Cantilever Single Stage Centrifugal Pump Designed for pumping stations. In water installations, general-purpose equipment is most often used. For the most part, double-sided pumps of type D are installed at the stations, and if large volumes are needed, console devices are used.
Vertical pumps
The vertical single-stage centrifugal pump is used at buried stations, the construction of which is difficult in conditions of too close a water level. This makes it possible to reduce the cost of construction, reduce the size of the machine room, and improve the quality of operating conditions for electric motors that can be brought to the ground floor.
Axial pumps
Such installations are most often used with large water supplies. Dynamic wastewater pumps are mostly installed at stations of household waste disposal systems. There is a water temperature of up to 80 degrees and a possible content of up to one percent of abrasive particles. In drainage systems, installations of types Gr and GrU can also be used.
Centrifugal single-stage pump and its properties
The operational properties of such pumps are determined by their main parameters: power, pressure, cavitation reserve, supply, suction height. Important qualities of the operation of the units are the voltage of the electric motor and the frequency of rotation of the wheel.
You need to understand that the parameters of axial and centrifugal pumps are variable even with continuous operation of the impeller and will depend on the flow. In the drawings, it is customary to give characteristics for reduced wheel diameters. The characteristics of the optimal operating points correspond to the maximum efficiency. Appropriate set and delivery are acceptable indicators of the pump. These characteristics are entered in the designation of installations.
Working point
The operating point is the position corresponding to the current mode of action. It does not always coincide with an acceptable indicator, but it must be close to them. A single-stage centrifugal pump for water always operates within the working part, which is determined in accordance with the allowable reduction in efficiency. Operating points should only be within these limits. The characteristics of each device are described by the manufacturer with the expectation of clean water with a temperature of twenty degrees at optimal atmospheric pressure at sea level.
Pumps of types K and KM
The horizontal centrifugal single-stage pump operates with a single-sided impeller located on the edge of the pump shaft. Pressure nozzles rotate 90, 180, 270 degrees. It depends on the specific layout conditions. The bearings in the mechanisms are lubricated with a liquid substance. The cantilever single-stage centrifugal pump can have several modifications: installation without an engine (K) and in a monoblock design (KM). After these letters, the flow and pressure are indicated on the marking.
Two-way installations
Class D single stage horizontal pumps with semi-spiral supply are available on the market. The horizontal rise of the cast-iron housing is carried out in the plane of the axis of the shaft. This feature makes it possible to disassemble and repair the device without having to dismantle the pipeline. Each double-sided pump is marked with the symbol "D". After this letter two numbers are indicated: feed and pressure.
What does a console installation consist of?
A single-stage centrifugal pump for water consists of the following parts: spiral housing withdrawal, support, front cover, impeller, suction pipe, nut, shaft, stuffing box sleeve, ball bearing.
The principle of connecting components
By means of unloading openings the axial pressure is partially balanced. The wheel is also equipped with an axial seal on the back. A tube with a pipe is connected to the pump pressure relief chamber . The second ball bearing is mounted to fix the rotor and better perception of unbalanced axial force. A hydraulic seal is provided on the pump glands.
Such plants have a capacity of 28 to 100 liters per second with a pressure of 12 to 98 meters. High-performance single-stage pumps for the most part have the possibility of two-way supply. Under normal axial pressure, a good two-line wheel has a fairly high cavitation performance.
Housing and oil seals
In pumps designed for pumping clean liquid with a temperature of up to 80 degrees, a cast-iron casing with horizontal connectors along the axis of the shaft is provided. Replaceable O-rings made of cast iron. The pump shaft is made of steel and rotates on one thrust and radial bearings with ring lubrication.
The glands are equipped with a water lock, which is carried out using tubes that supply fluid from the spiral chambers. Such a cantilever single-stage centrifugal pump has a capacity of 30 to 1800 liters per second and a head of 10 to 100 meters.
