Common Misunderstandings in the Large-Flow Application of Split Case Pumps

Split case pumps have become the main conveying equipment in fields such as municipal water supply, industrial circulation, and farmland irrigation due to their core advantages of large flow, stable operation, and convenient maintenance. However, in the actual application of large-flow working conditions, many users fall into many misunderstandings in key links such as selection, installation, and operation due to insufficient understanding of equipment characteristics and working condition matching principles, which directly leads to soaring energy consumption, frequent equipment failures, and shortened service life.

1: Blindly Pursuing "Larger is Better" in Selection, Ignoring Working Condition Adaptability

For example, the head of the equipment selected for the circulating system of a power plant is too high, and the actual operating head is only 37.5% of the design value, which directly causes severe cavitation and impeller perforation damage within two months. The correct selection should follow the principle of "peak flow matching + reasonable margin". For large-flow and low-head equipment, the flow margin can be 5%. At the same time, parameters should be determined in combination with core factors such as the characteristics of the conveying medium and the conveying distance to avoid the waste phenomenon of "using a large horse to pull a small cart".

 2: Random Pipeline Configuration, Ignoring Resistance and Air Intake Problems

Too small pipe diameter will sharply increase the resistance of the conveying pipeline, leading to increased head loss; upward tilting or horizontal installation of the suction pipe is likely to accumulate air, causing the "air binding" phenomenon and greatly reducing the water output; horizontal elbows will damage the stability of water flow and increase operating energy consumption. The standard configuration method is to select a pipe diameter matching the pump port, incline the suction pipe towards the water source, give priority to vertical turns for elbows, and avoid direct connection between the water inlet and the elbow.

 3: Improper Flow Regulation Method, Over-Reliance on Valve Throttling

Some users control the flow by closing the outlet valve for a long time during operation. Although it can temporarily adjust the operating parameters, it will lead to a sharp increase in pipeline resistance and abnormal load of the supporting motor, which not only increases the operating energy consumption but also may cause valve damage. For large-flow regulation, frequency converter speed regulation or speed adjustment should be preferred. If a long-term fixed flow is required, it can be achieved by replacing the small-diameter impeller. This regulation method is not only energy-saving but also ensures stable equipment operation.

4: Confusing Applicable Scenarios with Mixed Flow Pumps, Wrong Selection of Substitutes

Both split case pumps and mixed flow pumps are suitable for large-flow scenarios, but many users ignore the differences in head and conveying distance and blindly replace the latter with the former. From the perspective of equipment characteristics, mixed flow pumps are more suitable for low-head and short-distance conveying. When the conveying head exceeds 10 meters, split case pumps should be selected. Forcing use in short-distance and low-head scenarios will not only result in higher cost but also reduce operating efficiency due to mismatched working conditions, causing double waste of investment and energy consumption.

 5: Negligence in Startup and Maintenance, Ignoring Air Binding and Lubrication Protection

Failure to drain the air in the pump body before startup and insufficient submergence depth of the suction pipe are common startup misunderstandings in large-flow applications, which are likely to lead to failure to suck water or sudden drop in flow. At the same time, some users ignore seal cooling and lubrication maintenance. For example, insufficient cooling water flow of the mechanical seal and excessive or insufficient filling of bearing grease will cause failures such as wear of the seal surface and overheating of the bearing. The correct operation should ensure that the air in the pump body is drained before startup, the submergence depth of the suction pipe is not less than 0.8 meters, the cooling system and lubrication status are regularly checked, and grease is supplemented according to specifications.