What is an air compressor for? The use of reciprocating compressors in modern enterprises. Advantages of oil aggregates

We learned what a compressor is thanks to the invention of a pump with a piston, which became the prototype of a modern device. The compressor was invented by the German physicist Otto von Guericke, who lived in the 17th century. In the 18th and 19th centuries, the prototype of the modern power pressurizing machine contributed to the development of metallurgy and mining.

The main task of the then called blowers in metallurgy was to supply air to blast furnaces, later open-hearth furnaces or converters in order to ensure a complete combustion process.

Now, what is a compressor - a device that creates a pressure at the outlet above atmospheric.

Types of compressors according to the principle of operation

According to the principle of operation or a feature of the pressure increase process, the types of compressors depend on the design of the device and are divided into two large groups: volumetric and dynamic.

• The workflow of the volumetric principle of operation is carried out as a result of a change in the volume of the chamber and is divided into piston, screw, rotary-gear, membrane, rolling rotor, liquid-annular, spiral, etc.
• The principle of dynamic action is the interaction of rotating blades with the supplied gas, and are divided into centrifugal and axial.

It is interesting to use the type of compressors in internal combustion engines, where they have already become a component of aircraft. Aircraft are known to fly at high altitudes, where much less oxygen is available for combustion. The introduction of power-driven pressurization machines as air blowers allowed aircraft to fly at high altitude without reducing engine power.

Similar devices on some modern cars work on the same principle. They receive energy directly from the engine shaft and contribute to the supply of fuel to the combustion chamber to increase power.

It is clear that in order to increase the power of a car engine, it is necessary either to increase the volume of the combustion chamber, or the amount of fuel burned. Increasing the volume of the combustion chamber and the engine as a whole is not always advisable. It is easier to increase the amount of fuel, however, a certain amount of oxygen is needed to burn the fuel, which is not enough at normal pressure. And here the type of compressor comes to the rescue, which, by compressing, introduces under pressure a larger amount of air with oxygen and, thus, the engine power increases dramatically.

Various types of compressors will be used in various types of installations: chemical, refrigeration, energy, car repair shops, for pneumatic tools, installations for dental offices, general and home use, for example, when brewing coffee even in a coffee machine.

Equipment for the production of food products and packaging also needs this type of device.
Such power machines are used to increase pressure at industrial enterprises, ranging from powerful automatic booster compressors, stations consisting of many low and high pressure units, systems for dehumidifying, purifying and cooling air, having a single control and monitoring to automatic blowing units with low pressure devices. pressure.

Rarely what enterprise does without use of compressed air. At some enterprises it is used for coating various surfaces, at others it is used to ensure the operation of stamping equipment. A compressor is used to produce compressed air.

Purpose and principle of operation

What is a compressor? The official definition is as follows - a device designed to compress gases and pump them to consumers is called an air compressor. How does he work? The principle of operation of the device is quite simple, atmospheric air enters the mechanism that compresses it. Various methods can be used for this, which will be discussed below. The mechanism that compresses the air determines the design and principles of operation of the compressor. For efficient operation of the equipment, it must be connected to an electrical network and an air network through which compressed air will be transmitted. The motor connection diagram is usually indicated in the operating instructions.

Types of compressors

In the industrial equipment market, there are many offers for the supply of these devices. It can be divided into those used in industry and those used in everyday life, for example, for inflating car wheels. All these devices can work from different types of drive. The electric air compressor 220 V, as the name implies, works from an electric power unit with a voltage of 220 V. But, there are also devices that operate on a voltage of 380 V.

Diesel compressor, powered by an internal combustion engine running on diesel fuel. The use of such equipment is quite popular among builders, it is used when it is not possible to connect electric installations. Diesel-fuelled units enable operation at remote construction sites.

Atmospheric air is supplied to the cylinder head, in which the pistons are installed. The power plant, in turn, transmits torque to the shaft, which ensures the movement of the pistons in the cylinder. It is there that the air is compressed to the required parameters. After compression, it is sent to the air system of the enterprise. Piston compressors are divided into oil and oil-free. Oil is different in that for its efficient operation, special oil is poured into it, which reduces the friction force between the rubbing parts and nodes of the device. This increases its operational resource.

There are many ways to transfer torque from a motor to an actuator. In the manufacture of compressors, couplings or belt drives are most often used. The device on which the latter type is installed is called a belt compressor.

The listed types of equipment are used in almost all industries, they differ from each other in productivity, size and a number of other parameters. But, of course, the main characteristic is the amount of pressure that the compressor can create.

This is a rather complex device, its design includes oil scraper rings, filters for cleaning oil and air, control automation, and this determines that qualified personnel and special tools and devices are required to maintain this device in working condition.

Diaphragm Compressor

The gas is compressed in such a device under the action of a membrane that performs a reciprocating motion. The membrane is driven by a rod, which is fixed on the crankshaft.

The membrane plate is fixed to the working chamber and thus there is no need to use additional parts, such as piston rings, sealing devices, etc.

The membrane type air compressor has the following parameters:

• tightness;
• resistance to corrosion;
• high level of compression;
• reliability design;
• safe operation and easy maintenance.

The membrane-type belt-driven compressor is characterized in that the working medium comes into contact only with the membrane and the internal cavities of the chamber. However, it does not come into contact with the atmosphere. Such a device is used for pumping harmful and toxic substances.

