Compressor for a spray gun: selection, device, features, types

Car painting is a fairly complex production process in which reliable tool performance plays a key role in ensuring good results. In a small garage and in a huge service station, almost identical spray guns can be used to work on cases and other assembly elements. However, different goals, volumes of operations performed, and their nature impose inevitable differences in the superchargers, piping and other equipment used. Therefore, choosing a compressor for painting is a task that needs to be solved very carefully.

Design and principle of operation

The name of the mechanism in question determines that it works based on the supply of compressed air, which is mixed with a dye. That is why such a device also has a compressor with a receiver. When choosing a compressor for a spray gun, you should pay attention to the following points:

The spray gun itself is represented by a spray nozzle, which is designed in the form of a pistol. At the top or bottom of the structure there is a place to install a tank for storing the dye.
The receiver is connected to the sprayer using a special rubber hose. It has fairly high strength, is flexible, and is designed to supply air under a certain pressure from the generator to the actuator.
In the sprayer, air is directly mixed with the dye, which is broken into small particles. This results in a high-quality coating.
The shape of the mechanism is created in such a way that the air flow spreads like a torch, diverging at a certain angle in all directions.

Particular attention is paid to the fact that devices must be manufactured using high-quality materials.

How long they will last depends on this moment.

The sprayer has a rather complex design. It consists of the following elements:

Pendant.
Channel for supplying substance.
Nozzle.
Channels designed for air supply.
Air type head.
Tank for storing dye.
A regulator that allows you to change the parameters of the resulting torch.
A regulator responsible for the direct supply of paint.
Air supply regulator.
Lever.
Connection for direct hose connection.

A fairly simple principle of operation determines that the mechanism can last for a long period.

Equipment options for various fields of activity

You can get lost in the numerous variations and sets of components for building an effective air supply system. Therefore, it is worth giving a few simple recommendations and templates for average solutions.

For domestic use in periodic mode, a piston oil compressor is perfect. Today there are many options for ready-made stations on sale that supply air with a pressure of up to 8 bar. Such kits are equipped with a receiver with a volume of 6 to 100 liters (it is recommended to choose at least 50 liters), and are capable of operating for 20 minutes every hour.
Semi-professional class compressor stations are built on oil piston compressors with coaxial or belt drive and are equipped with a receiver with a volume of at least 50 liters. They also cannot be operated continuously, but the effective operating time is up to 40 minutes every hour. The average maximum pressure is up to 16 bar.
Industrial (professional) equipment does not have a clear gradation of parameters. As a typical feature, we can note the huge volumes of receivers - up to 1 cubic meter. Such stations can operate continuously, and you can purchase equipment with characteristics that satisfy any need.

For purely one-time garage work, you can assemble a compressor station with your own hands. To do this, you will need to purchase moisture and oil traps, a reducer, a pressure switch and find an empty gas cylinder in good condition. The main supercharger in a homemade station is a compressor from a refrigerator. This device belongs to the piston oil class.

After dismantling the refrigerator, the old oil is drained from the unit and modern synthetics are filled in. After this, the output tube is connected to the receiver, and the power system is switched through a thermal relay. A mini compressor of this class is capable of satisfying minimal garage needs.

Compressor Features

Today, the equipment in question has become very widespread in a wide variety of industries. Among the features of such a device, we note the following points:

To create pressure, a motor is required, which is powered by an electrical network. The compressor engine for a spray gun is characterized by power consumption, design and many other features. As the power of such an element increases, so does the productivity, as well as the amount of electricity consumed.
The design of the compressor for the spray gun itself may differ in a fairly large number of ways. An example is that air is pumped when the screw rotates or the piston moves.
Attention is paid to what type of materials are used in the manufacture of the main parts. The most commonly used is stainless steel, which is characterized by increased resistance to corrosion.

When purchasing paint sprayers with a remote compressor, attention is paid to the power indicator, as well as performance, and the recommended area of application. There are simply a huge number of different models on sale, which are classified according to design characteristics.

What should the torch size be?

To achieve maximum efficiency when painting, experts recommend applying the paint layer using a torch of the maximum size. The larger the width of the torch, the more uniform the layer of paint applied to the surface is. To achieve the maximum width of the torch, it is necessary to unscrew the adjusting screw to the maximum in the “+” direction.

