Vacuum pumps. Water ring vacuum pumps. Types of vacuum pumps and their operating principle Water ring vacuum pump. Design and operating principle
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A vane pump is a mechanism that is very unusual in its structure, which is why many are afraid to buy this type of device. Vane pumps are often divided into two main types:
- Double action
- Single action
Both options operate on the basis of key components consisting of plates and a rotor.
The plates inside the system move exclusively in the radial direction, since only in this way is it possible to achieve the required level productivity. If we talk about the differences between the two categories of vane pumps, then they lie only in the very shape of the stator surface, which is slightly different from each other in terms of its design.
Double acting vane pumps
The stator in such a mechanism most often acts in the form of an oval, which allows the device to operate as evenly as possible. This is achieved due to the fact that all the plates inside the system manage to perform two strokes at once during one revolution of the shaft.
In such a device there is also a certain zone in which the gap between the stator and the rotor is simply minimal. In this section of the system, certain voltage surges may occur, which are dealt with quite well by special sensors that regulate all such issues.
Concerning internal plates, then they are constantly under pressure and pressed against the inside of the working stator. It is this density that allows us to achieve the highest level of tightness, which is also very important for quality work systems.
But this is far from the limit, since turning the stator is just the beginning, after which a similar procedure will be performed several more times. After the rotation continues, a vacuum is formed inside the system, allowing the work process to continue. During this process, the working chamber of the device is already connected to the suction line, and this connection occurs using a distribution disk, which, by the way, copes with its task quite well.
Once the volume of the working chamber reaches its maximum volume, its connection to the suction line is completely interrupted. If the rotor continues to rotate, this means that the device is operating in the correct mode and the volume of the working chamber should gradually decrease. Next, the working fluid of the system flows out of the system through a side slot and is directed towards the pressure line, where a completely new process takes place.
The force of pressing the plates against the rotor also plays a significant role in this whole process. This indicator is determined using the pressure emanating from the internal mechanism. That is why, most often, such installations as standard have two plates operating at the same effective frequency.
Single acting vane pumps
In this system, the movement of the plates has certain restrictions, which end at the level of the stator, which has cylindrical shape surfaces. The unusual location of the stator in the system allows operation internal elements systems are much more efficient.
In this system, like all others, there is a process of filling the working chamber, which is very similar to what we are used to seeing in normal installations. But, despite this, the working process of this unit is fundamentally different from what we often see in conventional installations.
So before purchasing, you should think carefully about what kind of unit you need, and what is the key purpose of purchasing such equipment. By thinking through all this in advance, you can completely protect yourself from a thoughtless purchase.
Vane Vacuum Pump
A vane vacuum pump is a more modernized version of this unit, which has a large number of advantages that you simply cannot see in the regular version of the pump. The main advantage of such an installation is the ability to operate in ultra-high vacuum conditions, which this moment highly valued in today's market.
Now we will look at the advantages and disadvantages of vane vacuum pumps in order to understand whether it is worth overpaying for work on a vacuum basis.
Advantages of vacuum vane pumps:
- Possibility of ultra-high vacuum formation
- High level of performance
- Wider range of applications
- Ability to run multiple processes simultaneously
Disadvantages of vacuum vane pumps:
- Dimensions are too large and cannot always fit in the right place
- High level of noise and vibration during operation
Having looked at the advantages and disadvantages, we can conclude that vacuum vane pumps still have more advantages, and if you still decide to take a more productive unit, then a vacuum vane pump is easy the best option, which is actually worth paying extra for.
Rotary vane pumps
Rotary vane pumps are now in great demand on the market, and many manufacturers of various products are willing to pay a lot of money to buy such equipment. If we consider the entire range of vane pumps, then you can find both expensive units and more budget ones.
Now we will look at the most good option rotary vane pump, which will be the most practical in terms of price and quality.
The RZ 6 rotary vane pump is a device that manages to combine not only high specifications, and also build quality, stability in operation, low cost and a huge quantity important points, which should always be remembered.