Another advantage of the membrane product is that it does not need to be lubricated, which reduces the risk of contamination of the transported working medium.

Positive displacement compressors

A device in which the process of obtaining compressed air occurs by reducing its volume is called a volumetric compressor. These include the following types of equipment:

• oil-free screw compressors;
• diesel piston compressors;
• household air compressors.

Screw compressors

The history of this equipment began in 1934. Screw compressors are distinguished by high reliability, small dimensions, low metal consumption, which have led to a high consumer demand for equipment of this class. The use of this equipment can reduce the cost of electricity up to 30%. Installations of this type are installed on mobile compressor stations, ship and other refrigeration units.

As a working body, screw rotors are used, on which cavities are applied. They are installed in a housing that can be disassembled in several planes. It has holes and grooves for installation and bearings. In addition, air intake and discharge chambers are formed in the housing. Pumps of this type differ in performance.

These products can develop pressure from 8 to 13 atm., while the air flow can be from 220 to 12400 liters per minute.

Quite often, one unit of such equipment can replace several units of compressors installed in production shops.

When installing and putting into commercial operation of such compressors, it is advisable to install a device at the inlet to clean the air from excess moisture. Some manufacturers complete their products with such filters.

Rotary vane compressors

Compressors of this class operate on the same as piston compressors, that is, on displacement. Energy transfer takes place during compression. The working medium during suction enters the working chamber, its volume decreases when the rotor moves. This compression leads to an increase in pressure and the escape of compressed air through the nozzle.

Compressors of this type can create pressures up to 0.3 MPa, are called blowers, and those that deliver higher pressures are called compressors.

Devices of this type are distinguished by the following advantages:

A more stable, balanced stroke ensures the absence of reciprocating motion. The design of this equipment provides for the possibility of direct connection to the electric power unit. The weight of a rotary compressor will be lower than a reciprocating compressor with similar characteristics. The design does not provide for the use of valves. That is, the number of parts rubbing against each other is reduced.

Dynamic compressors

Compressors of this group are divided into two types - centrifugal and axial. In the first, air is thrown to the outer part of the impeller under the influence of centrifugal force. Thus, a rarefied space is formed on the suction side. The gas constantly enters the working chamber, after passing through the wheel, the air is sent to the diffuser (flow rate damping device), where, in fact, its pressure rises.

For axial-type equipment, air moves along the rotor, and compression is carried out as a result of a change in the speed of its movement between the rotor blades and the guide device.

These compressors can be classified according to the following properties:

1. The outlet pressure, those that provide pressure within 0.015 MPa, are called fans or blowers.
2. By the number of compression stages.
3. As the air moves. If it moves along the axis of the rotor, then it is centrifugal, if across, then axial. There are devices where the air moves diagonally.
4. By type of drive - it can be electric, steam or gas turbine.

Rotary compressors are used in aircraft engines. With its help, air is forced into the combustion chamber.

Compressor performance

This term refers to the volume of gas that is injected in a certain unit of time. The productivity unit is m 3 per minute. This parameter can be specified either at the input or at the output, of course, these will be different numbers. The thing is that when the pressure changes, the volume changes. This characteristic indicates performance at a working environment temperature of 20 degrees Celsius.

Depending on the value of this characteristic, the following groups are distinguished - high productivity (over 100 cubic meters of air per minute), medium (up to 100 cubic meters of air per minute) and small up to (10 cubic meters).

Dynamic devices have some advantages over piston ones. They are simple in design and operation. They have small overall dimensions and weight parameters. Smooth air supply and they do not require additional lubrication. Their installation does not require the manufacture of massive foundations. But, along with this, their efficiency is somewhat lower than that of piston ones.

These compressors have found their application in many industries. For example, in the chemical and oil and gas industries, in metallurgy, mining and many other industries. One of the varieties of dynamic compressors - turbocompressor, installed in gas pipelines.

For many years of operation of such equipment, many devices with different characteristics have been designed and put into operation, in particular, modern machines are capable of providing productivity up to 200 m 3 per minute, with a wheel rotation speed of 250 revolutions per second. And all this with small dimensions and weight parameters.

Aggregation of compressors

The process of mounting the compressor and power plant on the frame is called aggregation. Due to the fact that piston-type devices have vibration, it is necessary to design and manufacture the foundation taking into account these characteristics.

Feature of oil-free appliances

These devices have found their application where it is necessary to ensure high requirements for air purity. They are installed in medical institutions, pharmaceutical and chemical industries. In fairness, it must be said that these devices are among the most affordable devices in terms of their cost. These compressors are easy to operate and maintain. This suggests that there is no need for trained personnel, and there are no special requirements when installing them at the workplace.

But oil-free compressors have some drawbacks, such as excessive noise that occurs during operation. But, manufacturers were able to solve this problem by installing soundproof casings on these products.

When choosing an oil-free compressor, it is necessary to pay attention to the power of the device, their performance and operating pressure parameters, which are shown by the devices installed on the compressor. We must not forget about the volume of the receiver. As a rule, containers with a volume of 50 liters are installed in the compressor device.

Advantages of oil aggregates

The most common method of reducing friction that occurs during the operation of various parts and assemblies is their lubrication. This reduces the load on the product as a whole, in particular, on its key part - the engine.