If you need to paint a small part or part of a car body, then you should reduce the size of the torch. It is important to remember that the position of the adjusting screw at “—” ensures the application of a paint layer in the shape of a circle. When the regulator is turned to “+”, an oval shape of application of the paint layer with an increased width is obtained.

Oil-free piston compressor

Piston-type designs have become quite widespread. A similar compressor for painting with a spray gun can be purchased at various specialized stores; special attention is paid to oil-free devices. The design features are the following:

The device has a fairly large body, which is made of steel or cast iron.
Inside there are moving elements represented by a piston. They perform a reciprocating movement, due to which the required pressure is created.
A working chamber is required to create a volume in which air accumulates.
The movement is transmitted using a rod; an electric motor is used as the source of movement.

A feature of the considered version of the compressor for the spray gun is that there is no lubricant between the moving and stationary elements. This is due to the fact that it can enter the working environment, significantly reducing its performance.

Oil in the system is required for the following reasons:

Cooling.
Reduced wear.

In this case, the device operates without lubricating fluid. That is why such a compressor for a spray gun cannot last for a long period; it needs to be allowed to cool down.

Test Spray

Having adjusted your spray gun and selected the optimal nozzle, do not rush to start painting the required object.
To make sure the settings are correct, do a few test sprays on paper, cardboard, or other vertical surface that you don't mind getting dirty. It is necessary to carry out this procedure to assess the shape of the torch, the uniformity of application and distribution of the material over its area. The most important test is considered to be the form check, and we will look at it first. Imprint shape

The spray gun torch, ideally, is an elongated oval with slightly blurred edges. The width can vary between 200-400 mm. The paint transfer must be uniform over the entire spray area and form an even print, without depressions or bevels.

When spraying, the spray gun must be held at a certain distance: 10-15 cm for HVLP, a little further (15-20 cm) for LVLP, and as far as possible (20-25 cm) for conventional sprayers (HP).
It takes no more than a second to open the paint supply. If the torch of your spray gun has the above distortions, you should know that they are caused by unregulated air pressure, clogged or defective nozzle. The dumbbell-shaped figure eight indicates increased air supply, which is corrected by lowering the inlet pressure. Too much paint accumulation in the center can be reduced by tightening the appropriate adjustment screw. If one of the air cap holes is clogged or defective, the torch spot takes the shape of a banana, which can be eliminated by cleaning or replacing the element.

Paint distribution

the area of the sprayed spot affects the uniformity of the layer and is checked quite simply. To do this, turn the air cap 90° (for horizontal spraying), and press the trigger for 2-3 seconds until smudges begin to appear. If the drops are evenly spaced and have the same length, then the dispersion of paint molecules is correct and does not require additional calibration. If smudges predominate in the center or on the sides, the air or material supply should be adjusted.

Spray quality
is a subjective indicator of the effectiveness of a pneumatic spray gun and is determined based on the size of the droplets transferred to the object. The size of the mixture particles can vary, increasing from bottom to top. Increasing the inlet pressure increases paint dispersion and reduces the layer size, making it rough and “dry”. To ensure that the spray gun layer does not cause any complaints, use the optimal operating pressure.

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Piston oil compressor

To reduce the degree of wear of the device, as well as to eliminate the possibility of overheating of the moving elements of the piston system, oil is added. It is worth considering that there are special oils on sale that are intended for use in compressor units for spray guns. The features of such models are the following:

Cooling of moving and rubbing elements is ensured. Due to this, the structure can last much longer without interruption for cooling.
The degree of wear of the structure is reduced. As practice shows, correctly selected oil increases the service life several times.
The permissible maximum load at which the equipment can operate is increased.

In order to ensure reliable operation of the entire system, a filter is installed. Its purpose is to separate oil from air, as it significantly reduces the quality of the paint material.

Popular models

Compressor units have different characteristics and prices. There are the most popular models that have proven excellent performance.

