The cantilever single-stage centrifugal pump is designed for pumping stations. In plumbing installations, general-purpose equipment is most often used. For the most part, D-type double-sided pumps are installed at the stations, and if large volumes are required, console devices are used.
The single-stage vertical centrifugal pump is used in underground stations, the construction of which is difficult in conditions of too close water levels. This makes it possible to reduce the cost of construction, reduce the size of the machine room, improve the quality of operating conditions for electric motors that can be moved to the first floor.
Such installations are most often used with large water supplies. Sewage dynamic pumps are mostly installed onstations of systems of removal of household waste. The water temperature is up to 80 degrees and the possible content of up to one percent of abrasive particles is provided. In wastewater systems, installations of the Gr and GrU types can also be used.
Single-stage centrifugal pump and its properties
The operational properties of such pumps are determined by their main parameters: power, head, NPSH, delivery, suction lift. Important qualities of the units are the voltage of the electric motor and the speed of the wheel.
It must be understood 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 regime points correspond to the maximum efficiency. Appropriate set and delivery are acceptable indications for a pump. These characteristics are included in the designation of installations.
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. The single stage centrifugal water pump always operates within the duty cycle, which is determined according to 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 atoptimum atmospheric pressure at ocean level.
Pump types K and KM
The horizontal single-stage centrifugal pump operates with a single-sided impeller located on the edge of the pump shaft. Discharge nozzles rotate 90, 180, 270 degrees. It depends on the specific layout conditions. The bearings in the mechanisms are lubricated with a liquid substance. Cantilever single-stage centrifugal pump can have several modifications: installation without an engine (K) and in a monoblock design (KM). After these letters, the feed and pressure are indicated on the marking.
Units with two-sided supply
Single-stage horizontal pumps of class D with semi-volute inlet are available on the market. The horizontal lifting of the cast-iron body is carried out in the plane of the shaft axis. This feature makes it possible to disassemble and repair the device without the need to dismantle the pipeline. Each double-sided pump is marked with the symbol "D". After this letter, two numbers are indicated: flow and pressure.
What does a console install consist of?
Single-stage centrifugal water pump is composed of volute body, support, front cover, impeller, suction pipe, nut, shaft, stuffing box bush, ball bearing.
The principle of connecting components
Thrust pressure is partially balanced with relief holes. Also, the wheel is supplied with an axial seal on the back side. Tube with nozzleconnects to the pressure relief chamber of the pump. A second ball bearing is installed to secure the rotor and better absorb unbalanced thrust. The pump seals are equipped with a hydraulic seal.
Such installations have a capacity of 28 to 100 liters per second with a head of 12 to 98 meters. High-performance single-stage pumps mostly have the possibility of double-sided supply. With normal thrust, a good dual-flow impeller has fairly high cavitation rates.
Body and seals
Pumps designed to pump clean liquids with temperatures up to 80 degrees have a cast-iron casing with horizontal splits along the shaft axis. Replaceable sealing rings are made of cast iron. The pump shaft is made of steel and rotates on one thrust and radial bearings with ring lubrication.
Seals are equipped with a water seal, which is carried out using tubes that supply fluid from the spiral chambers. This single-stage cantilever centrifugal pump has a capacity of 30 to 1800 liters per second and a head of 10 to 100 meters.
Vertical Shaft Units
There are two brands of single-stage clean water devices: 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. On the stuffing box of the pump there is a hydraulic seal with a soft packing. HB type units are connected directly to electric motors or through solid seamcouplings through the intermediate shaft. The single-stage vertical 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
The centrifugal single stage pump is used for pumping sewage liquid, sewage and sludge. One of the main reasons pumps stop during use is clogging. To prevent debris from entering the mechanisms, special gratings are provided. Their installation necessitates a change in the form of the installation.
Such pumps are sealed with steel rings with a sharp edge that cuts the fibers that enter the seals. The units are equipped with covers that provide easy access for cleaning the suction part of the impeller. The number of paddles is kept to a minimum to reduce the possibility of clogging. The passages between them thus increase. Quite often, the number of blades is reduced to two.
Cantilevered single-stage centrifugal sewer type pump is made of non-corrosive materials. Its body has several connectors necessary for partial disassembly during the cleaning process. The leading edges of the blades are rounded very strongly. This prevents fibrous bodies from getting stuck on them.
Pumps of NF, NFuV and FV brands. Open and Diagonal Devices
The following unit sizes are provided: 2NF, 4NF, 6NF, 8NF. Their performance ranges from 36 to 864cubic 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 blade.
Single-stage centrifugal pump of diagonal type is quite often used for sewage treatment. The impeller in these units, as well as in models of the FV and NFuV brands, is equipped with two blades. Their productivity varies from 43 to 150 cubic meters per hour, and the head reaches 63 m.
Dredge pumps are used when pumping mixtures of loosened mass of soil and liquid through pipes 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, it is possible to develop excavations up to 15 m deep below the water horizon. These installations have a number of features due to the high concentration of large particles in the pumped water mass. For this reason, a wear-resistant manganese hard steel wheel is created.
The single-stage vertical centrifugal pump is protected by armor on the inside of the casing to prevent rapid wear. To prevent the mechanism from becoming unusable so quickly, purified water is supplied through special drillings between the wheel into the left cavity and to the oil seal to flush out solid fragments from these places.
On the outside of the working andthe wheel covering the discs is equipped with radial blades. They are selected so that the axial amplifier comes into balance during rotation.
Single-stage centrifugal pump with a vacuum device is created in two main versions: dry, sucking only gas, and wet, also working with liquid. The difference can only be determined by distribution nodes. Wet pumps have much larger dead spaces and therefore have higher ultimate pressures than dry pumps. The highest rotational speed during operation is achieved by samples with a vertical shaft.
Non-self-priming single-stage centrifugal pump is used for pumping milk or other viscous food products whose temperature does not exceed 90 degrees. The working blades of the impeller are closed and every part of such an installation that comes into 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 facing casing.
The centrifugal single-stage pump, the scheme of which is described in this article, can be used in a variety of areas. The application and materials pumped will affect the performance of such units, as well as the material from which they are made.parts and the way they are placed in the mechanisms. The pumps can be used to distill clean water, mixtures of liquid and dirt, sewage and food mass of various viscosities.
Mechanisms designed for pumping liquids used in food are made of quality materials, the use of which is allowed by the Ministry of He alth. Pumps that are used to remove sewage liquids containing large fibers are designed in such a way that large parts are dissected and do not interfere with the normal operation of the mechanisms.