The device and principle of operation of centrifugal pumps. Classification, characteristics

If we consider the devices that are used for pumping liquids, the most practical will be a centrifugal pump. This equipment has high performance and provides a powerful head, but the design with all the positive features is extremely simple. Pumping stations and household pumps, which are used for organizing an autonomous water supply system or for irrigation of suburban areas, are of this type.

Pump unit

The device and principle of operation of centrifugal pumps will be described in the article. If we consider the first part of the question, then we can distinguish that the working element in a simple design consists of a body that looks like a cochlea or spiral. Inside is the shaft and impeller, the last of which is fixed just on the shaft. The key provides the transfer of rotation from shaft to wheel. The impeller has two discs and blades, which are fixed between them.

The blades are curved and facing the direction of rotation with the bulging side. If you are interested in the characteristics of centrifugal pumps, then you should be aware that the body is made of cast iron or steel, but impellers are usually made of polymers. The impeller shaft in different models can be cantilever or two-bearing. In the latter case, the design is supplemented by bearings. Going out of the body and connecting with the rotor of the crankshaft or electric shaft with a clutch, the shank acts as a drive.

In order to prevent leakage of the pumped substance through the openings in the housing, the construction is provided with a seal.

Reliable tightness

If you are interested in the device and the principle of operation of centrifugal pumps, it is best to give preference to the equipment that has an end seal of the shaft at the time of purchase. This version is more reliable than the stuffing box, which is now considered obsolete. The mechanical seal ensures complete leakproofness of the housing even when the impeller shaft is displaced. High reliability is guaranteed even with vibrations that can not be avoided while the pump is running.

Operating principle

After the device and principle of operation of centrifugal pumps become known to you, you can purchase the equipment and start installing it. However, before this, it is worthwhile to become more familiar with the principle of operation of the described unit. Thus, after the engine has been started, the pump shaft starts to rotate. Blades of the wheel drive the substance in the working chamber. The liquid begins to move around in a circle, undergoing a centrifugal force. The module of this force will be greater, the further the molecules of the pumped medium will be from the center of rotation. In the end, the water will be thrown to the periphery of the impeller, then it will go to the outlet pipe. This ensures the maintenance of pressure due to centrifugal force.

Classification by number of steps

In order to make the right choice of equipment, it is necessary to know the device and principle of operation of centrifugal pumps. This also applies to classification. Separate aggregates can be a number of features, including the number of steps. The units can be single-stage or multi-stage. In the first case, only one impeller is installed in the structure, this system is classical. If there is a need to develop a significant head, then multi-stage pumps are used, in which there are several impellers installed on one shaft. The principle of operation of such equipment is that each wheel with a working chamber forms a stage. The housing is designed in such a way that the liquid passes from one stage to the other until it reaches the outlet pipe.

Classification in the direction of the axis of rotation

If you are interested in the characteristics of centrifugal pumps, then you must first determine which class belongs to this or that equipment. The devices can also be subdivided in the direction of the axis of rotation. This indicates that the shaft can be in a horizontal or vertical position.

The first option is considered the most common, which is due to ease of maintenance. The second version assumes less space for installation, since the engine is under the hull. This type can be attributed to most of the downhole pumps, which are designed to work in crowded conditions. Such a centrifugal pump for a well has one minus, which is expressed in the fact that the maintenance or repair of the housing will have to remove the engine.

Classification of pumps by installation method and their characteristics

For sale are centrifugal industrial pumps in a wide range, they can differ among themselves in the manner of installation. Depending on the purposes and conditions of use set before the equipment, a surface, semi-submersible or submersible pump should be chosen. Surface ones are located directly near the source or at some distance from it. Pay for such equipment will be less. The device will be permanently in view, indicating that it is easily accessible for maintenance and monitoring. The disadvantage is the condition that the water level in the source must be 8 meters or higher relative to the installation level of the unit. That is why such equipment will not work with deep wells and wells.

Characteristics of submersible and submersible pumps

Considering industrial pumps, you will probably pay attention to semi-submersible models in which the shaft is located vertically. Some part of the hull will be submerged in the source, most often this equipment is used to pump fluid out of the pits. When there is a need to pump out liquid from deep wells and wells, submersible pumps are used, which are suspended during the operation by a chain or cable.

The device must be completely immersed in water. Since the operation of a submersible centrifugal pump will be accompanied by the action of an aggressive medium on the housing, it must have certain characteristics, among which are the corrosion resistance of the external components of the structure, the tightness of the housing and the electrical part, and the elimination of the likelihood of engine oil leaks through the pump structure. The latter requirement is very important, because if you get into the well or a borehole of engine oil, removing it will be very problematic and expensive.

Classification of pumps by the method of water intake and equipment characteristics

The performance of a centrifugal pump will depend on the engine power, this characteristic can be found in the device's passport. You should not save by purchasing the unit with a minimum power, since in this case, under heavy loads, the equipment will run on wear. However, this parameter is one of the most important when choosing. It is required to draw before buying and also on what method of water intake is used by this or that model. Scheme of the centrifugal pump will allow you to understand what parts of the structure consists of, this is especially important if you will perform the installation work yourself. It is necessary to understand also with what equipment is before you: a normal suction pump or a self-priming device.

In the first case, water can flow by gravity, while self-priming models will be able to raise water from a certain depth. As practice shows, this parameter does not exceed 8 meters.