone (Suction Chamber): The rapid increase in velocity and corresponding drop in pressure creates a low-pressure zone (a partial vacuum) in a chamber within the eductor.
- Suction: This low pressure then draws in a secondary fluid or solid (the substance you want to move or mix) through a separate inlet port.
- Mixing and Discharge: The motive fluid and the suctioned fluid/solid then mix together in a "throat" section and are then expelled through a diverging section (diffuser) where some of the velocity energy is converted back into pressure energy, allowing the mixed fluid to be discharged to another location.
In essence, an eductor uses the energy of a pressurized fluid to create suction, thereby moving or mixing another substance. They are valued for their simplicity, reliability (no moving parts to wear out), and ability to handle corrosive or abrasive materials.