To solve this problem, special compressor oils are used, which can be used in various operating conditions.

Compressors of this type are cheaper to manufacture. Therefore, the cost of such equipment is significantly cheaper than oil-free counterparts. But in operation, they are more expensive. This is due to the fact that during operation, along with the removal of air from the working area, oil is released. By the way, it must be replaced every 2,000-3,000 hours of operation.

Since there are oil microparticles in the compressed air, oil trapping elements, such as filters, must be installed in the system. After a certain amount of time, they also need to be replaced, and this complicates maintenance, and requires additional costs for the purchase of replacement filters.

However, despite the measures taken, it is not possible to completely clean the air that has passed through the oil compressor. For example, after air treatment on a screw device, its pollution is 3 mg per cubic meter. The purity of the air after it has been processed on a reciprocating compressor directly depends on the level of wear of its parts and assemblies.

This has led to the fact that in certain technological processes the use of oil compressors is prohibited.

Operation features

The regular operation of the compressor primarily depends on the operation of all its components and parts. In particular, intake and exhaust valves. Inside the compressor, where air is distributed, a certain number of spools, distributors and valves are installed. The following types of valves are installed in compressors - poppet, reed, spindle, etc.

In order for the equipment not to reduce power indicators and not consume excess power, the valves that are installed in the compressor must be ground in and must not let air through. When they develop valves, they must be urgently replaced. Increased air consumption can sooner or later lead to a reduction in the life of the equipment.

The delay in valve operation leads to the appearance of knocks, a knock indicates that the seat is wearing out. In addition, a knock may indicate that the upper part of it has been pinched in the case.

The noiselessness of the compressor is a kind of indicator of the quality of the setting and, accordingly, the operation of the device as a whole.

Safety regulations

At construction sites and production, compressor units of various operating principles and purposes are widely used. Compressors can be permanently installed on concrete foundations or mobile, i.e. mounted on a chassis.

Regular use of compressor equipment is permissible subject to a number of conditions:

1. The compressor must be equipped with devices operating in automatic mode, which prevent the permissible operating limit from being exceeded.
2. An unloading valve is provided for quick release of excess pressure.
3. This equipment must be installed at the inlet and outlet, filtration devices that ensure the purity of the air sent for processing to the compressor and create an obstacle to its entry into the room.
4. The presence of installed pressure gauges provide control over the pressure parameters created by the compressor.
5. An oil separator filter must be installed between the compressor unit and the receiver.
6. In addition, air containing toxic or harmful substances must not be supplied to the compressor stop.

Behind the installed equipment, appropriate supervision and maintenance must be established. At the same time, it must be remembered that maintenance and routine maintenance should be carried out by trained personnel. The equipment that is under the supplier's warranty must be serviced by specialists from the appropriate service centers.

In particular, when washing compressor components and parts, only those liquids and compositions recommended by the manufacturer of this equipment should be used. Storage tanks, compressed air must be equipped with safety valves, a drain cock, a pressure gauge. In accordance with the requirements of operational documentation, these tanks (receivers) must undergo routine maintenance and testing. Their results should be recorded in the maintenance log.

When organizing the operation of compressor and related equipment, it is necessary to use the guidelines and other regulatory documents promulgated by control bodies, for example, Rostekhnadzor.

Criteria for selecting compressor equipment

What should be guided by the consumer when choosing an air compressor. Most importantly, he must understand for what purposes the purchased equipment will be used. It must be noted right away that there are separate industries, and only compressors operating without oil can be used in technological operations.

The key parameters of compressor equipment are:

1. Air consumption (performance).
2. Operating pressure.
3. air cleanliness requirements.

As a rule, these parameters must be determined by process engineers who develop technological processes involving compressor equipment.

For example, air flow can be calculated as follows:

1. Calculation of the amount of air in continuous operation.
2. Making adjustments to the obtained value, taking into account the operating time of the equipment per shift or day.

When selecting equipment, it is necessary to take into account the increase in the number of compressed air consumers.

Control systems for compressor equipment

To ensure that the air is under constant pressure in compressor systems, control equipment is installed. The simplest system consists of a pressure sensor and a simple tuning system. It allows you to maintain a constant pressure in the receiver. If the set parameters are exceeded, the compressor is turned off, and after the pressure has dropped to a certain minimum, the automation is activated and the compressor turns on. Such, or almost such systems, are installed in almost all compressor installations. Their presence ensures the safe operation of the equipment.

home appliances

To perform certain work that is performed at home or in the garage, household compressors are used. As a rule, these are small-sized electrically driven reciprocating compressors. The power of such a product is 2.2 kW. Such compressors are able to pump air up to 8 atm.

For the most part, they can safely provide a pressure of 10 atm. To store compressed air, receivers with a capacity of up to 100 liters are used.

As a rule, they are used when performing painting works, internal and external.

Why are piston compressors needed?

Air piston compressors are mechanical devices used to compress air from the atmosphere by reducing its volume. Compressed air is stored in a storage tank or released into the pressure system - into operation.
The process of compressing the air causes the air molecules to move faster in a smaller volume, and a further decrease in the external pressure will cause the air to escape quickly.
That is why compressed air is a source of energy. The most common type of compressor is one that uses either very little or very high power.

