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The role of the main parts of the D-type multistage pump

16 May 2021Email

Before replacing parts or repairing the D-type multi-stage pump, it is necessary to understand which parts the D-type multi-stage pump is composed of in order to facilitate the maintenance and replacement of related parts. The D-type multi-stage pump parts mainly consist of centrifugal pump casing, impeller, sealing ring, impeller nut, pump cover, mechanical seal part, matching motor and other parts.

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The role of the main components of the D-type multistage pump:

1. The role of the D-type multistage pump casing. The function is to close the impeller in a certain space so that the liquid can be sucked in and pressed out by the action of the impeller. The pump casing is mostly made into a volute shape, so it is also called a volute. As the cross-sectional area of ​​the flow channel gradually expands, the high-speed liquid thrown around the impeller gradually reduces the flow rate, so that part of the kinetic energy is effectively converted into static pressure energy. The pump casing not only collects the liquid thrown out by the impeller, but also an energy conversion device.

The shell shape of most horizontal multi-stage centrifugal pumps is basically a volute type, and the radially split shell of multi-stage horizontal centrifugal pumps is usually a circular shell or an annular shell. Commonly used volute-type pump casing has a spiral liquid channel in the inner cavity to collect the liquid thrown from the impeller and make it diffuse to the outlet of the centrifugal pump. The pump casing of the centrifugal pump bears all the working pressure and the heat load of the medium.

2. The role of D-type multi-stage pump impeller. The centrifugal pump impeller is the only moving part. The multi-stage pump exerts force on the medium through the impeller. The impeller has three forms: closed impeller, open impeller, and semi-open impeller. The efficiency of the closed impeller is higher, and the efficiency of the open impeller is lower. The commonly used multi-stage centrifugal pump products are all closed impellers, so the D type is more efficient.

The function of the impeller is to directly transfer the mechanical energy of the prime mover to the liquid to increase the static pressure energy and kinetic energy of the liquid (mainly increase the static pressure energy).

The impeller generally has 6 to 12 backward curved blades.

There are three types of impellers: open, semi-closed and closed.

The open impeller has no cover on both sides of the blade, which is simple to manufacture and easy to clean. It is suitable for conveying materials with a large amount of suspended matter. The efficiency is low and the conveying liquid pressure is not high; the semi-closed impeller has no cover on the suction side Plate, and there is a cover plate on the other side, which is suitable for conveying materials that are easy to deposit or contain particles, and the efficiency is also low; the closed impeller has front and rear cover plates on both sides of the impeller, which is high in efficiency and suitable for conveying without impurities Of cleaning liquid. General centrifugal pump impellers are mostly of this type.

The impeller has two suction methods, single suction and double suction.

3. Sealing ring of D-type multi-stage pump. The seal ring of centrifugal pump is also commonly referred to as O-ring. The role of O-ring is to prevent internal and external leakage of the pump. O-rings made of nitrile rubber or fluorine rubber and PTFE are installed on the impeller. The cover plate and pump casing can be easily replaced when damaged.

4. D-type multi-stage pump shaft and bearings. The centrifugal pump shaft has a fixed impeller at one end and a motor rotor or a pump with a coupling at the other end with a coupling. According to the size of the centrifugal pump, different types of bearings can be selected to include rolling bearings and sliding bearings.

5. D-type multi-stage pump seal. The function is to prevent the liquid in the pump casing from leaking along the shaft or the outside air from leaking into the pump casing. Centrifugal pump seals generally have two types: mechanical seals or packing seals. The filler is generally oil-impregnated or coated with graphite asbestos rope. The mechanical seal mainly relies on the relative movement between the moving ring mounted on the shaft and the static ring fixed on the pump casing to achieve the purpose of sealing.

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