Vacuum pump rotary dry type. Vacuum pumps. Scroll vacuum pump

Basic the principle of any type of vacuum pump- it's a repression. It is the same for all vacuum pumps of any size and for any application. In other words, the principle of operation of the vacuum pump is reduced to the removal of the gas mixture, steam, air from the working chamber. During displacement, the pressure changes and the gas molecules flow in the required direction.

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Two important conditions that the pump must fulfill are to create a vacuum of a certain depth by pumping out the gaseous medium from required space and do it within the given time. If any of these conditions is not met, then you have to connect an additional vacuum pump. So, in case of failure to provide the required pressure, but for the required period of time, the fore vacuum pump is connected. It additionally reduces pressure so that all the necessary conditions. This principle of operation of a vacuum pump is similar to a series connection. Conversely, if pumping speed is not achieved, but the desired vacuum level is achieved, then another pump will be required that will help to achieve the required vacuum faster. This principle of operation of a vacuum pump is similar to a parallel connection.

Note. Depth of vacuum created vacuum pump depends on the tightness of the working space, which is created by the elements of the pump.

To create a good tightness of the working space, a special oil is used. It seals the gaps and completely covers them. A vacuum pump having such a device and principle of operation is called an oil pump. If the principle of the vacuum pump does not involve the use of oil, then it is called dry. Dry vacuum pumps have an advantage in use, as they do not require maintenance with oil changes and so on.

In addition to vacuum pumps for industrial use, small pumps that can be used at home are widely used. These include a manual vacuum pump for pumping water from wells, ponds, pools and more. The principle of operation of a manual vacuum pump is different, it all depends on its type. There are different types of manual vacuum pumps:

1. Piston.
2. Rod.
3. winged.
4. Membrane.
5. Deep.
6. Hydraulic.

Piston vacuum pump works due to the movement of a piston inside it with valves in the middle of the body. As a result, the pressure decreases, and the water through the bottom valve rises while the piston handle moves down.

Rod vacuum pump similar in principle to the piston, only the role of the piston in the body is played by a very elongated rod.

vane vacuum pump has a completely different principle of operation. The pressure in the working chamber of the pump is created by the movement of the impeller with blades (impeller). In this case, the water rises along the wall of the chamber, this increases the pressure and the water splashes out.

A more complex design is rotary vacuum pump. But this complexity is offset by the fact that the pump's capabilities include pumping not only water, but also heavier oily liquids. The pressure in the pump is created by a rotor with thin plates that rotate and use centrifugal force to draw liquid into the container, and then push it out by physical force.

Diaphragm vacuum pump does not have any rubbing parts, so it can be used for pumping very dirty mixtures. With the help of an internal pendulum and a membrane, a vacuum is created that moves the liquid through the body to the desired location. To prevent the body from jamming from accidentally lingering debris, the pump is equipped with special valves that clean the pump.

Deep vacuum pump capable of lifting water from very great depths (up to 30m). The principle of its operation is the same as that of the piston, but with a very long rod.

Hydraulic vacuum pump it pumps viscous substances well, but it has not received wide application. We will consider in more detail the principle of operation and the device of vacuum pumps on its individual types.

The principle of operation of liquid ring vacuum pumps

One of the types of vacuum pumps is a water ring vacuum pump, its principle of operation is based on creating a tightness of the working volume with the help of a liquid, namely water.

Let us consider in detail the liquid ring vacuum pump and its principle of operation. Inside the body of the liquid ring pump there is a rotor, which is slightly offset from the center. On the rotor is placed Working wheel with blades rotating during operation. Water is pumped inside the body. When the wheel moves, the blades capture water and throw it away towards the hull by centrifugal force. Since the rotation speed is high enough, as a result, a water ring is formed around the circumference of the body. In the middle of the case, free space is obtained, which will be the so-called working chamber.

Note. The tightness of the working chamber is ensured by the water ring surrounding it. Therefore, such pumps are called liquid ring vacuum pumps.

