The slurry pump is suitable for conveying liquid (medium) containing suspended solids, including many kinds: slurry pumps, impurity pumps, dredging pumps etc. At present, they are one of the indispensable equipment in the process of mineral processing, coal preparation, desulfurization, filter press feeding and so on. For this reason, the sealing of slurry pump is also constantly valued. Choosing the right sealing method can not only greatly improve the service life of the pump in the field, but also reduce economic losses.
There are 3 type shaft seals of slurry pump: packing seal, expeller seal and mechanical seal.
Packing seal is the most common kind of seal. The filler added in the packing box contacts fully with the shaft and injects a certain pressure water into the filler to prevent the leakage of the conveying medium, so as to achieve the sealing purpose. The pressure of shaft seal water must exceed the outlet pressure of slurry pump by 1.5 kg. When conveying corrosive materials, the packing may be corroded, so the disadvantage of this sealing form is that it can not convey toxic and corrosive liquids. The packing shaft seal has simple structure, convenient maintenance and low price. It is widely used in concentrator and coal washery.
The expeller seal relies on the reverse centrifugal force produced by the auxiliary impeller to prevent the slurry from leaking out. The use of expeller seal requires that the reverse grouting pressure of the slurry pump should not exceed 15% of the slurry pump outlet pressure. The first stage pump of the single-stage pump or multi-stage series pump can adopt the auxiliary impeller shaft seal. The shaft seal of the expeller seal has no need for shaft seal water and does not dilute the slurry, and the sealing effect is good. Therefore, this seal can be considered when dilution is not allowed in slurry or when there is no flushing water in the user's operation site.
Mechanical seal is the dynamic ring and static ring close contact along the axis of the spring to achieve the purpose of sealing. Mechanical seals are reliable and almost leak-free, but when installing, attention should be paid to protecting the friction surface to avoid wear and tear. Mechanical seals are generally divided into single-end mechanical seals and double-end mechanical seals.
Choosing a reliable slurry pump to operate in the field, not only the appropriate material for the flow passage parts, but also the appropriate sealing mode for the shaft seals. According to the characteristics of the conveying medium on site, the suitable slurry pump seal is selected under the working conditions, which can not only ensure the reliable operation of the pump for a long time, but also reduce the economic investment loss.
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