If we talk about the scope of application of rotary vane pumps, we can see that they are used in a wide variety of industries. Now we will look at those areas of industry where at the moment they have become a key element, without which production could not be the same.
Areas of application of rotary vane pumps:
- Radio engineering industry
- Chemical industry
- Oil production
Each of these industries is currently in dire need of rotary vane pumps, which have now become an integral part of work in all these areas.
Oil pumps
If we judge by the type of pumps that have found their greatest application in most industries, then, of course, we can say that these are oil pumps. It is this category of devices that is currently the most popular, since most users are accustomed to trusting proven designs.
Nowadays dry pumps are becoming increasingly popular, but still not everyone is ready to overpay, knowing at the same time that they are buying equipment that has not yet been fully tested. As for oil units, they have long ago managed to establish themselves in the market and prove that they are capable of working in a wide variety of conditions, delivering stable high performance productivity.
At the same time, users are also confident that such equipment, thanks to constant lubrication, is more reliable, and its internal parts will not succumb to wear.
Dry Oil Free Vacuum Pump
A dry oil-free vacuum pump is an air-based device that allows it to minimize the threat of overheating that can occur due to a lack of oil in the system. IN Lately many began to lean towards dry vacuum pumps. The main reason This is achieved through a new operating technology that does not require constant lubrication or the addition of any liquid.
All the user needs to do is turn on the vacuum pump, after which it can work without any interruptions. But still, we should not forget that this is a technique and must be constantly looked after. By following all the necessary procedures for this device, you can be sure that it will serve you for many years and during this time its internal parts will remain in perfect order and will continue to provide the same high performance indicators.
Basic principle of any type of vacuum pump- this is repression. It is the same for all vacuum pumps of any size and any application. In other words, operating principle of a vacuum pump comes down to removing the gas mixture, steam, air from the working chamber. During the displacement process, the pressure changes and 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, pumping out the gas environment from the required space and to do this within a given time. If any of these conditions are not met, then an additional vacuum pump must be connected. So, if the required pressure is not provided, but within the required period of time, a fore-vacuum pump is connected. It further reduces the pressure so that everything is completed the necessary conditions. This operating principle of a vacuum pump is similar to a series connection. Conversely, if the pumping speed is not ensured, but the required vacuum value is achieved, then another pump will be required that will help achieve the required vacuum faster. This principle of operation of a vacuum pump is similar to a parallel connection.
Note. The depth of the vacuum created by a vacuum pump depends on the tightness of the working space created by the pump elements.
To create a good seal in the working space, special oil is used. It seals gaps and completely covers them. A vacuum pump with such a device and operating principle 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, since they do not require maintenance with oil changes and so on.
In addition to industrial vacuum pumps, small pumps that can be used at home are widely used. These include a manual vacuum pump for pumping water from wells, reservoirs, swimming pools and other things. The operating principle of a manual vacuum pump is different, it all depends on its type. There are different types of hand vacuum pumps:
- Piston.
- Rod
- Winged.
- Membrane.
- Deep.
- Hydraulic.
Piston Vacuum Pump it works due to the movement of a piston with valves inside it into the middle of the body. As a result, the pressure decreases and water rises through the bottom valve while the piston handle moves down.
Rod vacuum pump The principle of operation is similar to a piston, only the role of a piston in the body is performed by a very elongated rod.
Vane Vacuum Pump has a completely different operating principle. 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 chamber wall, this increases the pressure and the water splashes out.
More complex design is rotary vacuum pump. But this complexity is compensated 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, using centrifugal force, draw the liquid into the container, and then physical strength pushes her out.
Diaphragm Vacuum Pump has no rubbing parts, so it can be used for pumping very dirty mixtures. Using an internal pendulum and membrane, a vacuum is created, which moves the liquid through the body to the desired location. To prevent the housing from jamming due to accidentally retained 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). Its operating principle is the same as that of a piston, but with a very long rod.
