Factors to be considered in pump selection:
(1) Corrosiveness of the medium. The material has a certain range of corrosion resistance to the medium. For example, acid steel 1Cr18Ni9, medium and dilute concentrations of nitric acid or organic acids, but not sulfuric acid.
(2) Electrochemical corrosion. It is best to use the same metal material throughout the entire flow path of the pump.
(3) Medium temperature. The material is brittle at very low temperatures, and creep will occur at high temperatures; a material can withstand the corrosion of a medium at normal temperature, but it is not resistant to the corrosion of the medium at high temperatures; the material properties should be able to meet the temperature of the medium being transported Claim.
(4) Economy. It is not economical to use high-grade materials or low-grade materials or corrosion-resistant materials in the design or use of non-corrosive materials.
(5) Abrasion resistance of solid particles. When the medium contains abrasive solid particles, wear-resistant materials should be used.
(6) occlusion between materials. For parts with relative movement, such as shafts and shaft sleeves, bolts and nuts, impeller seal rings and pump body seal rings, balance discs and balance plates, etc., the material hardness of the two parts should be slightly different when choosing materials, otherwise they will be handled during loading Or it is easy to bite or scratch each other during operation.
(7) The magnitude of the temperature difference on the same part. Parts with very different temperatures at the same location during work, such as where the cooling water jacket of the stuffing box of the hot oil pump is connected to the pump body, the temperature of the pump body in contact with the medium is high and the expansion is large; Low and little swelling. Such parts should be made of plastic materials to avoid cracks due to different expansion during operation.
(8) Where high-speed liquid flow passes. Impeller blades of high-lift pumps, inlet edges of guide vane blades, single-stage high-seal sealing sleeves, high-lift pump balance sleeves, balance discs, and balance plates should be made of erosion-resistant materials (chrome stainless steel or chromium-nickel acid-resistant steel) .
(9) Parts requiring welding. Parts that need to be repaired during casting, processing and use should be made of materials with good weldability (for example, low carbon steel has better weldability than high carbon steel).
(10) The single-stage lift is very high. For pumps with single-stage lifts of hundreds of meters or even kilometers, the material of the impeller and guide vanes should be high-strength steel that is resistant to erosion and cavitation, such as precipitation-hardened stainless steel.
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