Vacuum pump rotary dry type. The principle of operation of vacuum pumps of various types, their features. Ion 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 the required space and to do this within a 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. The depth of the vacuum created by the 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:

Piston.
Rod.
winged.
Membrane.
Deep.
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 there is an impeller with blades rotating during operation. Water is pumped inside the body. When the wheel moves, the blades capture water and centrifugal force throw it towards the hull. 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 come in different sizes. During the movement, the gas moves alternately through all cells, heading towards a decrease in volume and simultaneously compressing. This happens a large number of times, the gas is compressed to the required size and exits through the injection hole. When the gas passes through the working chamber, it is purified and comes out clean. This property is very useful for pumping contaminated media or steam-laden gaseous media. 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. 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 to the 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 saturated with vapors, polluted media, 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 chemical compositions 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.

Catalog section on screw dry vacuum pumps DRYVAC from Leybold GmbH (Germany)

Screw vacuum pump DRYVAC from Leybold GmbH (Germany)

The principle of operation, based on the rotation of the screws, allows the extraction of gas without the presence of oil in the compression area. The DRYVAC screw vacuum pump has a compression cavity formed by the surface of the housing, as well as two rotors that perform synchronous rotation. Due to the fact that the rotors rotate in opposite directions, there is a gradual movement of the compression cavity from the suction side towards the exhaust side, which ultimately provides the desired pumping effect.

Despite the fact that in the considered design, the process of internal gas compression occurs, the “particle path” in the internal space of the pump is minimal. This feature greatly simplifies maintenance, and also reduces the need for service work to a possible minimum.

The DRYVAC range is a new series of oil-free devices based on screw vacuum pumps. The complete set, which can be different, must be selected taking into account the scope of application, as well as other individual criteria.

When developing the series, the actual needs of processes were taken into account, in which the requirements for vacuum pumping systems are quite high. The considered devices are used, in particular, in the manufacture of screens, photovoltaic elements, as well as for a number of other industrial applications.

Each pump version of the DRYVAC range is water-cooled, thanks to which it is characterized by a compact design and the ability to be relatively easy to install even in complex systems in parallel with the reliable RUVAC pumping units of the WH, WS and WA series.

The DRYVAC screw vacuum pump range includes:

model DV 450
model DV 450S
model DV 650
model DV 650-r
model DV 650 S
model DV 650 S-i
model DV 650 C
model DV 650 C-r
model DV 1200
model DV 1200 S-i
model DV 5000 C-i

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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 work on the basis of key assemblies consisting of plates and a rotor.

The plates inside the system move exclusively in the radial direction, since only in this way it is possible to achieve the desired level of performance. If we talk about the differences between the two categories of vane pumps, then they are only in the very shape of the stator surface, which differs slightly 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 work as evenly as possible. This is achieved due to the fact that all the plates inside the system have time to complete two cycles at once in 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 power surges can occur, which are handled very well by special sensors that regulate all such issues.

As for the inner plates, they are constantly under pressure and pressed against the inside of the working stator. It is this density that allows you to achieve the most high level tightness, which is also very important for the quality of the system.

But this is far from the limit, so the rotation of the stator is only the beginning, after which a similar procedure will be done 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 is made using a distribution disk, which, by the way, does its job quite well.

After 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 correct mode and the volume of the working chamber should gradually decrease. Further, the working fluid of the system flows out of the system through the side slot and is directed towards the pressure line, where a completely new process takes place.

A significant role in this whole process is played by the force of pressing the plates to the rotor. This indicator is determined using the pressure emanating from the internal mechanism. That is why, most often, such installations in standard equipment have two plates operating at the same effective frequency.

Single acting vane pumps

In this system, the movement of the plates has certain limitations, which end at the level of the stator, which has a cylindrical surface. The unusual location of the stator in the system allows the internal elements of the system to work much more efficiently.

In this system, as well as in all others, there is a process of filling the working chamber, which is very similar to what we are used to seeing in conventional installations. But, despite this, the very working process of this unit is fundamentally different from what we often see in conventional installations.