Hydraulic Vacuum Pump pumps viscous substances well, but wide application he didn't receive it. We will consider in more detail the principle of operation and design of vacuum pumps on its individual types.
Operating principle of liquid ring vacuum pumps
One of the types of vacuum pumps is a liquid ring vacuum pump; its operating principle is based on creating a tightness of the working volume using a liquid, namely water.
Let's take a closer look at the liquid ring vacuum pump and its operating principle. Inside the body of the liquid ring pump there is a rotor, which is offset slightly upward relative to the center. Located on the rotor Working wheel with blades that rotate during operation. Water is pumped inside the housing. When the wheel moves, the blades capture water and throw it towards the body by centrifugal force. Since the rotation speed is quite high, the result is the formation of a water ring around the circumference of the housing. In the middle of the body there is free space, 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 is crescent-shaped, and it is divided into cells by the wheel blades. These cells are obtained different sizes. During movement, the gas moves alternately through all cells, heading towards a decrease in volume and at the same time compressing. This happens a large number of times, the gas is compressed to the required value and exits through the discharge hole. When the gas passes through the working chamber, it is cleaned and comes out clean. This property turns out to be very useful for pumping contaminated media or gaseous media saturated with steam. The vacuum pump constantly loses a small amount during operation. working fluid, therefore, the design of the vacuum system includes a reservoir for water, which then, according to the operating principle, is returned 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 a liquid ring vacuum pump works and the principle of its operation 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. The rotor is equipped with blades that can move along these slots under the influence of springs.
Having examined the device, now we will consider the operating principle of rotary vacuum pumps. The gas mixture enters the working chamber through the inlet and moves through the chamber under the influence of the rotating rotor and blades. The working plate, pushed away from the center by a spring, covers the inlet hole, the volume of the working chamber decreases, and the gas begins to compress.
Note. During gas compression, condensation may occur due to steam saturation.
When the compressed gas comes out, the resulting condensate comes out with it. This condensate can adversely affect the operation of the entire pump, so it is still necessary to include a gas ballast device in the design of rotary vane pumps. You can see schematically how a rotary vane vacuum pump works, its operating principle, in the figure below using the Busch R5 pump as an example. As mentioned, a rotary vane pump is an oil pump. Oil is necessary to eliminate all gaps and cracks 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 container. The lighter air mixture passes into the upper chamber of the separator, where it is finally cleared of oil. And the oil, which weighs more, settles in the oil container. From the separator, the oil returns to the inlet.
Note. High-quality pumps clean the air very thoroughly, there is practically no oil loss, so adding oil to such pumps is extremely rare.
Operating principle of the VVN pump
VVN is a water vacuum pump, the operating principle of which is the same as that of a liquid 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 from the engine through the coupling. This provides high rotor speeds, and as a result, the possibility of obtaining a vacuum. True, VVN pumps can only create low vacuum, which is why they are called low-pressure pumps. Simple VVN pumps can pump out gases saturated with vapors and contaminated 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 a reaction with the chemical composition of the gas. Therefore, there are models of VVN pumps, the parts of which are made of titanium alloy or nickel-based alloy. They can pump out mixtures of any composition without fear of damage. The VVN pump, due to its operating principle, is designed only in a horizontal design, and gas enters the chamber from above along the axis.
A turbomolecular pump (TMP) is a special pump that allows you to create and maintain a deep vacuum for a long time, on the order of 10 -2 to 10 -8 Pa. The etymological meaning of the name of the pump is of interest. The prefix “turbo” is a shortened version, introduced into the technical lexicon since 1900, of the term “turbine”. Both of these words come from the French. “turbine” - “turbine”, and earlier from lat. “turbo”, meaning “to cause confusion, disturb, whirlwind, top.” The second part of the first word “molecular” comes from Lat. “molecule” - “part, particle”, as a diminutive of “moles” - “mass, lump, bulk”. The next term “pump” is originally ours, Slavic, as it was transformed from the Old Orthodox words “suck, ssati, ss”, meaning “to suck breast milk", "suck the brain bones", "draw out liquid."
