A jet pump in a water well uses a nozzle to create a vacuum, drawing water up from the well.
Here's a breakdown of how it works, incorporating information from the provided reference:
The Core Mechanism
The jet pump operates on the principle of creating a low-pressure area to draw water. Here's how it achieves this:
- Nozzle and Venturi: The core of a jet pump is the jet nozzle and the venturi. Water is pushed through the jet nozzle, which narrows the opening, causing the water's velocity to increase and creating a low-pressure area.
- Vacuum Creation: This high-velocity water stream and the low pressure surrounding the jet nozzle creates a vacuum that draws water from the well. As the reference explains, "Water. Around the jet nozzle is drawn into the water stream."
- Water Entrainment: The incoming well water is pulled into the higher velocity water stream and carried along to the pump's impeller.
Shallow Well vs. Deep Well Jet Pumps
The placement of the ejector, the part containing the nozzle and venturi, differs based on well depth:
| Feature | Shallow Well Jet Pump | Deep Well Jet Pump |
|---|---|---|
| Ejector Location | Mounted within the pump itself, in front of the impeller. | Located down in the well casing, submerged in water. |
| Pumping Method | Relies on suction to draw water up from a relatively short distance. | Uses a combination of vacuum and pushing force to lift water from greater depths. |
As indicated by the reference, "For shallow wells the ejector is mounted in the pump. In front of the impeller."
Jet Pump Function Step-by-Step:
- Initial Water Flow: The pump starts by directing water through the nozzle.
- Vacuum Generation: This water passes through the nozzle, creating the low-pressure vacuum.
- Water Intake: The vacuum draws water from the well into the pump system.
- Mixing and Pumping: The drawn water mixes with the recirculating water and is then pushed through the impeller to increase the pressure.
Key Aspects
- Shallow Well Limitation: Jet pumps for shallow wells have limits as to how deep they can pull water.
- Recirculation: A portion of the water is continually recirculated through the jet to maintain the vacuum and continue to pull water from the well.
Jet pumps are reliable for certain situations, but understanding their operation and limitations is critical for optimal use.