Compressors have two components: a compression mechanism and a power source for the compression mechanism.
The energy for compression can be taken from gas, from an electric motor, or from a power take-off.
The various compression mechanisms that do the actual work of compression are pistons, vanes and impellers. By storing and compressing air, air compressors convert mechanical energy into pneumatic energy. they even make some natural gas-driven products, which are great for reducing cost and energy consumption.

Manufacturers of air and reciprocating compressors provide an efficient type of power generator for various industrial processes and pneumatic power systems. For example, in industrial installations, compressors provide the necessary air for air cleaning systems, air lock systems, blowers and temperature control systems.

Air compressors make cleaning easier with air hoses or other cleaning systems. Air pumps from compressors are also a quick and effective way to inflate bicycle and car tires both at home and at gas stations.
Gas stations use compressors for gas pumps (petrol pumps).

Airbrushing (paint sprayers) also uses air compressors - in car dealerships, commercial and private airbrushing.

Sandblasting machines run on compressed air. Other tools that use compressed air include nail guns, belt sanders, drills, staplers, and spray guns.
These powerful appliances don't have big motors and thanks to the compressors they are light and easy to work with.

Compressors are in great demand in industry and construction. They are used in medicine and dentistry. In every household refrigerator and air conditioner, the compressor plays the role of the main driving mechanism. The production of compressor equipment is considered a separate industry that is rapidly developing, absorbing the achievements of electronics and new technologies. Knowledge about the device, operating rules and technical service will help you make the right choice when buying a compressor, as well as solve problems associated with repairing a failed unit.

What is a compressor and how does it work

The name "compressor" comes from the Latin word compressio, which means compression. This is a device for creating increased gas pressure and supplying it in the right direction. Depending on how the task is achieved, compressors are divided into groups. A distinctive feature of each type of these devices is a constructive solution for the process of compression and air supply. In general, all units are divided into two large categories - volumetric and dynamic. Each group, in turn, has its branches.

The variety of compressor machines is due to the wide range of their application.

Dynamic compressors are based on the principle of compressing gases by means of mechanical energy. There are axial and centrifugal machines depending on the direction of air movement, as well as on the type of rotating wheel. One of the brightest representatives of this group is the turbocharger. Its design is based on the interaction of moving air with a fixed grate and rotating drive blades.

In dynamic compressors, the gas is compressed due to mechanical energy supplied from a rotating shaft.

Displacement compressors use the property of gases to compress when the size of the enclosed space in which it is placed changes. Reducing the dimensions of the working chamber leads to an increase in pressure. This group includes most household and industrial units, there are more than 10 different types:

1. Piston. The most common type of injection machines that serve to supply gas or steam under pressure. There are a lot of design solutions, but the main feature of a piston pump is the compression of the working medium due to a decrease in the volume inside the cylinder, produced by the reciprocating movement of the piston. Such compressors are used in heavy engineering, chemical, textile and refrigeration industries. By design features, piston devices are classified into vertical, horizontal, angular. There are multi-stage reciprocating compressor stations - when compressing gas to high pressure, there is a risk of explosion or ignition of oil deposits accumulating in the pipeline and the surface of the exhaust valves, so this procedure is carried out in several stages.

   A reciprocating compressor increases the pressure of a gas by reducing its volume during the stroke of the piston.

2. Screw. Experts consider this type of machine the most economical. That is why screw compressors are used in mobile compressor stations, mobile military equipment, ship refrigeration equipment. Compared to other types of blowers, energy savings can reach up to 25-30%. In addition, there are small dimensions, reliability and low cost. The essence of the design consists in two coaxially rotating rotors made in the form of an Archimedes spiral. The screws move synchronously, do not contact each other, and do not need lubrication. Inside the rotor housing there are gas suction and discharge channels, as well as seals and plain bearings. The gas is compressed in portions as the chambers are filled and is released into the storage tank. Thanks to this, the unit has a high performance. Recently, not only twin-screw, but also four-screw compressors have become widespread, the productivity of which is even higher. According to experts, with this design, additional savings of 10 to 15% are achieved.

   A screw compressor pumps air under pressure due to the synchronous rotation of two shafts with screw blades.

3. Rotary gear. They are characterized by a long service life, a relatively simple design, balance and a high level of purity of the injected gas. They are used to supply air to internal combustion engines, replacing plate models. The rotary gear compressor is distinguished by the optimal dependence of the outlet pressure on the speed of the rotating rotors, which favorably affects when the engine operating modes change. In the process of transferring air from the suction valve to the exhaust valve, the pressure practically does not change, therefore such devices are called external compression compressors. As a consequence, this kind functions effectively only for a small level of operating pressure change. Other disadvantages are the presence of pulsations in the forced air flow and high noise during operation. If the gaps between the parts are violated, a sharp drop in the efficiency of the unit is observed.

   Rotary gear compressors can be designed with water or air cooling

4. Membrane. This is a type of volumetric instrument, which is very well suited for raising the pressure of a small amount of vapors or gases to a low level. As the name implies, the main working mechanism in this type of compressor is a flexible membrane made of rubber, rubberized fabric or metal. Fluctuations are caused artificially, with the help of mechanical action. It can be provided by a rod driven by a connecting rod or hydraulics - a column of liquid resting against the lower part of the movable membrane. Devices of this type are used in industry and in laboratory research. The duration of operation directly depends on the quality of the material from which the membrane is made. Often, multilayer composite materials are used that can withstand repeated vibrations and deformation.

