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 domestic pumps, which are used to organize an autonomous water supply system or for watering summer cottages, are of this type.
Pump device
The device and principle of operation of centrifugal pumps will be described in the article. If we consider the first part of the question, we can distinguish that the working element in a simple design consists of a body that looks like a snail or spiral. Inside there is a shaft and an impeller, the last of which is fixed just on the shaft. The key provides transmission of rotation from the shaft to the wheel. The impeller has two discs and vanes, which are fixed between them.
The blades have a curved shape and face protruding to the direction of rotation. If you are interested in the characteristics of centrifugal pumps, then you should know that the casing is made of cast iron or steel, but the impellers are usually made of polymers. The impeller shaft in different models can be cantilever or double-bearing. In the latter case, the design is supplemented by bearings. Going beyond the housing and communicating with the rotor of the crankshaft or electric shaft using a coupling, the shank acts as a drive.
In order to prevent leakage of the pumped substance through the holes in the housing, the design is endowed 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 equipment that has a mechanical shaft seal at the time of purchase. This option is more reliable than the stuffing box packing, which is currently considered obsolete. The mechanical seal ensures complete tightness of the housing even when the impeller shaft is biased. High reliability is guaranteed even with vibrations that cannot be avoided during the operation of the pump.
Operating principle
After the device and the principle of operation of centrifugal pumps become known to you, you can purchase equipment and proceed with its installation. However, before this, it is worthwhile to become more familiar with what principle of operation the described unit uses. Thus, after the engine is started, the pump shaft begins to rotate. The blades of the wheel drive the substance in the working chamber. The fluid begins to move in a circle, undergoing centrifugal force. The modulus of this force will be greater, the farther the molecules of the pumped medium will be from the center of rotation. Ultimately, the water will be ejected to the periphery of the impeller, after which it will enter the outlet pipe. This ensures that pressure is maintained by centrifugal force.
Classification by the number of steps
In order to make the right choice of equipment, it is necessary to know the device and the principle of operation of centrifugal pumps. This also applies to classification. Aggregates can be divided according to a number of signs, including the number of steps. Installations can be single-stage and multi-stage. In the first case, only one impeller is installed in the design, this system is a classic. If there is a need to develop significant pressure, then multistage pumps are used, in which several impellers are installed on one shaft. The principle of operation of such equipment is that each wheel with a working chamber forms a step. The housing is designed in such a way that the liquid passes from one stage to another 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 what class this or that equipment belongs to. You can also subdivide devices in the direction of the axis of rotation. This indicates that the shaft may be in horizontal or vertical position.
The first option is considered the most common, due to ease of maintenance. The second variant involves less installation space, as the engine is under the body. This type includes the majority of borehole pumps, which are designed to operate in cramped conditions. Such a centrifugal pump for a well has one drawback, which is expressed in the fact that it will be necessary to remove the engine to service or repair the body.
Classification of pumps by installation method and their characteristics
A wide range of centrifugal industrial pumps are on sale; they may differ from each other in the way they are installed. Depending on the goals set for the equipment and the conditions of use, you should choose a surface, semi-submersible or submersible pump. Surface are located directly near the source or at some distance from it. Pay for such equipment will have less. The device will be constantly in sight, indicating easy access for maintenance and monitoring. The disadvantage is the condition under which the water level in the source should 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
When considering industrial pumps, you will surely pay attention to semi-submersible models in which the shaft is located vertically. Some part of the body will be immersed in the source, most often such equipment is used to pump liquid from the sumps. When there is a need to pump liquid from deep wells and wells, submersible pumps are used, which are suspended on a chain or cable during operation.
The device will be completely immersed in water. Since the operation of a submersible centrifugal pump will be accompanied by the action of an aggressive environment on the casing, it must have certain characteristics, among which are corrosion resistance of the external structural elements, the tightness of the casing and the electrical part, as well as the elimination of the possibility of leakage of machine oil through the pump design. The last requirement is very important, since if engine oil enters a well or a well, removing it will be very problematic and expensive.
Classification of pumps by the method of water intake and equipment characteristics
The performance of the centrifugal pump will depend on the engine power, you can find this characteristic in the passport of the device. You should not save when purchasing a unit with minimal power, since in this case, under heavy loads, the equipment will work for wear. However, this option is one of the most important when choosing. Before purchasing, it is also necessary to look at which method of water intake is used by one or another model. The centrifugal pump diagram will allow you to understand what parts the structure consists of, this is especially important if you will perform installation work yourself. It is also necessary to understand what equipment is in front of 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 lift water from a certain depth. As practice shows, this parameter does not exceed 8 meters.