The principle of a deep well pump, specifically a deep well jet pump, is the combination of two distinct pumping methods: that of the centrifugal pump and that of an injector (nozzle and venturi assembly).
Understanding the Dual Principles of Deep Well Jet Pumps
Deep well jet pumps leverage the strengths of two fundamental fluid dynamics principles to efficiently draw water from significant depths. This hybrid design allows them to operate effectively in applications where standard centrifugal pumps might struggle due to suction lift limitations.
1. The Centrifugal Pump Principle
At its core, a deep well jet pump utilizes the mechanics of a centrifugal pump. This component is typically located above ground or within the well housing.
- How it works:
- Water within the pump impeller is rapidly spun by the vanes of a spinning impeller.
- This spinning action throws the water outwards due to centrifugal force.
- This outward movement creates a low-pressure area at the impeller's center, drawing in more water, and simultaneously builds pressure at the impeller's edge, pushing water out into the discharge pipe.
2. The Injector (Nozzle and Venturi Assembly) Principle
The unique aspect of a deep well jet pump, differentiating it from a standard centrifugal pump, is the injector assembly. This part is submerged down in the well.
- How it works:
- A portion of the pressurized water from the centrifugal pump (above ground) is diverted down a pipe to the injector assembly.
- This water is forced through a nozzle, which significantly increases its velocity.
- The high-velocity jet of water then passes into a venturi tube. The venturi effect creates a region of very low pressure just after the nozzle.
- This low-pressure area sucks up additional water from the well, which then mixes with the high-velocity jet.
- The combined water then flows up a return pipe back to the surface, where the centrifugal pump provides the final push into the pressure tank or distribution system.
How They Work Together
The pump and pipe system in a deep well jet pump are always full of water. The centrifugal pump at the surface provides the initial pressure to drive a portion of the water down to the submerged injector. The injector then uses this pressurized flow to create a vacuum that pulls additional water from the well. Both streams of water (the drive water and the well water) are then returned to the surface pump, which delivers the combined volume to its destination.
This ingenious combination allows the deep well jet pump to overcome the atmospheric pressure limits that restrict the suction lift of conventional centrifugal pumps, making it suitable for wells where the water level is too low for a surface pump alone.