   The membrane compressor compresses air due to a flexible membrane that vibrates from the mechanical action of a reciprocating rod

5. Liquid ring. They are used in agriculture and the food industry (for the production of sugar, yeast, soft drinks and bread). Due to the design features, they protect the air well from pollution by oil vapors. Despite the low efficiency and increased dimensions, water ring compressors are reliable in operation, do not produce much noise and, most importantly, they compress the gas with little or no heat release, i.e. isothermally. The principle of operation is based on the compression of the air mass by a more viscous liquid. Structurally, this is achieved using a cylinder filled with liquid (water), in which a rotor with blades rotates. The crescent-shaped space, divided into segments by blades, is the functional volume of the apparatus. The intake air is compressed and forced out through the compressor outlet.

   Industrial compression systems use the principle of compressing air with water.

6. Roots blowers. Low pressure compressors patented by the Roots brothers in 1860 in the USA. A simple and effective design, which has been improved and modified many times over time. Nevertheless, these units are used in technology to this day. Their output figures reach 16,000 m 3 /h and an additional pressure of 1,000 Mbar. A distinctive feature of Roots blowers is the lack of lubrication in the working mechanism. A minimum of rubbing parts makes the mechanism very reliable in operation. The low vibration level and compactness make it possible to use the unit for pumping aggressive and explosive gases. It is driven, as a rule, by an asynchronous electric motor.

   In the Roots blower, the work of moving and compressing the air is performed by a pair of rotors with helical blades.

7. Spiral. Compression of the working gas medium occurs due to the interaction of two spirals that move eccentrically next to each other. Since the spirals do not touch and there are always gaps between them, the motor resource of this type of compressor is quite large. However, during assembly and commissioning, stringent requirements are imposed on the manufacturer. Violation of technological gaps of a few fractions of a millimeter can lead to the functional unsuitability of the structure. The frequency with which the spiral moves is estimated at several tens of thousands of revolutions per minute. The disadvantage of the spiral design is the need to run in the internal "snail" at the initial stage of operation. Compressor run-in is necessary to smooth technological gaps. This affects the overall wear of the working pair.

   In a scroll compressor, operating clearances are measured in fractions of a millimeter, so such devices require careful running-in

8. Rotary. A variety of volumetric units in which there are no suction valves, but only discharge valves are used. The axis of the rotor (piston) rotates around the axis of the cylinder, which is stationary. As a result, a so-called crescent-shaped space is formed, in which gases or vapors are compressed.

   In a rolling rotor compressor, the working cylinder is stationary, and the piston rotates around it.

The creation of the scroll compressor dates back to 1905. The idea belongs to an engineer from France Leon Croix. But the introduction into the industry was possible only in the middle of the 20th century, when the level of technology made a serious step in the field of material processing. The design received mass application at the end of the century, when scroll compressors began to be used in climatic and refrigeration equipment. It turned out that the efficiency and the level of pressure created by this type of units are superior to all other devices known at that time.

In addition to the above classification, there are other ways to separate compressors:

• by type of drive mechanism (electric drive, internal combustion engine, turbine);
• by outlet air pressure (compressors of low, medium, high and ultra-high pressure);
• by productivity, expressed in the amount of volume of compressed gas (in m 3) for a certain time (min., hour).

How to choose a compressor

Obviously, the choice of compressor depends on the intended purpose. No one will use a car compressor, for example, in a refrigerator or vice versa.

The main consumers of atmospheric pressure machines are motorists, master builders, locksmiths, and furniture makers. As practice has shown, screw and piston compressors are most suitable for their needs. Moreover, oil-free ones are used for small amounts of work - tire inflation, painting small body parts, etc., and more powerful ones are used for pneumatic tools - oil piston and screw compressors.

Piston injection machines appeared earlier than others and are still the most common.

The working pressure of such units reaches 25–30 atmospheres, which other compressors cannot boast of. The main advantages are low cost, simplicity of design and ease of repair. In addition, the devices are insensitive to the composition of the air environment - dust, moisture and temperature changes practically do not affect the quality of work. Service life at the correct operation and timely service very long. The disadvantages of reciprocating compressors include the need for regular replacement of parts that wear out quickly - piston compression rings, seals and valves, as well as a high level of noise pressure, which reaches 95 dB (this is comparable to the roar of a locomotive going by rail). In industries that intensively use such compressors, special rooms are allocated to accommodate "noisy" equipment. Based on the listed features, piston machines are used in the following cases:

Screw compressors compare favorably with piston compressors in that there are no wear parts in the design. The block of screws, which is the main working mechanism, is designed for a service life of 15–20 years without major repairs. The absence of reciprocating parts and valves makes screw compressors very reliable and durable. The dynamics of the compressed air supply to a lesser extent depends on the speed of rotation of the drive shaft, while in a reciprocating compressor, the slowdown of the piston stroke leads to pressure dips. Due to the fact that there are no pistons and connecting rods in the design, vibration and noise are reduced. Therefore, such units do not require a separate room for installation. In addition, the compressor radiates a large amount of heat, which is generated during the compression of gases. It can be used to heat the workspace during the cold season. The cost of screw compressors is an order of magnitude higher than piston compressors. This is due to the more complex production. But such equipment pays off faster, as it is more productive and economical. The use of "screws" is justified in cases where large amounts of compressed air are needed in an uninterrupted mode.