The working chamber turns out to be sickle-shaped, and it is divided by the blades of the wheel into cells. These cells are obtained different sizes. During the movement, the gas moves alternately through all cells, heading towards a decrease in volume and simultaneously compressing. This is how it goes a large number of times, the gas is compressed to the required size and exits through the injection port. When the gas passes through the working chamber, it is purified and comes out clean. This property proves to be very useful for pumping contaminated media or saturated with steam gas environments. The vacuum pump constantly loses a small amount of working fluid during operation, therefore, the design of the vacuum system provides a reservoir for water, which then, according to the principle of operation, returns back to the working chamber. This is also necessary because the gas molecules, when compressed, give up their energy to the water, thereby heating it. And to avoid overheating of the pump, the water is cooled in such a separate tank.

You can see in detail how the liquid ring vacuum pump works and how it works in the video below.

Operation of rotary vane pumps

The rotary vane vacuum pump is one of the oil pumps. In the middle of the body there is a working chamber and a rotor with holes, which is located eccentrically. Blades are installed on the rotor, which can move along these slots under the influence of springs.

Having considered the device, now consider the operating principle of rotary vacuum pumps. The gas mixture enters the working chamber through the inlet, moves through the chamber under the influence of a rotating rotor and blades. The working plate, repelled by a spring from the center, covers the inlet, the volume of the working chamber decreases, and the gas begins to compress.

Note. During gas compression, condensation may occur due to saturation of the steam.

When the compressed gas escapes, the resulting condensate also escapes with it. This condensate can adversely affect the operation of the entire pump, therefore, in the design of rotary vane pumps, it is still necessary to provide for a gas ballast device. You can schematically see how a rotary vane vacuum pump works, its principle of operation, in the figure below using the Busch R5 pump as an example. As already mentioned, a rotary vane pump is an oil pump. Oil is necessary to eliminate all gaps and gaps between the blades and the housing, and between the blades and the rotor.

The oil in the working chamber is mixed with the air, compressed and released into the oil tank. The lighter air mixture passes into the upper chamber of the separator, where it is finally cleaned of oil. And the oil, the weight of which is greater, settles in the oil container. From the separator, the oil returns to the inlet.

Note. High-quality pumps purify the air very thoroughly, there is practically no oil loss, so it is extremely rare to add oil to such pumps.

The principle of operation of the pump VVN

VVN is a water vacuum pump, the principle of operation of which is the same as that of a water ring vacuum pump.

The working fluid of VVN pumps is water. In the diagram you can see the simple principle of operation of the VVN pump.

The movement of the VVN pump rotor occurs directly by the engine through the coupling. This provides high speed rotor, and as a result, the possibility of obtaining a vacuum. True, VVN pumps can only create a low vacuum, which is why they are called pumps. low pressure. Simple VVN pumps can pump gases, steam-saturated polluted environments, and at the same time purify them. But the composition must be non-aggressive so that the cast-iron parts of the pump are not damaged as a result of reaction with the chemical composition of the gas. Therefore, there are models of VVN pumps, the parts of which are made of a titanium alloy or a nickel-based alloy. They can pump out a mixture of any composition without fear of damage. The VVN pump, due to its principle of operation, is performed only in a horizontal version, and the gas enters the chamber from above along the axis.

Today there are many physical and chemical processes carried out in a vacuum environment. To create it, vacuum pumps of various types and types are used. They are divided according to the type of work, technical capabilities, functional purpose. To date, manufacturers of vacuum equipment produce volumetric and non-volumetric pumps.

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Volumetric mechanical installations carry out pumping of air due to the action of moving working elements. They carry out a gradual compression of air with a decrease in the volume of the chamber. This type of pumps includes installations with diaphragm, rotary vane, water ring, cam and spiral working element. As a rule, they are used to create low and medium vacuum, which is equal to 10-2 mm Hg. Art. Some units are capable of generating high pressure.

The rest of the pumps do not use mechanical principle work in which gases are exposed to low temperatures or other phenomena that contribute to the creation of a vacuum. Pumps of this type used to create high and ultra-high vacuum. These include diffusion, steam-oil, multiply charged, getter, getter-ion and other pumps. However, most of these pumps work in conjunction with foreline pumps to provide required pressure. They are necessary to create a preliminary discharge and are represented by all types of mechanical pumps.