So before buying it is worth considering what kind of unit you need, and what is the key purpose of buying such equipment. Thinking through all this in advance, you can completely protect yourself from a rash purchase.

Vane vacuum pump

The vane vacuum pump is a more modernized version of this unit, which has a large number of advantages that you simply cannot see in regular version pump. The main advantage of such an installation is the possibility of its operation in ultra-high vacuum conditions, which is currently very much appreciated in the modern market.

Now we will look at the advantages and disadvantages of vane vacuum pumps in order to still understand whether it is worth overpaying for work on a vacuum basis.

Advantages of vacuum vane pumps:

Possibility of formation of ultrahigh vacuum
High performance
Wider range of applications
Ability to run multiple processes at the same time

Disadvantages of vacuum vane pumps:

Too large dimensions that can not always fit in the right place
High noise and vibration levels during operation

After reviewing 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 just the best option which is actually worth paying more 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 installations and more budget ones in it.

We will now 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 has managed to combine not only high specifications, but also the build quality, stability in operation, low cost and a huge amount of important points which should always be remembered.

If we talk about the scope of rotary vane pumps, we can see that they are used in a variety of industries. Now we will consider those industries where they have become key element, without which production could not be the same.

Scope of application of rotary vane pumps:

Radio engineering industry
Chemical industry
Oil production

Each of these industries is currently in dire need of the work of rotary vane pumps, which have now become an integral part of the work in all these areas.

Oil pumps

Judging by the type of pumps that have found their greatest use 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, as most users are used to trusting proven designs.

Now dry pumps are gaining more and more popularity, but still, not everyone is ready to overpay, while knowing that they are buying equipment that has not yet been fully tested. As for oil installations, they have already managed to establish themselves in the market a long time ago and prove that they are able to work in the most different conditions delivering consistently high performance.

At the same time, users are also confident that such equipment, due to constant lubrication, is more reliable, and its internal parts will not give in to wear.

Dry Oil Free Vacuum Pump

The dry oil-free vacuum pump is an air-based device that allows it to minimize the risk of overheating that can occur due to lack of oil in the system. Recently, many have begun to lean towards dry vacuum pumps. main reason This is due to the new technology of operation, which does not require constant lubrication or the addition of any liquid.

All that is required from the user is to turn on the vacuum pump, after which it will be able to work without any interruption. But still, do not forget that this is a technique and you need to constantly look after it. By doing 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 still give the same high performance.

Turbomolecular pump (TMP) refers to special pumps that allow you to create and long time maintain a deep vacuum, of 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. The rarefaction of the gas up to 10 -4 mm Hg was obtained. 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. 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.

Cutaway image of a molecular pump

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 such as call or email. 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. There are the following types of 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 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.

Appearance of the turbomolecular vacuum pump ТМН-500

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. The chaotic movement of molecules turns into accelerated movement in a given direction of pumping. Such effective action rotor is possible only in the mode of molecular gas flow, 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.

Appearance of dry vacuum pump

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.

Appearance of the foreline pump 2NVR-5DM

If you are interested in the described turbomolecular and backing pumps from the range of our company, you can get more detailed information from the 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 an apparatus has a device similar to a double-acting reciprocating compressor. 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. The ingress of the oncoming gas flow into the inlet 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 operation of such a pumping unit is based on the fact that the gas moves as a result of the mechanical movement of the 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 operate without lubricant and with lubricant.

This type of pumping units is used in a wide variety of industries: chemistry, metallurgy, electronics, food industry, medicine, cosmonautics. Mechanical vacuum pumps are also used as part of a wide variety of industrial installations, as well as in technical processes (for example, remelting of metals, deposition of thin films, simulation 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 the useful action. 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 residual 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 is running continuously, then the volume of sucked gas is equal to the volume emitted into the atmosphere process gases and the volumes that are sucked in from the outside through loose areas do not change in 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.