The main parameters that you should pay attention to when choosing a working tool:

1. The pressure generated by the compressor. One of the most important parameters by which you can judge the performance of the product. Pressure is measured in atmospheres (atm.) or in bars. In order not to get confused in units of measurement, you need to know that one atmosphere is approximately equal to one bar. Knowing the maximum pressure value of the compressor, you can determine which tool it will fit. In practice, a compressor is always purchased with a margin. If, for example, a pneumatic wrench is driven by an air pressure of 6-7 bar, it is recommended to choose a compressor that compresses the air up to 10 bar.

   The wrench is driven by compressed air supplied from the compressor

2. performance level. It is expressed in liters of air pumped per minute. Attention should be paid to the fact that in piston machines there is the phenomenon of "air failure" - a decrease in productivity during operation associated with changes in the external air environment. Therefore, such a compressor is chosen with a performance margin of up to 20% of the nominal.
3. Power. A value indicating the operating potential of the equipment. In simple terms, power refers to the speed at which a machine can handle a job. It is measured in watts and is displayed in the technical data sheet of the device. As in the first two cases, the calculated power value must include an error for the difference between the nominal and real value. Over time, due to wear of parts and engine exhaustion, power decreases, which can lead to incompatibility with the working tool. Based on this, it is recommended to purchase compressors with a capacity exceeding the specified one by 20-25%.
4. receiver volume. Immediately after compression, the air enters the storage metal tank, which serves to stabilize the air supply. In technical terminology, it is called a receiver. The larger the volume of the receiver, the less pressure drops will be during operation. But it should also be borne in mind that the compressor will take more time to pump the required amount of air into the sealed container.

   Depending on the power and performance, compressors can be equipped with receivers with a volume of 25 to 250 liters

5. Rated operating voltage and current. In domestic conditions - where there is no three-phase current connection - single-phase equipment is used, designed for a voltage of 220 V and a current of 6 A. In domestic networks, the current frequency is 50 Hz. When purchasing an imported compressor, you need to make sure that it is compatible with these parameters. Otherwise, overheating and premature failure of the tool may occur.
6. Weight. As a rule, it is directly related to the power and performance of the compressor. Household models, designed for home and "garage" use, have a mass of up to 5 kg. Such a compressor is more mobile, easy to move and transport. Professional models installed permanently weigh 20 kg or more.
7. Dimensions. This indicator is directly related to the weight of the compressor. Ease of use depends on the size of the device. If you need to move frequently, it is advisable to choose a small compressor with a carrying handle. Powerful and heavy devices with large volume receivers are installed on mobile platforms that roll on wheels.
8. Noise pressure indicator. It is believed that a comfortable and harmless noise level is up to 70 dB. Many manufacturers, solving this problem, use additional noise-reducing and anti-vibration designs. Information about the noise level is reflected in the technical passport of the product.

Video: how to choose a compressor for home and garage

Table: pneumatic tool parameters

Video: how to choose a compressor for pumping car tires

How to use the compressor

Preparing the compressor for operation is an important step, the observance of which is associated with long-term and proper operation. It consists of the following successive steps:

1. Careful study of the instructions supplied with the product by the manufacturer. The data given in the technical passport must match the data reflected on the metal plates. They are located at the bottom of the compressor housing.
2. Checking the complete set and the absence of mechanical damage on the case. If defects are found in the housing, receiver or connecting hoses, they must be eliminated.
3. Installation in working position. Wheels and shock absorbers are put on mobile models in accordance with the configuration. The unit is located in such a way that control is carried out smoothly and easily. No foreign objects on the body are allowed. If the compressor has a belt drive, it must be installed at a distance of at least 1 m from the walls. The floor surface in the room where the work is performed must be flat.
4. Checking the oil level in the crankcase. The red label indicates the maximum allowable amount of grease. If there is not enough oil, it is necessary to carefully add it, without overflowing and avoiding contact with the belt and other parts.

   The oil must be filled up to the level indicated by the red mark.

5. Connecting the machine to mains power. In some devices, it is important not to confuse the connection of the phase and neutral wires.
6. Connecting the receiver nozzle to the fitting of a pneumatic tool. When properly connected, the air bleed triggers the engine start relay automatically. Independent adjustment of the relay is unacceptable and terminates the warranty on the part of the manufacturer.
7. Devices equipped with a motor overload protection function are switched off if they run for too long or if there are voltage fluctuations in the network. You should remember this and not look for the reason for the stop in the mechanical part of the apparatus.
8. After finishing work, the power unit must be completely turned off and excess air must be released from the storage tank (receiver). For this, a special valve is installed on the tank body.

   After completion of work, it is necessary to bleed excess air from the receiver by opening the check valve

Some compressors use a dipstick instead of an oil level gauge. To determine the presence of lubrication, the probe is lowered into a special hole closed with a plastic cover.

If it is not possible to connect a car compressor from a regular cigarette lighter or you need to save battery power, it is possible (and in some cases recommended) to connect the terminals directly to the battery. For this, special clamps are used, which are included with the tire inflation compressor.

