There are many factors that affect the life of the pump, each of which should be paid attention to. Today, Saiken Pump will talk to you about these common factors, and hope you can pay attention to them when using the pump.

 

1. Radial force

Industry statistics show that the biggest reason for centrifugal pumps to stop running is the failure of bearings and/or mechanical seals. Not only centrifugal pump, the life of positive displacement pump is also affected by radial force. The large radial force and the consequent shaft deflection are the killers of mechanical seals and important factors to shorten the life of bearings. If it is large enough, the radial force will cause the shaft to deflect or bend. If the pump is stopped and the runout on the shaft is measured, no error will occur because it is a dynamic condition, not a static condition.

 

2. Contamination of lubricating oil

For ball bearings, more than 85% of bearing failures are caused by dirt, foreign matter or water. Proper use of clean lubricating oil is critical to life.

 

3. Suction pressure

Other key factors affecting bearing life are suction pressure, coupling alignment, and pipe stress. When selecting the pump, the suction pressure is one of the important reference parameters. If the suction pressure is too high or there is a vacuum, it should be considered whether it is within the self-priming range of the pump, and also consider the pressure bearing of the pump inlet mechanical seal.

 

4. Calibration

The misalignment of pump and motor will overload the radial bearing. When the calculation is misaligned, the radial bearing life is an exponential factor. For example, for small deviations of only 1.52mm, the end user may encounter some bearing or coupling problems after three to five months of operation. However, for the deviation of 0.0254mm, the same pump may operate for more than 90 months.

 

5. Pipe stress

Pipe stress is caused by misalignment between suction pipe or discharge pipe and pump flange. For example, some customers will report that the inlet and outlet flanges have cracks in use, but the pump is tested qualified when it leaves the factory, so it is not ruled out that there is pipeline stress during pipeline installation. Even in a robust pump design, the resulting pipe stresses can easily transfer these potentially high forces to the bearings and their respective shells. The force (strain) causes the bearing to fit improperly and/or be inconsistent with other bearings, so that the centerline is in a different plane.

 

6. Fluid properties

Fluid properties such as pH, viscosity, and specific gravity are key factors. If the medium is acidic or corrosive, the contact parts of the pump, such as the casing and impeller materials, need to maintain a functional state. The quantity, size, shape and grinding quality of solids in the fluid will be the influencing factors.

 

7. Working status

The severity of the working state is another major factor: how often does the pump start in a given time? Some pumps start and stop every few seconds. Compared with pumps that operate continuously under the same conditions, these pumps in operation wear at exponential speed. In this case, the system design needs to be changed urgently.

 

8. NPSH

The higher the margin of available NPSHA, the less likely the pump will cavitate if it exceeds the required NPSHR. Cavitation will damage the pump impeller and the resulting vibration will affect the seals and bearings.

 

9. Pump speed

The running speed of the pump is another key factor. For example, for the same three screw pump, the 2900 rpm pump will wear faster than the 960 rpm pump.

 

10. Rotor balance

Whether it is centrifugal pump or positive displacement pump (gear pump, rotor pump), the balance state of the core rotor is very important, and the loss of balance will directly affect the life of the pump.

 

11. Piping Design

The selection of pump shall be based on the design of the pipeline. The inlet of the pipeline must meet the self-priming capacity of the pump, and the resistance of the outlet of the pipeline must meet the design pressure of the pump, otherwise the self-priming and discharge will be affected.

 

12. Operating and ambient temperature

Before selecting the pump, you must fully understand the working conditions, such as working temperature and ambient temperature, which will directly affect the material selection of the pump and its accessories. In particular, the rate of temperature change will have a significant impact on the life and reliability of the pump. The operating temperature of the pump is important, so the pump needs to be designed to operate at this temperature.