The axial split case pumps are widely used in water treatment, chemical industry, agricultural irrigation and other fields. Their main function is to transport liquid from one place to another. However, when the pump absorbs water, its suction range is usually limited to five to six meters, which has raised questions among many users. This article will explore the reasons for the limitation of pump suction range and the physical principles behind it.

Before discussing, we must first make it clear that the suction range of the pump is not the head. The difference between the two is as follows:

1.Suction Range

Definition: The suction range refers to the height at which the pump can absorb liquid, that is, the vertical distance from the liquid surface to the inlet of the pump. It usually refers to the maximum height at which the pump can effectively absorb water under negative pressure conditions.

Influencing factors: The suction range is affected by factors such as atmospheric pressure, gas compression in the pump, and the vapor pressure of the liquid. Under normal circumstances, the effective suction range of the pump is usually around 5 to 6 meters.

2.Head

Definition: The head refers to the height that theaxial split case pumpcan generate through the liquid, that is, the height at which the pump can lift the liquid from the inlet to the outlet. The head not only includes the lifting height of the pump, but also other factors such as pipeline friction loss and local resistance loss.

Influencing factors: The head is affected by the performance curve of the pump, flow rate, density and viscosity of the liquid, length and diameter of the pipeline, etc. The head reflects the working capacity of the pump under specific working conditions.

The basic principle of the axial split case pump is to use the centrifugal force generated by the rotating impeller to drive the liquid flow. When the impeller rotates, the liquid is sucked into the inlet of the pump, and then the liquid is accelerated and pushed out of the outlet of the pump by the rotation of the impeller. The suction of the pump is achieved by relying on atmospheric pressure and the relatively low pressure difference in the pump. The difference in atmospheric pressure will also affect:

Limitation of Atmospheric Pressure

The suction range of the pump is directly affected by atmospheric pressure. At sea level, the standard atmospheric pressure is about 101.3 kPa (760 mmHg), which means that under ideal conditions, the suction range of the pump can theoretically reach about 10.3 meters. However, due to friction loss in the liquid, gravity and other factors, the actual suction range is generally limited to 5 to 6 meters.

Gas Compression and Vacuum

As the suction range increases, the pressure generated inside the pump decreases. When the height of the inhaled liquid exceeds the effective suction range of the pump, a vacuum may form inside the pump. This situation will cause the gas in the pump to compress, affecting the flow of the liquid and even causing the pump to malfunction.

Liquid Vapor Pressure

Each liquid has its own specific vapor pressure. When the vapor pressure of a liquid is close to atmospheric pressure, it tends to evaporate and form bubbles. In the structure of a axial split case pump, the formation of bubbles can lead to fluid dynamic instability, and in severe cases, it can also cause cavitation, which not only reduces the performance of the pump, but may also damage the pump casing.

Structural Design Limitations

The design of the pump is based on specific fluid mechanics principles, and the design and material of its impeller and pump casing are closely related to its working characteristics. Due to the natural characteristics of the axial split case pump, the design does not support a higher suction range, which greatly reduces its working efficiency at a suction range of more than five or six meters.

Conclusion

The suction range limit of the axial split case pump is determined by multiple factors such as atmospheric pressure, liquid characteristics and pump design. Understanding the reason for this limitation will help users make reasonable choices when applying pumps and avoid equipment efficiency and failure problems caused by excessive suction. For equipment that requires a larger suction, consider using a self-priming pump or other types of pumps to meet specific usage requirements. Only through correct equipment selection and use can the performance of the pump be fully utilized.