Due to its distinctive characteristics and convenient design, the vane pump has become widespread in various industrial fields. It is used in the pharmaceutical, chemical, cosmetic industries, as well as in the food industry - for pumping condensed milk, molasses, and glaze.
The design includes a heating jacket for pumping substances that acquire a thick consistency at low temperature. The vane pump is used to move many types of liquids: porridge-like, abrasive, with the presence of extraneous small particles, as well as resins and adhesive masses based on them. It is possible to use for pumping through a hose, by lowering the intake pipes into the tank. This device, unlike other types, has an increased suction ability and works with equal effort in both directions.
Design
The basis of the vane pump is as follows:
- The case with the easily demountable device from a strong brand of steel.
- A gear motor having an asynchronous powerful motor.
- A shaft with plates moving along an eccentric trajectory, they are made of bronze or its food substitute.
Near the grooves on the cylindrical surface in the direction of rotation, recesses are made having different angles of inclination at points to the exit of the faces.
Application
The lamellar pump, the average price of which is 30-40 thousand rubles, is a hydraulic machine with volume displacement and working moving vanes with reciprocating motion with respect to the internal elements. It is used as a stationary and mobile unit in mechanical engineering, as well as in agriculture. When pumping liquids with foreign inclusions, it is important to consider that if the permissible particle size is exceeded, they can be retained by the filter on the nozzle.
Vacuum vane pumps release with the right direction of movement of the shaft. Customized left-handed manufacturing is allowed. The mechanism is installed in any position. With the help of an elastic coupling, the drive shaft and the pump shaft are connected. Axial and radial loads cannot be transferred from the drive.
Features
As practice shows, difficulties in extending the period of operation are associated with damage to working plates that are damaged when interacting with abrasive particles that are in the pumped mass. A vacuum rotary vane rotary pump was created for pumping liquids of all kinds, it has a body with a profiled plane, with discharge and intake windows. Among the disadvantages, it is worth noting the decrease in reliability indicators during the transfer of masses with foreign inclusions and various impurities. The transported medium in the course of work passes to the pressure nozzles from the retractors, while foreign particles adhere to the plane of the rotor and the housing. If the dimensions of the elements present in the liquid exceed the maximum permissible limit, there is a possibility of damage to the rotor of the device and the inner surface.
A more advanced design has a plate NPL pump with discharge and absorption windows on internal surfaces. This device has a rotor with grooves, special plates are installed in its cavities, moving in the radial direction. The disadvantage of this design is the uneven wear of the surface of the plates, inner cover, body. The rear working faces and edges wear out unevenly due to pressure drops in the opening chamber and the pressure channel during the transition of the plate to the curve area. In addition, it is worth noting damage caused by the ingress of large particles into the gaps between parts that were not delayed by the channel filter.
The cost of this type of pump starts at 42,000 rubles, it is designed for use in metal-cutting hydraulic drive machines and other devices that require a flow of working fluids, not variable in size, with a steady pressure.
What is required for installation
A safety valve is mounted to protect the hydraulic system and pump from overload. At the same time, its settings must correspond to the nominal pressure at the outlet. The pipeline must have smooth bends and a good seal at the junction with the pump to prevent air from entering.
Before the first start-up, the working mass is poured into the mechanism, and the valve screw is unscrewed to zero settings.
Specifications
The rotary vane vacuum pump is evaluated by the following properties:
- The pumping speed, detected by the volume of gas that passes through the cross section of the pipe at nominal pressure. If the pressure in the system changes, the same thing happens with the pumping speed. The dependence of the speed of action on pressure reveals the feasibility of using the device at a given pressure level.
- Outlet maximum pressure from the outlet. Exceeding it increases the pressure in the inlet. Some vane oil pumps do not emit exhaust gas into the atmosphere. Accordingly, to maintain normal operation, a preliminary vacuum must be formed - this is the minimum pressure reached by this device.
Types of mechanisms
In many ways, the principle of the mechanism’s operation determines the nature of the gas movement in the working pressure range. The gas flow, depending on the sparseness, is carried out in a molecular, viscous or inertial mode. The pump may have a double or single action. In the latter case, a cycle of work takes place in one revolution, which includes the process of suction and discharge. There is also a division into unregulated and adjustable. In the first embodiment, the mechanism can provide a continuous direction of fluid flow; in the second, mechanical adjustment of the valve is required. A single-acting vane pump can have two types of mechanisms. In twofold modifications there is only an unregulated device.
Advantages
Among the positive aspects, it is worth noting the following:
- Easy maintenance.
- Increased reliability.
- Reversibility.
- Durability.
- Almost silent operation.
- Easy installation.
- Profitability.
The arrangement of oil pumps
Spool, plate-stator and rotor options are widespread. The rotary vane vacuum pump has an eccentricly rotating mechanism, in the cavities of which two plates are pressed against the surfaces of the housing. The working volume of the chamber is divided into predetermined parts by the contact points of the rotor, plates and walls, in particular into an intermediate one, which reduces the mass of the inlet and increases when moving. With an increase in volume, rarefaction appears on the inlet side, and gas enters the vacuum mechanism from the chamber. The gas on the inlet side begins to compress and is released when the valve spring pressure is exceeded. The case of the mechanism is located in a container with oil, due to which all gaps are sealed and the possibility of gas backflow is excluded.
Oil types of vane pumps are not intended for pumping gas-vapor mixtures, for example, moist air. Due to the design features, the gas is compressed by the time the exhaust valve opens. In this case, steam even with a small partial pressure in the chamber begins to condense, water mixes with the oil and turns out to be from the inlet side, where it evaporates again. This is the cycle.
Gas ballast
Oil pumps use gas ballast mechanisms to release moist air, which supply atmospheric dry air to the compression volume. Ballast gas ensures that the opening of the exhaust valve begins earlier than the partial pressure reaches the dew point, after which both vapors and gases are released. Gas ballast reduces the ultimate vacuum and reduces the speed of action, but it increases the range of application of the device.
The vane pump requires the use of specialized vacuum oil, in which there are no low boiling fractions due to the use of vacuum distillation. In places of friction, due to overheating, decomposition of oil begins during operation, subsequently light hydrocarbons arise. Thanks to them, the vacuum decreases and the vapor pressure increases.