What type of packing is commonly used in centrifugal pumps?

Centrifugal pumps typically utilize soft metallic packing due to its effectiveness in creating a reliable seal around the rotating shaft while allowing for some degree of flexibility. This type of packing can withstand the varying levels of pressure and temperatures common in pump applications. Soft metallic packing, often made from materials like braided metal fibers or other soft metals, provides durability and can be adjusted during operation to minimize leakage, which is crucial for maintaining efficiency in centrifugal pump systems.

In addition, soft metallic packing is less prone to degradation compared to other materials, making it a preferred choice in environments that involve exposure to corrosive substances or high temperatures. The materials used in soft metallic packing also have good thermal conductivity, which can help dissipate heat generated within the pump, further enhancing performance and longevity.

While rubber sealing may offer good flexibility and resistance to wear, it typically does not provide the same level of heat resistance or longevity in high-pressure applications as soft metallic packing. Plastic wrapping and cementitious materials are not common in centrifugal pump applications because they do not possess the necessary resilience and sealing capabilities required for effective pump operation.