rotary vane pump working principle

Rotary vane pump is mainly composed of pump body, rotor, rotary vane, end cover, spring and so on. A rotor is eccentrically installed in the cavity of the rotary vane pump. The outer circle of the rotor is tangent to the inner surface of the pump cavity (there is a small gap between them). Two rotary vanes with springs are installed in the rotor groove. When rotating, centrifugal force and spring tension keep the top of the rotor in contact with the inner wall of the pump chamber. Rotor rotation drives the blade to slide along the inner wall of the pump chamber.

The two rotating vanes divide the crescent-shaped space enclosed by the rotor, pump chamber and two end caps into three parts: A, B and C, as shown in the figure. When the rotor rotates in the direction of arrow, the volume of space A connected with the suction port increases gradually and is in the process of suction. The volume of the space C connected with the exhaust port is gradually shrinking, and it is in the exhaust process. The volume of B in the middle space is also gradually decreasing, and it is in compression process. Because the volume of space A increases gradually (i.e. expands), the pressure of gas decreases, and the pressure of gas outside the inlet of the pump is stronger than that inside space A, the gas is inhaled. When space A is isolated from the suction port, that is to say, when it moves to space B, the gas begins to be compressed, the volume gradually reduces, and finally communicates with the exhaust port.

When the compressed gas exceeds the exhaust pressure, the exhaust valve is pushed open by the compressed gas, and the gas is discharged into the atmosphere through the oil layer in the tank. By continuous operation of the pump, the purpose of continuous pumping is achieved. If the exhausted gas passes through the airway and transfers to another stage (low vacuum stage), it is pumped out by the low vacuum stage, and then compressed by the low vacuum stage and discharged into the atmosphere, a two-stage pump is formed. At this time, the total compression ratio is borne by the two stage, thus raising the limit vacuum degree.

piston vacuum pump overhaul

For the maintenance of piston vacuum pump, it is generally necessary to disintegrate the pump thoroughly, check comprehensively, measure the clearance between the sliding valve and the pump body (normal clearance is 0.04-0.12 mm); check whether there are cracks on the surface of the eccentric wheel of the sliding valve and guide rail pump in the pump, replace them immediately; replace all the sealing parts in the pump dynamically; and measure the clearance between the sliding valve and the pump body (normal clearance is 0.04-0.12 mm). A vibration tester can be used to test the vibration of the pump every week.

According to the measured data, the wear condition of bearing, sliding valve and other components can be preliminarily determined. When the accuracy of bearing motion is reduced, it is replaced to avoid the impact and friction between sliding valve and pump chamber caused by the wear of bearing. Vacuum gauge is used to test the limit pressure of the repaired mechanical pump to determine its performance and repairing effect. For old pumps with long service time, the clearance of the pump is greater than 0.1 mm and less than 0.2 mm. The limit vacuum requirement is not very strict. Vacuum pump oil with 150 mm2/s kinematic viscosity can also be selected to meet the normal operation of the pump.

Because of the wear of pump chamber, the gap between slide valve and pump chamber is larger than 0.2mm. It needs to cooperate with the pump manufacturer. According to the wear condition of pump chamber, the slide valve, eccentric wheel and guide rail are specially made to keep normal gap with pump chamber. For the serious wear and scratch of pump chamber, the time of emptying and the limit pressure can not be used. If the cost of spare parts is close to half of the price of the new pump, the value of maintenance has been lost. A new piston vacuum pump should be replaced.


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Roots vacuum pump -Vacuum distillation

Application and improvement of vacuum distillation roots vacuum pump

In order to solve the problems of Roots vacuum pump in distillation engineering, two aspects of technology and equipment are adopted to tackle the key problems together. After analysis and research, our company thinks that we should consider the factor of increasing vacuum. In theory, the increase of temperature will accelerate the speed of resinization of materials, and the long residence time of materials will increase the amount of resin. The best way to solve these two problems is to increase the vacuum degree in the pot.

First, raising the vacuum degree can reduce the boiling point of the material, that is, reduce the bubble point temperature in distillation operation.
Secondly, increasing the vacuum degree can increase the driving force of distillation and speed up the steaming rate of materials.

In the distillation process, the vacuum equipment we used in the past is a common reciprocating vacuum pump. Its performance parameters are the pumping rate of 150 L/S, the limit vacuum degree of 2600 PA and the motor power of 15 kw. The present method is to use Roots vacuum pump with high vacuum degree in series with reciprocating vacuum pump, and the vacuum degree and pumping rate will be greatly improved.

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Vacuum pump

How to reduce the temperature of the suction gas of the vacuum pump?

One of the important sources of sealing water heat of vacuum pump is the air-steam mixture extracted from condenser. Reducing the temperature of mixture can not only reduce the heat entering vacuum pump, but also condensate the water vapor into water as the temperature decreases. The vapor partial pressure decreases and the air partial pressure ratio increases, so it enters the vacuum pump. With the increase of air concentration in the vacuum pump gas, the effective suction capacity of the vacuum pump is improved.

At present, the widely used method is to introduce the lower temperature desalted water or cooling condensate into the air-extracting pipe cooler at the entrance of vacuum pump. The steam condensate water in the mixed gas is mixed with the injected Desuperheater Water and recovered. The non-condensable air is pumped out by vacuum pump. This method is the most economical and reliable because of its simple layout, low investment, no rotating equipment and no maintenance.

