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Classification and determination of shaft seals

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The shaft seal is a sealing device that prevents the pump shaft and the casing from leaking. The commonly used shaft seal type has packing seal, mechanical seal and dynamic seal.
The shaft seal of the reciprocating pump is usually a packing seal. When transporting the medium that is not allowed to leak, the diaphragm type reciprocating pump can be used. The shaft seal of the rotary pump (including vane pump, rotor pump, etc.) mainly has packing seal, mechanical seal and Power sealing.
1. Packing seal packing seal layout is simple, cheap, easy to repair; but large leakage, power loss is large. Therefore, packing seals are used to transport ordinary media; such as water, usually not suitable for petroleum and chemical media; especially not valuable, Blasting dangerous or toxic medium.
2. The mechanical seal mechanical seal (also known as the end seal) has a good sealing effect; the amount of leakage is very high. The 倜ぃ 鄹窠瞎螅 ぐ沧 ぐ沧 ぐ沧 ぐ沧 Q Q Q Q 机械 机械 机械 机械 机械 机械 机械 机械 机械 机械 机械. Mechanical seals are suitable for transporting petroleum and chemical media; Can be used for a variety of different viscosity, strong corrosive and particle-containing media. American Petroleum Institute standard APl610 rules: in addition to the user has rules; should be equipped with a cartridge mechanical seal.
3. The dynamic seal dynamic seal can be divided into two types: the back blade seal and the auxiliary impeller seal. The centrifugal force effect of the back blade (or the auxiliary impeller) during pump operation reduces the medium pressure at the shaft seal to the normal pressure or negative pressure condition; No leakage during the process. The centrifugal force is not visible when parking; the sealing effect of the back blade (or auxiliary impeller) is invalid; at this time, the parking sealing device acts as a sealing effect. In the parking sealing device matched with the back blade (or auxiliary impeller) Filler seals are used more. Packing seals are available in both general and mechanical elastic. Common packing seals are similar to conventional packing seal pumps; the required shaft seals adhere to micro-positive pressure; to prevent dry conflict of fillers. Mechanically elastic The packing parking seal is selected from the counterweight; the packing is loosened during operation; the packing is compacted during parking.
To ensure the life of the parking seal equipment; reduce the leakage of the pump; for the pump with the power seal; the pump inlet pressure should be constrained;
PS<10%pd
Ps pump inlet pressure; MPa,
Pd pump outlet pressure; MPa.
Power sealing function is reliable; cheap price; convenient for repair; suitable for transporting medium rich in solid particles; such as slurry pump, slurry pump, chemical pump, corrosion resistant pump, stainless steel pipeline pump in phosphoric acid industry, etc. Loss is larger than mechanical seals; and its parking seals have a shorter life.

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