In this article we will look at:
- pfeiffer turbomolecular pump;
- turbomolecular pump agilent tv81m;
- high-vacuum turbomolecular pump twistorr 84 fs;
- turbomolecular pump tg350f;
- power supply unit for turbomolecular pumps type bp 267;
- turbomolecular pump operating 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;
- oil-free vacuum piston pump;
- fore-vacuum pump 2nvr 5dm.
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In 1913, the German scientist Wolfgang Goede 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. A gas vacuum of up to 10 -4 mm was obtained mercury. The new pump even began to be produced by the German company Leybold’s Nachfolgers, but was not widely used. Firstly, there was no urgent need for it, and secondly, technological difficulties with the manufacture of such small gaps interfered. Macroscopic solid particles (pebbles, chips, glass) entering the pump along with the gas led to jamming of the rotor.
In the late 1950s there was renewed interest in molecular pumps
Only at the end of the 50s of the last century was interest in molecular pumps renewed, when the German engineer W. Becker invented the Pfeiffer turbomolecular vacuum pump with a large number bladed disks on the shaft and with increased gaps, about 1 mm. This pump was patented in 1957 by Pfeiffer Vacuum. Further, the design 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 from the Italian company Agilent Technologies, the hybrid turbomolecular pump TG 350F from the Japanese company Osaka Vacuum and others appeared. Moreover, the components of these devices are often interchangeable. For example, a power supply unit for a turbomolecular pump type BP-267 can be used for pumps of models NVT-340, NVT-950, 01AB-450, 01AB-1500.
In a molecular pump, pumping out a gaseous medium is carried out by imparting mechanical impulses of energy to the molecules of the substance from solid, liquid, and gaseous surfaces of the pump moving at high speed.
Moreover, in a molecular pump the direction of movement of the working surfaces and gas molecules coincide, and in a turbomolecular pump the directions of movement of the working elements and molecules are mutually perpendicular. Cross-sectional image of a molecular pump
- Based on their operating principle, molecular pumps are divided into:
- mechanical (rotor and turbine);
- ejector;
- steam jet;
- gas jet;
- water jet;
For example, the high-vacuum molecular pump MDP 5011 is a device with mechanical operating elements. The movement of gas molecules to the pump outlet is ensured by the solid surface of the rotor-glass, which rotates at 27,000 rpm. This model MDP 5011 is the best-selling turbopump. Clearly, you are interested in the price of the MDP5011 molecular pump. Contact us for such questions, call, write to e-mail. We will advise and help.
A turbopump is a pumping device driven by a turbine, the components and parts of which are included in the design of the pump. Distinguish the following types turbopumps depending on the type of pumped working medium.
Appearance turbopumps - Turbopumps for pumping liquids.
- Turbopumps for pumping suspensions.
- Turbopumps for pumping gases.
The disadvantages of turbopumps include the complexity of the design, long downtime when repairing the pump or turbine, and high cost. Therefore, if you need to buy an oil turbopump TMN-6/20, the question naturally arises, what is the price of the turbopump. If you are not satisfied with it in other companies, come to us.
Turbomolecular pumps (TMP) are designed as multistage 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 are made, placed mirror to each other, makes it possible to effectively pump out gas molecules due to the different probability of molecules passing through the channels located at an angle in the pumping and supply directions. TMN are fixed on massive base
through shock absorbers, which reduces vibration during pumping. Appearance of the turbomolecular vacuum pump TMN-500 The operating principle of a 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 split second and fly off tangentially to the rotating turbine. The kinetic energy of the blades is summed up with the thermal energy of the moving gas particles. The chaotic movement of molecules turns into accelerated movement in a given direction of pumping. This effective action
Domestic double-flow oil-free pumps make a good impression: the TMN-500 turbomolecular vacuum pump and the TMN-200 pump with a capacity of 500 and 200 l/sec, respectively. Of course, in terms of build quality and design they are inferior to their foreign counterparts. But at a low cost, they are characterized by operational reliability, reliability and sufficient durability.
