Factors That Limit Suction Lift in Jet Pumps?

Factors Affecting Suction Lift

The primary factor limiting suction lift in jet pumps is atmospheric pressure, which is approximately 14.7 psi at sea level. As water column height increases, the pressure at the bottom of the well decreases, making it more difficult for the pump to create suction. For every 10 feet of water column height, the pressure decreases by about 0.433 psi.

Calculating Maximum Suction Lift

To calculate the maximum suction lift for a given well, you can use the following formula: suction lift (ft) = 2.31 x (pressure at top of well - atmospheric pressure) / (specific gravity of water x acceleration due to gravity). For example, if the pressure at the top of the well is 10 psi, the maximum suction lift would be approximately 21.7 feet. However, this calculation assumes a short, straight hose and ideal conditions. In practice, suction lift may be limited by other factors, such as hose length and diameter, and the presence of any restrictions or kinks in the hose.

Practical Considerations

When designing a shallow well system with a jet pump, it’s essential to consider the available suction lift. A general rule of thumb is to limit the suction lift to no more than 20-25 feet for a standard jet pump. To achieve greater suction lift, you may need to use a more powerful pump or install a submersible pump. It’s also crucial to ensure that the hose is properly sized and supported to minimize restrictions and kinks.