Safety

Before starting work, you should:

• put on work clothes, shoes and collect hair under a headdress;
• check the completeness and stability of the device;
• make sure that the pressure gauge and the pressure safety switch are in good condition;
• equip the workplace in accordance with personal safety standards.

While working with compression equipment, it is prohibited:

• connect to an electrical network without grounding;
• leave a running compressor unattended;
• direct the air stream towards people;
• allow children and minors to control the compressor;
• use a known defective unit.

After completion of work it is necessary:

Compressor care

Compressor maintenance consists of the following scheduled maintenance:

Video: how to change the oil in a piston compressor and maintenance

The most common breakdowns and do-it-yourself repairs

If the compressor was purchased recently and the warranty period has not yet expired, all breakdowns must be eliminated by the employees of the service organization. But if the warranty is over and you have to repair the equipment yourself, study the table below.

Table: Compressor malfunctions and solutions

How to make a compressor with your own hands

Craftsmen have long learned to make compressors with their own hands. Some self-made devices are able to perform work no worse than factory ones. As a rule, gas cylinders or fire extinguishers are used as receivers. And the role of the injection machine is played by the compressor from the old refrigerator.

The simplest apparatus for the production of compressed air consists of a compressor from an old refrigerator, a gas cylinder and a pressure gauge.

The performance of such a device will be small, but it can be used to apply a uniform layer of paint on any surface. For this, either a spray gun or an airbrush is used.

Video: how to make a compressor from an old refrigerator

When using pneumatic tools, as well as sandblasting devices, remember that if handled carelessly, the compressor can turn from an assistant in the household into a dangerous device that can cause injury or become a health hazard. Only compliance with safety standards and a careful attitude to work guarantees personal safety.

What questions will you find answered in this article:

Introduction

As a rule, the choice of a compressor begins with the understanding that there is a need to use pneumatic tools for any work that requires compressed air at the inlet. Just this problem is solved by buying a compressor. And it does not matter whether it is a compressor for a car service, tire fitting, car wash, hobby, garage, or a professional compressor for construction or medicine.

So, you understand that you need a compressor. Enter in the search bar "buy a compressor" and get hundreds, or even thousands of offers of this technique.

This is where the hardest part starts. The characteristics of compressors vary considerably, as does the cost of the equipment. The price of a compressor starts from 3-5 thousand rubles and goes for several hundred thousand, and this is not the limit.

How to choose a compressor for your needs, so that it works as long as possible, uninterruptedly supplies all your consumers with compressed air and fits into the optimal budget?

In this article, we will try to explain as much as possible about what characteristics a compressor has, how they relate to the technical characteristics of consumers, and how best to choose a compressor for a car wash, service station, garage and other purposes.

What are the types of compressors?

In all the variety of compressors, they are divided into several characteristics according to the principle of operation, so:

Piston compressor- the principle of operation is similar to an internal combustion engine, where air is pumped due to the movement of the piston on the connecting rod mechanism. Most household and semi-professional compressors are reciprocating compressors. As a rule, a piston compressor is chosen for a car wash, a small service station, tire fitting.

Screw compressor- the principle of operation, roughly can be compared with a meat grinder, where the propeller blades work in a chamber with a minimum gap, thus forcing air. This category refers to expensive professional (industrial) compressors. They have a much higher resource, performance, lower noise level. Screw compressors are usually used in large service stations, where there are a large number of consumers of compressed air, or in industry.

What are the differences between reciprocating compressors?

Oily and oil-free.

In oil compressors, there is a crankcase with a lubricating fluid, which increases the life of the engine, and also has a lubricating effect on the direct consumer, whether it is a wrench, impact wrench, grinder, polisher, screwdriver, etc. The same effect has a negative effect when using a spray gun, when oil particles can get into the spray gun and reduce the quality of painting (it is solved by installing additional filters in the pneumatic line in front of the spray gun). Accordingly, like any equipment using oil, this type of compressor requires additional care, control and timely oil change. Most of the compressors used in a car wash or service station are oil compressors.

Oil-free compressors are easier to maintain and are used, as a rule, for personal needs in garages, or for hobbies. The resource of oil-free compressors, as a rule, is 2-3 times lower than oil compressors, and the operating mode involves the use of a compressor for no more than 10-15 minutes per hour.

With direct drive (coaxial), with belt drive.

Small compressors of small capacity, up to 400 l/min, are usually with direct transmission, i.e. the piston shaft is located directly on the motor shaft, and the engine speed is equal to the piston speed. This design characterizes increased wear of the engine and resources for this type of compressors below the product with a belt drive.

In compressors where the rotation of the pistons is transmitted through a V-belt drive, the motor speed is lower, thereby achieving an increased resource and compressor performance. But their cost is already higher.

Number of cylinders

Compressors are 1-2-3 cylinder. The performance of the apparatus depends on the number and volume of cylinders. Compressors can also differ in in-line, V-shaped, W-shaped arrangement of cylinders, but in this article we will not delve into these features.

How and by what parameters to choose a compressor?

So, we came to the conclusion that we need a compressor. Which to choose? We will talk about compressors for a car wash or car service, therefore, single-piston direct-drive compressors with a capacity of up to 200 liters per minute and a pressure of less than 6 bar. we will not consider (the blow gun alone consumes 100-250 liters per minute).