A dry (oil-free) vacuum pump works in the same way as an oil-based one. But a dry-type pump does not use oil to lubricate rubbing parts, and there are no sealing devices. Therefore, the material used for the blades of dry pumps is not metal, but a graphite composite material. Graphite blades are cheaper than metal blades made of titanium, aluminum, of stainless steel
, are characterized by a low friction coefficient and reliably seal the pump chamber. Appearance of a dry vacuum pump
- Advantages of oil-free vacuum pump: absence of oil vapor when air leaves the pump, workplace
- becomes clean, the environment improves;
- no need to purchase and fill expensive oil, monitor its level and contamination;
lower cost.
- Disadvantages of a dry pump:
- the depth of the vacuum created is lower than that of oil-sealed pumps;
- the durability of graphite blades is significantly less than that of metal blades;
wear products in the form of dusty graphite enter the atmosphere.
However, experts believe that oil-free vacuum pumps are the future. And now they are already trying to buy an oil-free rotary vane vacuum pump, an oil-free piston vacuum pump, an oil-free fore-vacuum pump, without paying attention to their price. Since the simpler and cheaper operation of a dry pump will pay for all the initial costs.
A fore-vacuum pump is a device for creating the initial vacuum of a gaseous medium - a fore-vacuum (from the German “vor” - “in front of, in front” of the vacuum and the Latin “vacuus” - “empty”).
The principle of operation is that the foreline pump is installed as the first stage in a system of pumps that create high and ultra-high vacuum. Provides energy savings and improves the ability to operate the next high stage pump. If you are interested in the described turbomolecular and forevacuum pumps from our company’s product range, you can obtain more detailed information from our consultants. Our highly qualified specialists will help you choose optimal option pumps, explain the terms of purchase, operation and service, and justify prices. They will assist you in selecting spare parts and auxiliary materials, such as blades for Becker oil-free pumps, oil for a fore-vacuum pump and others. Call our phones or contact us by E-mail. We will be happy to help you.
Extremely reliable and efficient dry, claw and screw type vacuum 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 production of dry vacuum pumps is the English company Edwards. Edwards is a pioneer in the field of dry gas pumping. More than 90 years of experience in the application of vacuum pumps in different conditions applications, including processes with high dust and contaminant content, and more than 150,000 dry vacuum pumps delivered worldwide, provide the most sophisticated solution for dry vacuum applications.
Dry pumping technology provides significant reductions in operating costs, increased productivity, improved product quality, and the creation of more favorable conditions labor in work areas. This technology guarantees high levels reliability in situations where oil sealed pumps are at the edge of their operating range. “Dry” pumps are capable of pumping out media with the highest permissible water vapor pressure at the pump inlet, several times higher than the highest water vapor pressure for pumps with an oil seal, and they do this in the complete 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, the Drystar claw-type dry vacuum technology was an innovation in the world of vacuum and continues to enjoy well-deserved popularity around the world to this day.
Thus, the first models of pumps from the Edwards company, with a claw mechanism, trademark Drystar GV series pumps are now installed all over the world in a wide range of general industrial processes, metallurgy, drying, surface treatment and semiconductor manufacturing. The principle of operation of GV pumps is based on a claw gripping mechanism, and the additional Roots stage used in the design of the pumps allows increasing pumping speed in the operating range and achieving maximum operating speed.
The experience gained during the development of dry claw pumps was used in the EDP series pumps, the main difference of which from the GV series pumps is the vertical direction of the flow of the pumped medium, due to which, if liquids enter the working volume, they immediately flow out of the pump without affecting it. Wherein heat, maintained inside the pump, avoids condensation of media, including chemically active ones, and, as a result, the influence of corrosion. Thanks to this feature, the EDP series pumps optimally meet high demands. technological processes chemical and pharmaceutical industries.
In parallel with the technology of dry pumping with a claw gripping mechanism, the technology of vacuuming with screw pump rotors was being developed.