Domestic vacuum pumps

Domestic vacuum pumps, unlike foreign units, have large dimensions, are made of high quality materials, are highly productive, and reliable. They can be used in various industries, as well as in agriculture. Domestic samples of the same series have similar designs, while they have many modifications. Most of the pump elements are suitable for other models, so they have a high maintainability.

The most common models that are produced in our country include installations of the NVR and VVN series. They are widely used in various systems, but differ significantly in their design. These models have many modifications that differ in size, main performance indicators, and residual pressure. HBP units use mineral and semi-synthetic vacuum oils, which are designed to seal gaps. In VVN pumps, additional lubricating elements are not used due to the fact that this function is performed by the working fluid, which, as a rule, is represented by water.

Vacuum pumps NVR

HBP vane vacuum pumps are used to create low medium and high vacuum. A wide range of installations allows them to be used in industrial, agricultural, woodworking, food and other enterprises. The units are distinguished by the fact that they are able to create a vacuum with a high residual pressure for short term. HBP pumps are versatile because they can perform various types of tasks.

The model range is represented by such units as NVR-0.1D, 2NVR-0.1D, 2NVR-0.1DM, NVR-1, NVR-4.5D, 2NVR-5DM, 2NVR-5DM1, 2NVR-60D, 2NVR-90D , 2NVR-250D. The units can have single-stage and two-stage type of operation, be modified with a gas ballast valve and have different capacities. Installations of this type can perform effective pumping only if the vacuum system is completely free of dust, dirt and condensate.

Vacuum pumps VVN

Vacuum pumps model range VVN differ significantly from other pumps in that the system uses liquid during the operation. As a rule, water is used in this capacity. Pumps have a narrower functionality, but are indispensable in many areas of activity.

The main advantages of water ring vacuum pumps VVN:

• able to clean the pumped mixture;
• applicable in systems with mechanical contamination;
• ecological cleanliness;
• lack of vacuum oil in the system;
• ease of use and maintenance;
• low power consumption;
• maintainability;

VVN vacuum pumps are used in the food, chemical, medical, pulp and paper, microbiological, agricultural, woodworking, pharmaceutical and perfume industries.

Vacuum pumps for industrial furnaces

In industrial furnaces, vacuum pumps are used to speed up annealing, normalizing, hardening, and improving material quality. In a vacuum space, all chemical and physical processes are carried out quickly and efficiently.

Vacuum pumps can be used in industrial furnaces of arc, induction, thermal, hydrogen type. Often, to ensure a low residual pressure, diffusion furnaces are used, which have a non-volumetric type of operation.

In order to effectively perform heat treatment in an industrial furnace, pumps must be used that provide sufficient pumping speed. It also allows you to count on high performance. An equally important indicator is the residual pressure, but it can vary significantly in various ovens on the type of operation being performed.

Vacuum pumps for climatic chambers

Climatic chambers are equipment that is necessary for the study of the qualities various materials and aggregates. Vacuum pumps are used in the installations for efficient and fast operation.

In order to use the pump in a climate chamber, it must be:

• withstood high/low temperatures;
• high humidity;
• create a sufficient level of vacuum;
• had the ability to create and maintain the necessary pressure.

Rotary vane vacuum pumps

Rotary vane pumps are excellent for industrial applications. Wide Range models allows you to perform various types of operations. Installations with high residual pressure and speed are used for climatic chambers and heat treatment furnaces.

Installations have high reliability, wear resistance, maintainability. They can be classified among universal means creating a vacuum. At the same time, to ensure their operation, it is necessary that the vacuum system be cleaned of mechanical impurities and moisture. For operation in climatic chambers, pumps made of of stainless steel.

Vacuum pumps for degassing chambers

Degassing is a process that cannot take place without the participation of a vacuum pump. But it performs the main task of pumping gases and gas mixtures from various materials. To perform the pumping of gases and vapors from dense materials, as a rule, two-stage vacuum pumps are used.

