Experts in centrifugal pumps, come in! !

Most centrifugal pumps use a closed design because it offers higher efficiency. Semi-open and open types are used, as I know, in applications involving the transport of solids, such as slurry pumps. Open or semi-open types are also used in municipal sewage transportation, and in such cases the design of the impeller also undergoes certain changes.

Impeller: The impeller is a key component of a centrifugal pump, as it is from the impeller that the liquid obtains its energy. In other words, the function of the impeller is to transfer the mechanical energy of the prime mover to the liquid, thereby increasing both the static pressure energy and kinetic energy of the fluid passing through the centrifugal pump. The impeller usually consists of 6 to 12 backward-curving blades. Based on their mechanical structure, impellers can be divided into three types: open, semi-closed, and closed. Those with front and rear cover plates on both sides of the blades are known as closed impellers; they are suitable for transporting clean liquids, and this type of impeller is commonly used in centrifugal pumps. An impeller that has no front or rear cover plates, and is composed only of blades and a hub, is called an open impeller. Only those with a rear cover plate are called semi-spherical impellers. Open and semi-closed impellers are suitable for liquid suspensions containing solid particles, as their flow channels are less prone to clogging. However, due to the lack of a cover plate, backflow is likely to occur as the liquid flows between the blades, resulting in lower efficiency for these types of pumps.

Agree with what was said on the 2nd floor. Addition: 1. The axial force of a closed impeller is relatively small ； Semi-open impellers and open impellers experience greater axial forces. 2. Whether to use a semi-open impeller or an open impeller depends on the properties of the medium being transported. That is, the viscosity of the medium, the particle size and content of solid particles, etc.

Closed impellers are used for transporting clear liquids; open and semi-open impellers are employed for transporting liquids with high viscosity or those containing suspended solid particles. These types of impellers are less prone to clogging during transportation, but fluid backflow can occur as it moves between the blades, resulting in low efficiency.

A closed impeller has a sealed flow channel, resulting in low frictional losses due to fluid flow; it is used for high head applications and the transport of clean liquids. Most centrifugal pumps use closed impellers. Open and semi-closed impellers ensure that flow is less prone to blockage, making them suitable for transporting liquids with high viscosity or those containing solid particles. However, the efficiency is low because the outer periphery of the impeller does not fit tightly.

I said the opposite – the closed type has the greatest axial force, the open type the smallest, and the semi-open type falls in between.

Open impellers have no cover plates on either side of the blades; they are simple to manufacture and easy to clean. They are suitable for transporting materials containing a large amount of suspended solids, but their efficiency is low and they cannot handle liquids at high pressures； The semi-closed impeller has no cover on the suction side but one on the other side; it is suitable for transporting materials that tend to settle or contain particles, and its efficiency is relatively low ； A closed impeller has front and rear cover plates on both sides of the blades; it offers high efficiency and is suitable for transporting clean liquids free from impurities. Most centrifugal pump impellers are of this type.

Closed-type pumps are the most common and have the widest range of applications; they can be used with various media and in pumps of different designs, and their bearings can handle significant loads well. It can balance axial forces. Semi-open types are mainly used for sewage, with all axial forces acting on the bearings! Open impellers are commonly used in applications with many particles and are sensitive to the axial clearance. The shafting system needs to have an adjustment function! The above is a brief comparison. Specific applications must change from time to time.

Closed impellers offer high head and high hydraulic efficiency, and are widely used for fluid media free from impurities. Open impellers are generally used for transporting slurries, as well as liquids with high viscosity or those containing suspended solid particles; they are less prone to clogging, but fluid backflow between the blades occurs easily, resulting in lower head and efficiency. Semi-closed lies between the two. Of course, that’s a different story if an inducer wheel is added. On floor 7, it was mentioned that the axial force refers to the force that drives the rotor toward the inlet. Common methods to eliminate this force include creating balance holes, using balance tubes, installing balance blades, or employing a double-suction impeller (which is unnecessary)

I only know that closed systems are suitable for sewage or situations with a high content of solid particles, while open systems are suitable for clean water, that is, in areas with a low content of such particles.

Impellers are classified according to the main flow direction of the fluid relative to the rotational axis. Therefore, centrifugal pumps come in various types: radial impellers, axial impellers, and mixed-flow impellers, which combine the principles of radial and axial flow. Impellers can be further divided into: single-suction impellers, which have an inlet on one side of the impeller; and double-suction impellers, in which fluid flows into the impeller symmetrically from both sides. Based on their mechanical structure, impellers can also be classified as: closed impellers, whose flow channels are enclosed by covers or side walls; open impellers, which lack such covers; and semi-open or semi-closed impellers. The general working medium is a key factor in selecting the impeller.

The impeller is a key component of a centrifugal pump, as it is from the impeller that the liquid obtains its energy; in other words, the function of the impeller is to transfer the mechanical energy of the prime mover to the liquid, thereby increasing both the static pressure energy and kinetic energy of the fluid passing through the centrifugal pump. The impeller usually consists of 6 to 12 backward-curving blades. Based on their mechanical structure, impellers can be divided into three types: open, semi-closed, and closed. Those with front and rear cover plates on both sides of the blades are known as closed impellers; they are suitable for transporting clean liquids, and this type of impeller is commonly used in centrifugal pumps. An impeller that has no front or rear cover plates, and is composed only of blades and a hub, is called an open impeller. Only those with a rear cover plate are called semi-spherical impellers. Open and semi-closed impellers are suitable for liquid suspensions containing solid particles, as their flow channels are less prone to clogging. However, due to the lack of a cover plate, backflow is likely to occur as the liquid flows between the blades, resulting in lower efficiency for these types of pumps. This post was last edited by 156026692 on 2009-4-16 22:43]

Fully closed, semi-closed, open type; efficiency from high to low; material cleanliness from low to high; detailed chemical principles

The open impeller is chosen to prevent blockage of the medium inside the impeller; for media that are easy to deform under operating conditions, the open impeller has the lowest efficiency, and it is a choice made out of necessity. Closed impellers are suitable for particle-free environments and offer the highest efficiency. Semi-open impellers fall between the two.

Thank you all for the introductions; now I realize that many hands make light work! ! Thank you! !

Semi-open types are generally used in situations with high viscosity, such as tar

Salt slurry pumps use open impellers, while alkali liquid transfer pumps use closed impellers.

14th floor: The cleanliness level should go from high to low, right?

The descriptions in books on fluid machinery are very detailed; prison LZ should study them carefully*. Centrifugal pumps are the most common type of pump in the chemical industry.

The functions of various impellers are generally understandable; regarding the issue of axial force, I agree with the view expressed by the user on floor 7.