Vertical Shaft Installations
Two brands of single-stage devices for clean water are produced: 20 HB and 28 HB. They are designed for installation in buried stations. In this installation, the heel of the electric motor perceives axial forces. A soft-packed hydraulic shutter is provided on the pump seal. Installations of type HB are directly connected to electric motors or by means of solid folding couplings through an intermediate shaft. The vertical single-stage centrifugal pump has a capacity of 3240 to 10 800 cubic meters per hour and a head of 29 to 40 meters.
Features of sewage pumps
A single-stage centrifugal pump is used for pumping sewage, sewage and sludge. One of the main reasons for stopping the pumps during use is their clogging. To protect against ingress of debris into the mechanisms, special grates are provided. Their installation necessitates a change in the shape of the installation.
Such pumps are sealed with steel rings with a sharp edge cutting the fibers that fall into the seals. The units are equipped with covers providing easy access for cleaning the suction part of the impeller. The number of blades is minimized to reduce the possibility of clogging. The passages between them are thus increasing. Quite often, the number of blades is reduced to two.
The cantilever single-stage centrifugal pump of the sewer type is created from materials that are not susceptible to corrosion. In its housing there are several connectors necessary for partial disassembly during the cleaning process. The leading edges of the blades are rounded off very much. Due to this, the fibrous bodies on them will not get stuck.
Pumps brands NF, NFuV and FV. Open and diagonal devices
The following unit sizes are provided: 2NF, 4NF, 6NF, 8NF. Their productivity ranges from 36 to 864 cubic liters per hour with a pressure of 6.5 to 50 meters. Similarly to such installations, sewage pumps with an open impeller with two thick blades can be used. In such devices, all fibers are cut by the sharp edge of the scapula.
To work with wastewater, a diagonal type single-stage centrifugal pump is often used. The impeller in these installations, as well as in models of the PV and NFuV brands, is equipped with two blades. Their productivity varies from 43 to 150 cubic meters per hour, and the pressure reaches 63 m.
Dredgers
Dredgers are used during pumping through mixtures of loosened mass of soil and liquid to the required distance. Today, the market produces pumps with a transportation range of up to 5 km and a capacity of 40 to 1200 cubic meters per hour. With the help of dredgers, you can develop dredges up to 15 m deep below the water horizon. These plants have a number of features due to the large concentration of large particles in the pumped water mass. For this reason, a wear-resistant wheel is made of manganese solid steel.
The single-stage vertical centrifugal pump is protected by armor on the inside of the housing to prevent rapid wear. So that the mechanism does not deteriorate so quickly, purified water is supplied between the wheel to the left cavity and the oil seal by special drilling to wash out solid fragments from these places.
Radial vanes are installed on the outside of the working and covering wheels of the wheel. They are selected so that the axial amplifier comes into equilibrium during rotation.
Vacuum pumps
A single-stage centrifugal pump with a vacuum device is created in two main versions: dry, suctioning only gas, and wet, which also works with liquid. The difference can only be determined by the distribution nodes. Wet pumps have a much larger dead space, so they have higher ultimate pressure compared to dry ones. The highest speed during operation is achieved by samples with a vertical shaft.
Non-self-priming device
Non-self-priming single-stage centrifugal pump is used for pumping milk or other viscous food products, the temperature of which does not exceed 90 degrees. The impellers of the wheel are closed and each part of such a unit in contact with the liquid is made of good stainless steel and other materials approved for use in the food industry. The engine is protected from water by a special casing.
Conclusion
A centrifugal single-stage pump, the circuit of which is described in this article, can be used in various fields. The operating characteristics of such plants, as well as the material from which the parts are made and the method of their placement in the mechanisms will depend on the method of application and the materials pumped. Pumps can be used for distillation of pure water, a mixture of liquid and dirt, sewage and food masses of various viscosities.
The mechanisms designed for pumping liquids used in food are made of high-quality materials, the use of which is allowed by the Ministry of Health. The pumps that are used to drain sewage fluids containing large fibers are designed so that large parts are dissected and do not interfere with the normal operation of the mechanisms.