Two Stage Vacuum Pump

The two-stage vacuum pump is an upgraded model single stage pump with higher performance. This type of installation is widely used in production areas where it is necessary to create a higher pressure. At the same time, they are reliable and can be used with various types gases.

In two-stage vacuum pumps, the chambers are dependent on each other. This helps to synchronize, and therefore increase productivity. Every year they are gaining more and more popularity due to the fact that they practically do not have large dimensions, but at the same time provide the best technical performance.

Dry vacuum pump

Dry vacuum pumps are becoming increasingly important because they are able to pump out the system without contamination. Unlike other units, they do not use an oil seal.

They have lower performance than analog units, but they are quite reliable. For efficient and proper operation, it is necessary to carry out periodic maintenance with the replacement of plates, which may wear out during operation.

Oil Free Vacuum Pump

Oil-free vacuums are used in enterprises where it is necessary to ensure the cleanliness of the operation. I use them very often laboratory research where it is necessary to create a sufficient level of residual pressure in a short time. Installations have high reliability and maintainability.

In the manufacture of this type of pump, designers make careful calculations, since it is important that there are sufficient gaps between the elements that will avoid friction, but not be so large as to allow a significant reduction in performance.

High Vacuum Pumps

The creation of a high vacuum, as a rule, occurs using several pumps, including a fore-vacuum and a high-vacuum unit. The fore-vacuum pump, represented by one of the volumetric units, performs preliminary discharge, pumping out up to 97% of gases, and the high-vacuum pump performs the rest of the work, reaching the limit values.

The following can be used as high vacuum pumps:

• turbomolecular;
• diffusion;
• ionic;

Turbomolecular pumps

Turbomolecular pumps are significantly different from other pumps high pressure. They are able to independently create a high vacuum, since they have a mechanical principle of operation. The settings operate in the range 10-2 - 10-8 Pa. The main working mechanism is represented by a stator and a rotor with disks that are located at a certain angle.

Molecules of the gas mixture, being in a turbomolecular pump, significantly increase the speed of movement due to collision with each other. The rotor rotates at a speed that exceeds 10,000 revolutions, which is the main reason for creating high pressure.

Ion vacuum pump

Ion or getter ion vacuum pumps were in widespread use before the advent of other high vacuum pumps. With their help, a pressure equal to 10-6 mbar is created. Today they are used less frequently, but still find their consumer. Pumps of this type are distinguished by environmental friendliness and an advantageous method for obtaining ultra-high vacuum.

In the installation, the molecules are captured and bound by gases or a getter layer, and then held in the volume of the installation. They are able to hold a vacuum even when not in use. The main element of the pump is the chamber and other fixed elements. The ion pump consumes a small amount of electricity and has low noise.

Extremely reliable and efficient dry vacuum pumps, claw and screw pumps are widely used in general industrial processes, as well as for creating vacuum in explosive and corrosive environments.

The world leader in the design and manufacture of "dry" vacuum pumps is the English company Edwards. It is Edwards that is a pioneer in the field of dry gas pumping. With over 90 years of experience with vacuum pumps in a wide range of applications, including processes with high levels of dust and contamination, and over 150,000 dry vacuum pumps shipped worldwide, we provide the ultimate dry vacuum solution.

Dry pumping technology provides a significant reduction in operating costs, increased productivity, improved product quality, as well as the creation of more favorable working conditions in the workplace. This technology guarantees high levels of reliability in situations where oil sealed pumps are at the edge of their operating range. "Dry" pumps are capable of pumping fluids with the highest allowable water vapor pressure at the pump inlet, which is several times higher than the highest water vapor pressure for oil-sealed pumps, and they do it in the absence of any contamination. This capability makes the pumps ideal for vacuum pumping in drying processes and other industrial applications.

Patented by Edwards in 1984, Drystar's claw-grip dry vacuum technology was an innovation in the world of vacuum in its time and continues to enjoy well-deserved popularity all over the world to this day.