The IDX series progressive cavity pumps are ideal for processes requiring high performance when working on a vacuum or quickly pumping out atmospheric pressure. The pumps use a unique two-way symmetrical screw mechanism, which simplifies the system for compensating for thermal expansion of the shafts. This design, which has no analogues in products from other manufacturers, allows you to easily pump gas media with a high dust content. It is important to note that the pump can be used as a foreline pump in a multi-stage vacuum system. Systems based on IDX pumps are a standard solution in steel evacuation processes.
Subsequently, by analogy with the advent of “chemical” versions of 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 used in chemical and petrochemical production conditions.
In combination with booster pumps EH/HV/SN, dry vacuum pumps of the GV, EDP, IDX series can achieve a capacity of up to 120,000 m 3 /h. As a special case, IDX-based systems for metallurgy, which are ready-made solutions for ladle-furnace systems of 50, 100 and 150 tons (vacuum degassing VD and vacuum decarburization VOD processes). Pumping speed can be varied by adding additional stages, allowing vacuum systems to be designed to meet the needs of a specific process.
Currently, a new generation of vacuum pumps for general industrial processes - the GXS screw type pump - has become actively widespread. This pump is a completely ready-to-use solution, the pump is ready for use immediately after delivery. It is equipped with a control panel located directly on the body, and also has a number of additional options, allowing you to configure a system that fully meets the needs of a specific customer. The wide range of GXS pumps can be presented either in the form factor of a single-stage pump or in combination with a booster pump (in a single housing), which allows for performance from 160 to 3,500 m 3 /h.
Currently, Edwards remains closely focused on vacuum processes in the chemical and pharmaceutical industries. Thus, based on the GXS, the CXS series pumps were developed. The main difference between this pump and the GXS is that all elements of the pump’s electronic control system are placed in a separate explosion-proof unit.
You can find out more about the capabilities and characteristics of Edwards dry vacuum pumps in the relevant sections of our catalog.
Innovative development of the manufacturer Edwards - EDS series pumps for complex technological processes in the chemical, petrochemical and pharmaceutical industries
Vacuum pumps are widely used in a wide variety of industries and science. The main application of vacuum pumps is to remove air or gas from a hermetically sealed volume and create a vacuum in it. We will look at the most common types, characteristics of vacuum pumps, their operating principles and main applications.
Vacuum pumps are classified according to their operating pressure range into:
- primary (forevacuum) pumps,
- booster pumps
- secondary pumps.
In each pressure range apply Various types vacuum pumps that differ from each other in design. Each of these types has its own advantage in one of the following areas: possible pressure range, performance, price and frequency and ease of maintenance.
Regardless of the design of vacuum pumps, the basic operating principle is the same. The vacuum pump removes molecules of air and other gases from the vacuum chamber (or from the outlet of a higher pressure vacuum pump, if connected in series).
As the pressure in the chamber decreases, subsequent removal of additional molecules becomes exponentially more difficult. Therefore, industrial vacuum systems must cover a wide range of pressures from 1 torr. In the scientific field, this figure reaches torr or lower.
The following pressure ranges are distinguished:
- Low vacuum: >atmospheric pressure to 1 torr
- Medium vacuum: 1 torr to 10-3 torr
- High vacuum: 10-3 torr to 10-7 torr
- Ultra-high vacuum: 10-7 torr to 10-11 torr
- Extreme high vacuum:< 10-11 торр
Correspondence of vacuum pumps to pressure ranges:
Primary (forevacuum) pumps - low vacuum.
Booster pumps - low vacuum.
Secondary (high vacuum) pumps: High, ultra-high and extremely high vacuum.
Classification of vacuum pumps according to the principle of working with gas
There are two main technologies for working with gas in vacuum pumps:
- Gas pumping
- Gas capture
Pumps operating using gas pumping technology are divided into kinetic pumps and positive displacement pumps. 
