The Function and Lubrication of Bearings in Centrifugal Pumps
Due to their design, centrifugal pumps are subjected to radial and axial loads throughout their operation. These loads create continuous stress on the components that make up the pump and cause damage to the materials. At this point, bearings are used both to balance these loads occurring in the pump and to support the rotating equipment. Bearings are therefore one of the most important components making up the pump, and incorrect bearing maintenance or incorrect lubrication shortens pump life.
In all rotating equipment where bearings are used, friction will eventually win out, the bearing will be damaged, and it will need to be replaced. However, by reducing friction to a minimum with correct maintenance and lubrication, it is possible to extend the life of both the bearing and the pump.
Points to Consider When Checking and Lubricating Bearings
- First of all, we need to know the type of lubrication used for the bearing in your pump. Bearings used in pumps are generally grease-lubricated sealed type (single-use), grease-lubricated open type (with replaceable grease), or externally lubricated.
- If the bearing is externally lubricated, non-detergent oils (oils that keep particles within the oil adhered to stationary surfaces of the material, so that no sediment or particles are carried to the points of friction and contact) and non-foaming type oils should be used.
- The types of oil that can be used in the pump, as published by the pump manufacturer, must always be checked, and if the environment and operating conditions of the pump differ significantly from the standard, support must always be requested from the manufacturer on this matter.
- Over-lubrication must always be avoided. Over-lubrication will increase the power drawn by the pump, leading to unnecessary energy consumption, and will generate extra heat in the bearing.
- If excessive cloudiness or sediment is observed when the oil is checked, the oil must be changed as soon as possible.
- If the bearing uses replaceable grease lubrication, a single type and brand of grease should be used in the bearing, and greases of different brands and types should not be mixed.
- Likewise, in grease-lubricated bearings, excessive grease use will cause an increase in temperature and power consumption, and will lead to heat-related damage in the bearing.
- Whether with external oil lubrication or grease lubrication, when changing the lubricant, the sediment and dirt remaining from the previous lubricant must be thoroughly cleaned, and the lubricant change should be carried out after this cleaning.
- If a sealed-type bearing is used in the pump, the bearing must be replaced with a new one as soon as the first signs that a bearing change is needed appear; the seals of the old bearing must not be opened to re-lubricate it and reuse it.