So, the first models of Edwards pumps, with a claw mechanism, of the Drystar trademark were the pumps of the GV series, which are now installed all over the world in a wide variety of general industrial processes, in metallurgy, in drying processes, surface treatment, and the production of semiconductor devices. The principle of operation of the GV pumps is based on the claw mechanism of the gripper, and the additional Roots stage used in the design of the pumps allows you to increase the speed of pumping in the operating range and achieve maximum speed of action.

The experience accumulated during the development of dry claw pumps was used in pumps of the EDP series, the main difference of which from the pumps of the GV series is the vertical direction of the flow of the pumped medium, due to which, if liquids enter the working volume, they immediately drain from the pump without affecting it. Wherein heat, maintained inside the pump, avoids the condensation of media, including chemically active ones, and as a result, the effects of corrosion. Thanks to this feature, the pumps of the EDP series optimally satisfy high requirements technological processes chemical and pharmaceutical industries.

In parallel with the technology of dry pumping with a claw mechanism, the technology of vacuuming with helical pump rotors was developed.

The IDX series screw pumps are ideal for applications requiring high performance in vacuum or fast pumping atmospheric pressure. The pumps use a unique double-ended symmetrical screw mechanism that simplifies the shaft expansion compensation system. This design, which has no analogues in products from other manufacturers, makes it easy to pump gaseous media with a high content of dust. It is important to note that the pump can be used as a backing pump in a multi-stage vacuum system. Systems based on IDX pumps are the standard solution in steel degassing processes.

Later, by analogy with the advent of the "chemical" versions of the GV-EDP pumps, the CDX screw pump was developed, which is a modification of the IDX pump, but has a number of features that allow it to be operated in chemical and petrochemical industries.

In combination with the EH/HV/SN booster pumps, dry vacuum pumps of the GV, EDP, IDX series can achieve capacities up to 120,000 m3/h. As a special case - systems based on IDX for metallurgy, which are ready-made solutions for "furnace-ladle" systems for 50, 100 and 150 tons (VD vacuum degassing and VOD vacuum decarbudization processes). The pumping speed can be changed by adding additional stages, which allows you to design vacuum systems that meet the needs of a particular process.

At present, a new generation of vacuum pumps for general industrial processes, the GXS screw type pump, has become actively used. This pump is a complete turnkey solution, the pump is ready to work immediately after delivery. It is equipped with a control panel located directly on the case, and also has a number of additional options that allow you to configure a system that fully meets the needs of a particular customer. The wide range of GXS pumps is available both in single stage pump form factor and in combination with a booster pump (in a single housing) to provide capacities from 160 to 3’500 m3/h.

Currently, Edwards does not leave without his close attention evacuation processes in the chemical and pharmaceutical industries. So, based on the GXS, the pumps of the CXS series were developed. The main difference between this pump and the GXS is that all elements electronic system pump controls are placed in a separate explosion-proof unit.

You can learn more about the capabilities and characteristics of Edwards dry vacuum pumps in the relevant sections of our catalog.

Innovative development of the manufacturer Edwards - pumps of the EDS series for complex technological processes in the chemical, petrochemical and pharmaceutical industries

A turbomolecular pump (TMP) refers to special pumps that allow creating and maintaining a deep vacuum for a long time, on the order of 10 -2 to 10 -8 Pa. Of interest is the etymological meaning of the name of the pump. The prefix "turbo-" is an abbreviated version introduced into the technical lexicon since 1900, the term "turbine". These two words come from the French. "turbine" - "turbine", and earlier from lat. "turbo", meaning "disorder, disturb, whirlwind, spinning top". The second part of the first word “- molecular” comes from lat. "molecula" - "part, particle", as a diminutive of "moles" - "mass, lump, bulk." The following term “pump” is originally ours, Slavic, as it was transformed from the Old Orthodox words “suck, ssati, ss”, meaning “suck breast milk”, “suck on the brain bones”, “pull out liquid”.