"Kraton" AS-140-8-OFS

This relatively inexpensive compressor with a coaxial drive is useful not only for painting, but also for inflating tires . The design is equipped with an air filter that removes recycled oil. The built-in fuse will protect the installation from overloads. The electric motor is equipped with special protection to prevent overheating. Rubber pads on the legs reduce vibration. The installation weighs only 15 kg. The compressor runs quietly. It is compact and easy to transport, as it is equipped with a special carrying handle. The cost varies from 6,000 to 8,000 rubles.

Screw compressor

Screw compressors for spray guns have become very widespread in industry. The pressure in this case is created by the rotation of two screws. The advantages of this design option are:

Low oil consumption compared to the option with moving pistons.
During operation, vibration and noise are significantly reduced. That is why installation does not require a special foundation, which simplifies installation work.
The cooling efficiency is significantly increased, since the procedure is carried out automatically. In addition, if necessary, the heat can be reused to heat rooms.
High performance also determines the wide distribution of the device.
Reliability of operation, ease of operation, safety in use and many other points. Most models have an automatic control and monitoring device.

As previously noted, there are quite a large number of different types of screw compressors for spray guns. The classic design is represented by a combination of the following elements:

Filter.
Suction valve.
Screw block.
Belt drive.
Engine.
Oil filter.
Safety valve.
Thermostat.

Such a mechanism can last for a long period.

HP - high pressure group

This is the most common type of paint application device used when working on cars. This is a kind of “classic of the genre”. The output pressure of such a spray gun is about 1.2-1.5 atmospheres.

If we talk about the recommended value at the compressor output, it can be within fairly wide limits - from 2.5 to 5 atmospheres. Here we have a fairly small air flow - it ranges from 100 to 300 liters per minute.

Among the advantages of such devices are the following factors:

the large width of the beam ensures uniform coloring of the surface;
high performance of the spray gun.

Paint and varnish set Miol 80-990 (HP - high pressure system)
Among the disadvantages, experts name the following inconveniences:

low paint transfer rate - up to 45%. The rest of the material is sprayed around without any benefit, bouncing off the surface being painted;
air vortex flows arise that wrap the material, and it lies in such a way that then it is necessary to grind and polish the surface after painting.

Coaxial and Belt Drive Systems

The belt drive eliminates the possibility of engine overload. Among the features we note:

Engine life is extended.
Eliminates the possibility of overheating due to high load.
The structure is large.
Loss of efficiency.

Direct drive reduces the size of the device and also eliminates the possibility of loss of efficiency. However, in this case there is a high probability of engine overload. HP systems have become very widespread.

Why do you need a receiver and how to choose its volume

The receiver is represented by a vessel with air, where it is under pressure. The main purpose is to equalize the pressure when air enters the compressor. Otherwise, a situation may arise where the air mass is transported by pulsation. Due to this, the operational characteristics of the mechanism are significantly reduced. In addition, you can eliminate the possibility of condensation.

When choosing, pay attention to the following points:

Volume.
Equipment performance.
The type of material used in the manufacture of the case.

Do not forget that the mechanism must be securely connected to the system. Otherwise, there is a possibility of a leak occurring, which will cause a decrease in pressure.

Manage procrastination

If outsourcing isn't practical and you find yourself regularly putting off an important task, try turning on a procrastination control mechanism. When you realize you're mindlessly tidying up your desk instead of preparing a client presentation, take note of that moment and try to get back to what's important. Oddly enough, this technique works: just take it and start doing it

Does not exceed? Formulate and write down the consequences of not completing a task.

Oddly enough, this technique works: just take it and start doing it. Does not exceed? Formulate and write down the consequences of not completing the task.

You can set aside 30 minutes a day that you honestly devote to your friends' posts on Facebook. The main thing is to note the end of this blissful half hour and return to solving the problem.

Photo: Unsplash

Another option for dealing with your smartphone getting stuck is to put it away, delete all games, and hide social media icons. After all, there are strict methods such as blockers of individual sites or the Internet as a whole, applications that limit your stay on a specific site. For example, Freedom, Cold Turkey, SelfControl and others.

If you have been procrastinating on a task for a month using all available means, check: is it really related to the strategic goal? Is there a resource? What exactly is stopping you? How to get around this? One client of mine hated cold calling strangers. When meeting in person, such problems did not arise; he was all charm and confidence and could “sell” his interlocutor even a joint project, even a pink elephant.