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Vacuum system exhaust valve inspection

  Damage to the valve plate of the pump is also one of the common faults. In the case of oil bubbles continuously appearing in the oil window, even a large amount of oil tumbling, the vacuum is very low or the gauge pointer swings back and forth (commonly known as returning gas), which is mostly a valve problem.Vacuum Valves

     The steel plate valve piece is easy to be broken, the pressing screw is easy to loose or unevenly pressed, the oil rubber stripping cloth is easy to be deformed and damaged, and the spring of the large pump pressing the valve piece is easy to be broken. In case of these failures, only need to be replaced. Valves, marbles and other parts can be used. Of course, there are some problems with the valve. It is not easy to have a fox. For example, there is a valve that has a vacuum that is too high or low. It is difficult to check the situation like this, because the performance is not obvious, sometimes it is inter-sexual. According to experience, the pump cavity is deformed, the local micro-leakage, the oil seal film accidentally broken, and the valve sheet can cause the vacuum degree to swing. Therefore, the end cap is first removed, the roundness taper of the pump chamber, the tolerance of the end face, the parallelism of the eccentric wheel, etc., and the result is not large, within the allowable range. After the assembly, the vacuum still oscillates, and it is suspected that the pump body is leaking, so it is painted several times with the shellac paint solution. After the test, it is still not pumped, and you still notice that the valve beat is not too crisp. Slightly uneven, sometimes, it can be seen that several bubbles came out but the valve was not broken. After careful observation, it was found that the valve plate was closed to the air outlet. Upon inspection, it was found that the angle of the valve plate was not correct after installation, that is, it was not parallel with the air outlet.

     At this time, the valve plate pressure plate is fixed at a certain angle, and the valve plate is pressed by a spring, so that the vacuum degree is tested again, the needle is no longer oscillated, and the operation proves that it is indeed repaired. This example is a bit special, indicating that the manufacturing problems will be reflected after a long time of use. Pay attention to this part of the exhaust valve, and always check its working condition frequently because it often has various problems. In addition to the valve plate is easy to break, the valve plate is not tightly loaded, not broken, the rod is loose, the compression nut is loose, the compression spring is broken, the marble is running away, etc., should be carefully checked.Vacuum System

     In operation, care should be taken not to open the pump. Because the pump chamber is full of oil, the pump will break the rotor (especially the high vacuum stage rotor), and the valve will be broken, especially in the air volume. When using many containers, be sure to start the pump step by step or turn the pulley several times with the hand to turn the pump on.Molecular Vacuum Pump Price

Oil-free vacuum pump

The oil-free vacuum pump is a mechanical vacuum pump that can operate without any oil lubrication. The utility model has the advantages of simple structure, easy operation, convenient maintenance and no pollution to the environment. The oil-free vacuum pump has good durability and is a vacuum, compression, dual-purpose vacuum pump. It is a basic equipment with a wide range of applications to obtain vacuum.Rotary Vane Vacuum Pump

Compared with the oil pump, the oil-free vacuum pump has a low vacuum and a small pumping capacity, but is compact in size, easy to install, simple to maintain, easy to move, does not produce soot, and does not pollute the environment, especially in laboratories with higher requirements. It is also one of the most frequently equipped equipment in the laboratory.Dry vacuum pump

Therefore, when purchasing an oil-free vacuum pump, first determine the degree of vacuum required to work. If the demand is high, the vacuum pump selected should be higher than the required vacuum. Otherwise, the vacuum requirement will not be met. Go to work requirements. The second is the pumping rate of the oil-free vacuum pump, which is slightly larger than the required pumping rate during the selection, so that it can better meet the needs. Finally, see if the extracted gas is corrosive, corrosive gas will corrode the pump, and special materials must be used to meet the demand.Oil Diffusion Vacuum Pump 

Vacuum pump manufacturer

Shanghai EVP is a professional vacuum pump manufacturer. If you don't understand the vacuum pump selection, please contact Xiaobian to find out how to choose the vacuum pump:

First, the vacuum volume should be calculated first: check the time required to reach the required vacuum, the flow resistance and leakage of the vacuum piping. Consider the pumping rate required to maintain the vacuum under certain process requirements after achieving the required vacuum.

Second, the type of gas to be pumped and the amount of pumping: check and determine the type of pumping and pumping capacity required by the process. Because if the type of gas being pumped reacts with the liquid in the pump, the vacuum pump system will be contaminated. At the same time, consideration must be given to determining the appropriate exhaust time and the amount of gas produced during the pumping process.liquid ring vacuum pumps manufacturer

Third, determine the working range of the vacuum pump: First, we must check to determine the vacuum degree required for each process. Because each process has its own range of vacuum, it must be carefully studied and determined; determine the ultimate vacuum, check the ultimate vacuum of the vacuum pump system based on the vacuum required to determine the process, because the ultimate vacuum of the system is determined The optimal working vacuum of the system. In general, the system's ultimate vacuum is 20% lower than the system's operating vacuum and 50% lower than the foreline's ultimate vacuum.Dry vacuum pump

Fourth, the general vacuum pump selection requirements :

1. Vacuum degree, vacuum volume, main medium, temperature, and main volume equipment;
2. Vacuum flows into the medium and flow, pressure, temperature, and law;
3. Pumping capacity, extraction of gaseous medium, temperature;
4. The area of ​​the vacuum equipment, the degree of automation, and the specifications of the vacuum piping.