In this article, we will look at:

• pfeiffer turbomolecular pump;
• agilent tv81m turbomolecular pump;
• high vacuum turbomolecular pump twistorr 84 fs;
• turbomolecular pump tg350f;
• power supply unit for turbomolecular pumps type bp 267;
• turbomolecular pump working principle;
• molecular vacuum pump;
• molecular pump mdp 5011 price;
• buy a turbopump;
• turbopump price;
• disadvantages of turbopumps;
• turbomolecular pump tmn 500;
• pump tmn 200;
• dry pump;
• oil-free vacuum pump;
• oil-free foreline pumps;
• dry type vacuum pump;
• oil-free rotary vane vacuum pump;
• vacuum piston oil-free pump;
• foreline pump 2nvr 5dm.

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In 1913, the German scientist Wolfgang Gaede published in the journal Annalen der Physik a description of a new vacuum pump, for which the laws of the molecular-kinetic theory of gas movement were used. For the purpose of experimental verification, he manufactured the first vacuum molecular pump with a minimum gap of 0.1 mm between the rotor rotating at a speed of about 8000 rpm and the stationary stator. Gas rarefaction up to 10 -4 mm was obtained mercury column. New pump even began to be produced by the German company Leybold's Nachfolgers, but did not receive wide distribution. Firstly, there was no urgent need for it, and secondly, technological difficulties with the manufacture of such small gaps interfered. The ingress of macroscopic solid particles (pebbles, chips, glass) into the pump together with the gas caused the rotor to jam.

In the late 1950s, interest in molecular pumps resumed.

Only at the end of the 1950s did interest in molecular pumps resume, when the German engineer W. Becker invented the Pfeiffer turbomolecular vacuum pump with a large number bladed discs on the shaft and with increased clearances, about 1 mm. This pump was patented in 1957 by Pfeiffer Vacuum. Further, the device and principle of operation of TMN pumps continued to be improved, such designs as the Agilent TV 81M turbomolecular pump and the latest (2015) high-vacuum turbomolecular pump Twistorr 84 FS by the Italian company Agilent Technologies, the TG 350F hybrid turbomolecular pump by the Japanese company Osaka Vacuum and others appeared. In this case, often the nodes of these devices are interchangeable. For example, a power supply unit for a turbomolecular pump of the BP-267 type can be used for pumps of the NVT-340, NVT-950, 01AB-450, 01AB-1500 models.

In a molecular pump, the gaseous medium is pumped out due to the communication of mechanical energy impulses to the substance molecules from the solid, liquid, gaseous surfaces of the pump moving at high speed. At the same time, in a molecular pump, the directions of movement of working surfaces and gas molecules coincide, and in a turbomolecular pump, the directions of movement of working elements and molecules are mutually perpendicular.

Molecular pumps according to the principle of operation are divided into:

• mechanical (rotary and turbine);
• ejector;
• steam jet;
• gas jet;
• water jet;
• diffusion.

For example, the high vacuum molecular pump MDP 5011 is a device with mechanical working elements. The movement of gas molecules to the outlet pipe of the pump provides a solid surface of the rotor-glass, which makes 27,000 rpm. This model MDP 5011 is the bestseller among turbopumps. Clearly, you are interested in the price of the MDP5011 molecular pump. Please contact us with questions, call, write to e-mail. We will advise and help.

The turbopump is pumping device driven by a turbine, the components and parts of which are included in the design of the pump. There are the following types of turbopumps depending on the type of pumped working medium.

1. Turbopumps for pumping liquids.
2. Turbopumps for pumping suspensions.
3. Turbopumps for pumping gases.

The disadvantages of turbopumps include the complexity of the design, long downtime when repairing a pump or turbine, high price. Therefore, if you need to buy an oil turbo pump ТМН-6/20, naturally, the question arises, what is the price of a turbo pump. If it does not suit you in other firms, come to us.

Turbomolecular pumps (TMP) are made in the form of multi-stage axial turbines, which ensure the achievement of medium, high and ultra-high vacuum. The special design of the rotor and stator stages of the turbine, in which inclined channels arranged mirror to each other, makes it possible to efficiently pump out gas molecules due to the different probability of molecules passing through channels located at an angle in the pumping and supply directions. TMPs are fixed on a massive base through shock absorbers, which reduces vibration during pumping.