Kinetic pumps operate on the principle of transferring momentum to gas molecules from high-speed blades to ensure constant movement of gas from the pump inlet to the outlet. Kinetic pumps typically do not have sealed vacuum chambers, but can achieve high compression ratios at low pressures.
Positive displacement pumps operate by mechanically capturing a volume of gas and moving it through the pump. In a sealed chamber, gas is compressed to a smaller volume at more high blood pressure and after that, the compressed gas is forced into the atmosphere (or into the next pump).
Typically kinetic and volumetric operate in series to provide higher vacuum and flow. For example, very often a turbomolecular (kinetic) pump is supplied assembled in series with a screw (displacement) pump into a single unit.
Pumps using gas capture technology capture gas molecules on surfaces in a vacuum system. These pumps operate at lower flow rates than transfer pumps, but can still produce ultra-high torr, oil-free vacuums. Entrainment pumps operate using cryogenic condensation, ion reaction, or chemical reaction and have no moving parts.
Types of vacuum pumps depending on design
Depending on their design, vacuum pumps can be divided into oil (wet) and dry (oil-free), depending on whether the gas is exposed to oil or water during the pumping process.
The wet pump design uses oil or water for lubrication and/or sealing. This liquid may contaminate the pumped gas. Dry pumps do not have liquid in the flow part and depend on sealed gaps between the rotating and static parts of the pump. The seal most often used is a polymer (PTFE) or a diaphragm to separate the pump mechanism from the pumped gas. Dry pumps reduce the risk of oil system contamination compared to wet pumps.
The following designs are most often used as primary (fore-vacuum) pumps, described below.
Primary foreline pump. Principle of operation. Design options
Oil Filled Rotary Vane Pump
(wet, volumetric)
In a rotary vane pump, gas enters the inlet and is captured by an eccentrically mounted rotor, which compresses the gas and transfers it to the outlet valve. The spring-loaded valve allows the gas to be released when atmospheric pressure is exceeded. Oil is used to seal and cool the blades. The pressure achieved by a rotary pump is determined by the number of stages. The two-stage design can provide a pressure of 1 × 10-3 mbar. Productivity ranges from 0.7 to 275 m3/h.
Water ring vacuum pump. Design and operating principle
(wet, volumetric)
A liquid ring pump compresses gas using a rotating impeller located eccentrically inside the pump housing. The liquid is supplied to the pump and, through centrifugal acceleration, forms a moving cylindrical ring. This ring creates a series of seals in the spaces between the impeller blades, which are the compression chambers. The eccentricity between the axis of rotation of the impeller and the pump casing leads to a decrease in the volume between the impeller blades and thereby to compression of the gas and its release through the outlet pipe. This pump has a simple, robust construction, since the shaft and impeller are the only moving parts. The liquid ring pump has a large power range and can provide a pressure of 30 mbar when using water at a temperature of 15 ° C. When using other liquids, more is possible low pressure. The range of available capacities is from 25 to 30,000 m3/h.
Diaphragm Vacuum Pump
(dry volume)
Diaphragm pumps use a flexible diaphragm that is connected to a rod and moves alternately in opposite directions so that gas enters the space above the diaphragm and completely fills it. The intake valve then closes and the exhaust valve opens to release the gas.
The diaphragm vacuum pump is compact and very easy to service. Diaphragms and valves typically last more than 10,000 operating hours. The diaphragm pump is used to support small turbomolecular pumps in clean, high vacuum. This is a pump low power, widely used in research laboratories for sample preparation. Typical ultimate pressure is 5 x 10-3 mbar. Capacity from 0.6 to 10 m3/h (0.35 to 5.9 ft3/min).
Scroll Vacuum Pump
(dry volume)
The main elements of the pump are the spiral rotor and stator. The expanded gas enters large circular spaces that narrow when it reaches the center of the spiral rotating rotor. The PTFE polymer seal provides a tight seal between the pump volutes without the use of oil in the pumped gas. Achievable pressure 1 × mbar. Capacity from 5 to 46 m3/h.