As a result, it was decided to delegate the “first calls” to the maximum extent possible to the assistant, deputies, or transfer communication to the format of letters and work on the reasons with a psychologist.

How not to ruin the paint: removing impurities

Another important element of the system is the filter. Its purpose is to separate impurities from the environment. Filters are required for:

Oil compartments. Many types of compressors for spray guns operate exclusively with a lubricant in the system. However, it can significantly reduce the quality of the resulting surface. There are special oil filters that are installed in the system.
Removing dust. Air intake is often carried out through a placed nozzle, at the end of which a filter element is also fixed. It separates dust and large particles from the air mass.
Moisture separation. Moisture can also cause a significant reduction in the quality of the paintwork. That is why moisture separators are installed.

Only in this case can the high quality of the resulting coating be ensured.

There are quite a large number of different filters; when choosing, attention is paid to the degree of purification, quality of painting and duration of operation.

Nozzle selection

Setting up the optimal operation of the spray gun is not based on regulators alone. An important part of this process is choosing the right nozzle capable of passing materials of a certain viscosity through it. The larger the diameter of the central hole of the nozzle, the thicker the mixture can be fed through it. If you want to figure out how to set up a spray gun for high-quality painting, it’s definitely worth paying attention to this detail.

You can determine what size nozzle is needed for spraying paint and varnish material from the information indicated on its container. Almost every more or less large manufacturer of paints and varnishes indicates the required nozzle diameter in millimeters with tenths (1.4, 1.5, 2.0, 3.0, etc.). Among the most common types of coating sprayed by a spray gun are:

“Metallic” and other base enamels – 1.4 mm
Primers -1.4 mm
Clear varnishes – 1.5 mm
Epoxy primers – 1.8 mm
Liquid putties – 2.5 mm

The size of the nozzle opening affects the spray volume and the thickness of the resulting layer. If the hole diameter is smaller than required, the coating material will flow with difficulty and the painting speed will drop significantly. When the nozzle, on the contrary, exceeds the required dimensions, the paint is supplied in copious quantities, forming smudges or forcing the pace of work to be accelerated (in such situations, you can get out of the situation by tightening up the supply of material). The choice of nozzle may depend on the “style” of the master’s work. Some prefer to make a thin layer, while others like to specifically fill the part with the mixture. If you are just a beginner, it is best to use the medium nozzle sizes recommended by the paint manufacturer.

Main blower power supply type

Industrial installations in most cases operate on a voltage of 380 V. This is due to the fact that such installations are characterized by high productivity. For home workshops, a design option is suitable that can operate on a 220 V network.

The type of power supply largely depends on the power of the equipment used. Do not forget that three-phase equipment places a serious load on the electrical supply cable.

In conclusion, we note that when choosing a compressor, you should pay attention to the popularity of the brand. Some manufacturers use high-quality materials when producing their products, others try to save money. The resistance of the mechanism to environmental influences will depend on this.

HVLP spray gun category

HVLP (not HLVP!) spray guns are characterized by high volume and low pressure. They were developed in the 80s of the last century, and one of the goals of their creation was to minimize harm to the environment.

The arrangement of air channels in HVLP system paint guns provides for the transfer of at least 65% of the sprayed material to the working surface without loss.

This effect is explained by the high level of pressure at the inlet - 2.5-3 atm. – and its low output value – about 0.7 atm. It turns out that during the operation of HVLP type spray guns, about 25-35% of paint or varnish is lost in the air.

But concern for the environment is not the only quality of these paint sprayers. The advantage of the HVLP system (which is sometimes mistakenly called HLVP) is the significant savings in paint and varnish material, achieved due to the low speed of the paint at the exit. Because of this, less fog is formed, but it is necessary to spray the material at a close distance - no further than 15 cm.

The pros and cons of HVLP spray guns are summarized in a table.

Advantages	Flaws
Saving paint	You need a lot of air (360 l/min or more), which means a powerful compressor
Good environmental performance	Air duct diameter increased
Doesn't produce much fog	Requires the installation of additional filters to clean the air from moisture and oil due to the use of a powerful compressor
Minimum debris on the work surface	Requires high skill to avoid leaks

Disadvantages also include the short range when spraying paint.