The principle of operation of the turbomolecular pump is as follows. The energy of the turbine blades rotating at high frequency is transferred to the gas molecules. The latter collide with the surfaces of the blades, move together for a fraction of a second and fly off tangentially to the rotating turbine. There is a summation of the kinetic energy of the blades with the thermal energy of moving gas particles. Chaotic motion of molecules turns into accelerated motion in a given direction of pumping. Such effective rotor action is possible only in the molecular gas flow mode, which is created by an additional low pressure fore vacuum pump.

A good impression is made by domestic double-flow oil-free pumps: the turbomolecular vacuum pump TMN-500 and the TMN-200 pump with a capacity of 500 and 200 l / s, respectively. Of course, in terms of build quality and design they are inferior to foreign counterparts. But at a low cost, they are characterized by reliability in operation, non-failure operation and sufficient durability.

A dry vacuum pump (oil-free) works in the same way as an oil pump. But in a dry type pump, oil is not used to lubricate the rubbing parts, and there are no sealing devices. Therefore, not metal, but a graphite composite material is used as the material for the blades of dry pumps. Graphite blades are cheaper than metal blades made of titanium, aluminum, stainless steel, they are characterized by a lower coefficient of friction and reliably seal the pump chamber.

Advantages of the vacuum oil-free pump:

• absence of oil vapors when air leaves the pump, workplace becomes clean, improves the ecology of the environment;
• no need to purchase and fill in expensive oil, monitor its level and pollution;
• lower cost.

Dry pump disadvantages:

• the depth of the created vacuum is lower than that of oil-sealed pumps;
• the durability of graphite blades is much less than metal ones;
• wear products in the form of powdered graphite enter the atmosphere.

However, experts believe that oil-free vacuum pumps are the future. And now they are trying to buy oil-free rotary vane vacuum pump, oil-free piston vacuum pump, oil-free foreline pump, regardless of their price. Since the simpler and cheaper operation of a dry pump will pay off all the initial costs.

A fore vacuum pump is a device for creating an initial rarefaction of a gaseous medium - a fore vacuum (from German "vor" - "before, ahead" of vacuum and Latin "vacuus" - "empty"). The principle of operation is that the fore-vacuum pump is installed as the first stage in the system of pumps that create high and ultra-high vacuum. Provides energy savings and improves the ability to operate the next high stage pump.

The most suitable for this is the domestic rotary vane fore vacuum pump 2NVR-5DM, designed both to create low and medium vacuum independently, and as an auxiliary pump.

If you are interested in the described turbomolecular and backing pumps from our company's range, you can get more detailed information at consultants. Our highly qualified specialists will help you choose the best option pumps, explain the terms of purchase, operation and service, justify prices. They will assist you in the selection of spare parts and auxiliary materials, such as blades for Becker oil-free pumps, oil for the foreline pump and others. Call our phones or contact by E-mail. We will be glad to help you.

Plunger (piston) vacuum pumps. Bypass devices. harmful space

A plunger vacuum pump is a type of mechanical vacuum pump that is capable of compressing gases to atmospheric pressure. Such a device has a device similar piston compressor double action. The main difference is that the plunger vacuum pump has a higher compression ratio.

Left - initial stage, 2 positions in the center - intermediate stage, right - final stage

The plunger includes a cylindrical part that encloses the eccentric and a hollow rectangular part that moves freely in the hinge slot. When the flat part of the plunger rotates, the pivot also rotates freely in the seat of the pump housing. This plunger is equipped with a channel through which gas enters the pumping chamber from the pumped-out cavity. Entry of the oncoming gas flow into entrance part of the pump is limited by the preliminary closing of the inlet when the spool moves. There is also the possibility of reducing the harmful space. The tightness of the contact of the rotor with the cylinder in pumps is ensured by the fact that a thick layer of oil is formed in the wedge between the rotor and the cylinder.