Booster pumps
Double Rotor Vacuum Pump
(dry volume)
Double rotor pumps are primarily used as booster pumps and are designed to remove large volumes of gas. The two rotors rotate without touching each other to continuously transfer gas in one direction through the pump. This improves the performance of the primary/foreline pump, increasing pumping speed by approximately 7:1 and improving final pressure, approximately 10:1. Booster pumps can have two or more rotors. Typical Ultimate Pressure<10-3 Торр может быть достигнуто (в сочетании с первичными насосами). Производительность составляет подобных агрегатов может достигать около 100 000 м3/ч.
Cam-gear pump
(dry volume)
A cam-gear pump has two cams that rotate in opposite directions. The operating pattern of a vacuum pump is similar to a rotary pump, except that the gas is transferred in an axial direction rather than from top to bottom. Very often, lobe and two-rotor pumps are used in combination. The rotor stages and cam stages are mounted on one common shaft. This type of pump is designed for harsh industrial environments and provides high performance. Typical limit pressure is 1 x 10-3 mbar. Productivity ranges from 100 to 800 m3/h.
Screw pump
(dry volume)
The main working parts of the unit are two rotating screws that do not touch each other. Rotation transfers gas from one end to the other. The screws are designed in such a way that as gas passes through them, the space between them becomes smaller and the gas is compressed, thereby causing a reduced inlet pressure. This pump has high performance. The screw pump can handle media containing liquid and impurities, and also performs well under harsh conditions. Typical ultimate pressure is about 1 × 10-2 Torr. Productivity can reach 750 m3/h. 
Secondary (high vacuum) pumps
Turbomolecular pump
(dry, kinetic)
Turbomolecular pumps work by transferring kinetic energy into gas molecules using high-speed rotating angled blades that propel the gas at high speeds. The rotation speed of the blade tip is usually 250-300 m/s. Receiving an impulse from the rotating blades, gas molecules move towards the outlet. Turbomolecular pumps provide low pressure and have low performance parameters. Typical ultimate pressure is 7.5 x 10-11 Torr. Performance range from 50 to 5000 l/s. Pump stages are often combined with deceleration stages, allowing turbomoleculars to reach higher pressures (> 1 Torr).
Diffusion steam-oil pumps
(wet, kinetic)
Steam diffusion pumps transfer kinetic energy to gas molecules using a high-speed heated oil stream that moves the gas from the inlet to the outlet. This ensures reduced inlet pressure. This design is quite outdated. To a large extent, they are being replaced on the market by more convenient dry turbomolecular pumps. Oil diffusion pumps have no moving parts and provide high reliability. This vacuum pump has a low price. Ultimate pressure less than 7.5 x 10-11 Torr. Performance range 10 - 50,000 l/s.
Cryogenic pump
(dry, gas capture technology)
Cryogenic pumps work by capturing and storing gases and vapors rather than pumping them through themselves. This type of pump uses cryogenic technology to freeze or trap gas on a very cold surface (cryocondensation or absorption) at a temperature of 10°K to 20°K (minus 260°C). These pumps are very efficient but have limited gas storage capacity. The collected gases/vapors must be periodically removed from the pump, heating the surface. They are pumped out using another vacuum pump. This process is also known as regeneration. Cryogenic pumps require the installation of an additional compressor cooling system to create cold surfaces. These pumps can reach pressures of 7.5 x 10-10 Torr and have a capacity range from 1200 to 4200 l/s.
Major manufacturers of vacuum pumps
You can buy a vacuum pump from the following manufacturers:
BUSCH www.buschvacuum.com
Becker www.beckerpumps.com
Elmo Rietschle http://www.gd-elmorietschle.com/en
NASH http://www.gdnash.com/liquid_ring_vacuum_pumps/
Robuschi http://www.gardnerdenver.com/en/robuschi/products/vacuum-pumps
Pfeiffer Group group.pfeiffer-vacuum.com
Samson Pumps www.samson-pumps.com