Consider the standard characteristics of one of the compressors manufactured by Remeza, so:
Compressor SB 4/S-100 LB 30, 1796150, Remeza, article 011034

Pressure

We immediately pay attention to pressure. The pressure (atm), which is indicated in the characteristics of the compressor, characterizes the limit value that you can get from this unit. Most compressors have pressure regulators, and you can adjust it down the outlet line to suit your needs. Of course, it will not work to increase the pressure above the value indicated in the compressor characteristics.

Most compressors used in car washes and car services have pressure values ​​​​of 8-10 atm in their passports. In addition, it must be taken into account that the operating pressure of the compressor will differ from the peak pressure by about 20% downwards. The passport value of the compressor pressure is indicated in (Bar) or (atm). In this case, the relationship between these quantities is as follows:

• 1 atm = 1.013 bar
• 1 Bar = 0.9869 atm

That is, by and large, it is not very important in which of these values ​​the pressure will be expressed for a particular compressor model - they are very close and an error of 2-3% is not significant in this case.

Thus, it is highly desirable that the compressor according to the passport exceed the required working pressure of the tool by 15-20%.

Performance

The most significant characteristic when choosing a compressor is the compressor capacity, which is usually measured in liters per minute (L/min). We select this parameter based on the number and volume of the tool that is planned to be used.

It is also necessary to know that the performance at the compressor inlet is indicated in the passport, i.e. the volume of "sucked" air. And we need output performance. To evaluate the output performance, you need to multiply the data specified in the model description by a factor:

• Oil-free single-cylinder compressor with direct transmission - 0.35-0.4
• Direct Drive Oil Compressor - 0.6-0.65
• Oil compressor with belt drive - 0.7-0.75

When choosing a compressor for several units of pneumatic equipment, it is important to take into account the fact that it is very unlikely that all consumers will be used simultaneously. For this, the equipment synchronism coefficient is used in the calculations:

How to calculate the required compressor capacity:

Q=(Q1*Ki1+Q2*Ki2+Q3*Ki3+...+Qn*Kin)*Ks, where
Q - required output compressor capacity,
Q1...Qn - air consumption of each consumer
Ki1...Kin - utilization rate of each consumer, total:
Кс - coefficient of synchronism of the equipment.

Example:

You plan to use 4 blow guns and 2 cyclones at your car wash, we calculate the required performance using the formula (we will take the maximum values ​​for the cyclone and blow gun):

Q=((270*0.3)*2+(250*0.3)*4)*0.81=374.22 l/min.

With such a capacity, an oil compressor of a belt type is needed, respectively, it is necessary that in the passport data it should have a performance of at least: 374.22 / 0.75 = 498.96 liters., so we need a compressor with a performance according to the passport of at least 500 l/min.

Compressor power. Voltage.

The compressor power in the product data sheet can be indicated in horsepower (hp), or kW. The ratio between these units: 1 HP \u003d 0.735 kW, 1 kW \u003d 1.36 hp

Compressor power - characterizes, to a greater extent, the performance of the compressor. The more performance, the more power it has. Accordingly, it is not a characteristic that should be focused on when choosing, in the first place. It is obvious that the greater the compressor power, ceteris paribus, the more resource it will have within the framework of the task.

The voltage is 220V or 380V. As a rule, powerful industrial compressors are 3-phase with the required mains voltage of 380V. If at your facility there is no way to connect the compressor to a 380V network, then it makes sense to consider a household compressor designed for a 220V network.

The volume of the receiver (air collector).

An important parameter of the selected compressor is the volume of the receiver that is installed on the compressor. In household, semi-professional, there are receivers from 3 to 50 liters (the most common 24.50 liters).

Professional compressors have receivers for 100, 200 or more liters. As a rule, car washes and service stations use compressors with a receiver volume of at least 50-100 liters. The presence and volume of the receiver makes it possible to reduce pressure surges that occur in the line when the electric motor is started, as well as reduce the frequency of switching on and the duration of the operation of the motor itself, thereby extending the life of the compressor. When choosing a compressor, we recommend that you initially decide on the optimal size of the receiver, which is necessary for your tasks. Of course, the receiver can be bought and installed additionally, but it is more convenient and easier when the compressor is initially selected correctly, according to the needs of air consumers.

• In other words, if you need a small compressor for your home, garage, hobbies and planned work - this is tire inflation of your car, or airbrushing - a small receiver up to 10 liters will be enough.
• If you plan to use one device (grinder, pneumatic drill, spray gun, blow gun), it is quite possible to stop at a 25-50 liter receiver.
• If it is planned to use 2 or more units of compressed air consumer, it is necessary to consider the volume of the receiver 50, 100 or more liters.

We hope that this review will help you make the right choice when deciding to buy a compressor, which compressor to choose. If you still have questions, or need help in choosing a compressor for a car wash or other type of business, please contact our managers, they will help you make the right choice!

You can always choose and buy a compressor with delivery in the compressors section on our website. Compressors from leading manufacturers such as Fiac, Remeza, AE&T with pressure from 6 to 10 atm, capacity from 24 to 2000 liters per minute and receiver volume from 24 to 500 liters are presented.