Mechanical vacuum pumps carry out pumping of the volume, starting from the level of atmospheric pressure. Due to the fact that the pumped gas is released into the atmosphere, relative to mechanical vacuum pumps, such characteristics as the highest working pressure, as well as the highest starting and exhaust pressure, are not used. The key features of oil sealed mechanical vacuum pumps are:

• ultimate residual pressure;
• speed of action.

Mechanical vacuum pumps

A mechanical vacuum pump is a gas removal unit that is used to obtain / maintain a pressure below atmospheric in tanks, from where the working fluid is pumped out at certain intervals at a certain composition and size of the gas flow.

The work is pumping unit based on the fact that the gas moves as a result of mechanical movement working parts of the pump, thereby performing a pumping action. The volume, which is filled with gas, is cut off from the inlet and moves to the outlet. The gas is systematically moved to the outlet of the pumping unit as a result of the momentum of movement, which is transmitted to the gas molecules.

In accordance with the design features and method of operation of this type of pump, seven types of pumps are distinguished (screw / diaphragm / piston / rotary vane / spool / roots / spiral). In accordance with the type of working fluid, mechanical pumps can be molecular (they function due to the flow of molecules of the substance) and volumetric (they function due to the laminar flow of the substance). Mechanical vacuum pumps are differentiated according to the level of vacuum concentration (high, low, medium). Besides, this species pumps are divided into those that can function without lubricant and with lubricant.

This type of pumping units is used in various industries: chemistry, metallurgy, electronics, food industry, medicine, aerospace. Mechanical vacuum pumps are also used in a wide variety of applications. industrial installations, as well as in technical processes (for example, remelting of metals, deposition of thin films, modeling of space conditions, etc.).

Due to the growing demand for pumping units, mechanical vacuum pumps are continuously improved and developed, pumping units with improved performance are being developed.

The speed of operation of such pumps does not depend on the type of pumped gas. The residual pressure depends on the design of the pumping unit and the properties of the working fluid. The working fluid, as a rule, is oil, which has a list of necessary characteristics:

• low acidity;
• viscosity;
• good lubricating properties;
• low saturated vapor pressure in the operating temperature range of the pump;
• low absorption of gases and vapors;
• viscosity stability with temperature changes;
• high strength of a thin (0.05-0.10 mm) oil film capable of withstanding a pressure difference in the gap equal to atmospheric pressure.

The stability of the characteristics of mechanical vacuum pumps depends on the size of the gaps between the surfaces, the number of these gaps, as well as the quality of the oil that lubricates the rubbing surfaces.

The plunger vacuum pump can be equipped with a bypass device to increase efficiency. Bypass devices may differ structurally. Their function is to equalize the pressure on both sides of the piston at the end of the piston stroke.

In the absence of these channels, the remainder compressed gas from the harmful space expands as the piston moves from left to right. In this case, the rest of the compressed gas has a pressure level p2. Curve ea 1 up to suction pressure p1 And p1 And λ 0 \u003d V 1 / V. In a vacuum pump, at the extreme left position of the piston, the rest of the gas moves to the right cavity of the cylinder, where the pressure is equal to p1. The pressure in the harmful space drops from p2 before p in, and the rest of the gas expands along the curve fa. Suction begins at the very beginning of the piston stroke ( λ 0 \u003d (V "1 / V)> λ 0). A similar process occurs when the piston moves in the opposite direction (from right to left). As a result, the volumetric efficiency increases from 0.8 to 0.9 λ 0 .

Presence of harmful space is the reason why a piston vacuum pump is not able to create an absolute vacuum and has a theoretical limit of this value, which corresponds to a certain residual pressure p pr. Value p pr more in the absence of bypass than in the presence of it.

If the vacuum pump operates continuously, then the volume of sucked gas is equal to the volume of process gases emitted into the atmosphere and the volumes that are sucked in from the outside through leaky areas do not change with time. The power indicator on the shaft of the vacuum pump is also not subject to change. It should be noted that this parameter is many times higher for machines equipped with a bypass, because the work of expanding the bypassed amount of compressed gas is lost.