Despite the apparent simplicity of the device, it is difficult to determine how to choose a spray gun. Not so long ago this task was a little easier, because only pneumatic devices were on the market, but now electric ones were added with their advantages and disadvantages. To make the right choice between them you need to know their device, the principle of operation, the scope of application and clearly imagine for what purposes they will be purchased.
- 1 The device and principle of operation of a pneumatic spray gun
- 2 Selection of pneumatic spray gun
- 3 How to choose a compressor for a gun
- 4 Electric spray guns - how to determine the type of device
- 5 What parameters of electric spray guns must be considered when choosing
- 6 In which case it is necessary to purchase pneumatic, and in what electric spray gun
The device and principle of operation of a pneumatic spray gun
The very name of this version of the spray guns implies the use of compressed air in their operation, therefore, in the design of the whole device, there will necessarily be a compressor (mainly with an electric motor) with the receiver. The spray gun itself is a spray nozzle in the form of a gun, on top or bottom of which a paint tank is attached. The receiver with a sprayer is connected by a rubber flexible hose, through which air is supplied under pressure. Also, a paint is applied to the atomizer, which is broken by a stream of compressed air into minute particles and blown out of the gun nozzle. Its shape is made in such a way that the flow of air and paint is not direct, but forms a so-called torch diverging at a certain angle to the sides.
1. The trigger.
2. Paint supply channels.
4. Channels of air supply.
5. The air head.
7. Hook for hanging.
8. Flare size adjuster.
9. Ink regulator.
10. Air regulator.
12. Hose connection.
To make this device work without failures, its components must be made of quality materials and precisely matched to each other. All this affects the final price, therefore pneumatic spray guns are mostly used by professionals.
Selection of pneumatic spray gun
There are a lot of controversies on the topic that one should choose first of all - an airbrush or a compressor. You can give different arguments, but it will be more appropriate, depending on the planned types of work, to choose a spray gun, and to it you must choose the right compressor.
The technology of application of a paint supported by a spray gun
The spray gun can be equipped with one of three paint application technologies, differing between the working pressure and the required air volume, which the compressor must produce. The technology used is directly displayed in the abbreviations for the names of spray guns - HP, HVLP, LVLP. Each of them in its own way copes with the main drawback of pneumatic spray guns - the formation of a "colorful fog". It appears due to too much crushing of paint particles that become very light, and on the way from the nozzle of the gun to the painted surface are simply braked by air and remain in it in the form of a slurry.
1 HP (High Pressure) - high pressure.
This technology is used in devices of low price range. It has quite a few shortcomings, because of which it is used less and less, and gradually goes to the background, but with a limited budget, such spray guns are still in demand. The main advantage of such devices is the rapid painting of surfaces due to a large air flow, but their shortcomings are also associated with it:
- A high percentage of paint that does not fall on the surface to be painted is about 50-55%, and this is a perceptible overspending of paintwork materials, plus high air pollution. It is necessary to buy paint more often and to change respirators with protective suits - an obligatory attribute at such works.
- High air pressure requires the availability of skills for using such equipment - if you bring the nozzle of the gun too close to the surface to be painted, the airflow will simply inflate the already applied but not yet solidified paint.
- Although a spray gun working on HP technology is budget-priced, the need for high pressure and high airflow require a powerful compressor.
If you do not pay attention to the question of profitability, high-pressure spray guns are inexpensive and versatile devices that can be used in most types of paint and varnish.
2 HVLP (High Volume - Low Pressure) - large volume of air, low pressure.
The nozzle of the pistol of such a gun is designed in such a way as to lower the high pressure from the compressor at the output. Accordingly, the paint though flies with a lower speed, but in larger quantities per unit time.
Since the airflow is lower, this allows the gun to be kept closer to the painted surface, which receives more paint, thereby reducing the loss of paintwork materials - the transfer factor can be over 65%.
Such devices are much more expensive than high-pressure spray guns, but saving paint more than 15% allows them to pay back fairly quickly.
3 LVLP (Low Volume - Low Pressure) - low air volume, low pressure.
Devices of premium class, with a transfer coefficient of LMC to 80%. This technology does not require the presence of a high-pressure air gun at the inlet, respectively, and a powerful compressor is also not needed - enough and such that it gives out about 200 liters per minute.
It would seem that with lower air pressure, the speed of operation should fall, but this does not happen due to a greater transfer factor. The quality of painting under these conditions only increases, as it requires less control over the distance from the gun to the surface to be painted.
Although LVLP spray guns are the most expensive, but they are indispensable devices when working with premium-segment paint coatings. Even if the paint economy increases by only 5-10% compared to HVLP, with regular work, buying quickly enough will justify itself.
Diameter of the nozzle of the pneumatic spray gun
Depending on the density of the paint, its viscosity and graininess can use nozzles with an outlet opening diameter of 0.8 to 7 mm. Also, this size depends on the size of the painted part - for example, in the ship repairing area or in the car building industry, the ability of the paint spray gun in one pass to apply paint over a large area.
Many manufacturers make spray guns with interchangeable nozzles, but fully monolithic tips for one size are not uncommon - the same professional devices for painting ships will hardly need additional nozzles on the nozzle.
The diameter of the nozzles of professional devices is selected depending on the colors with which you will most often have to work, and the size of the parts to be painted. For household needs, nozzles with nozzles with a diameter of about 1.5 mm are most often needed - they are suitable for the vast majority of varieties of paint and varnish materials, representing a reasonable compromise between the speed of work and the quality of the painting.
As a result, if the set of additional nozzles does not particularly affect the price, then to refuse to expand the functionality is silly, otherwise it is worth figuring out how much they will be in demand.
An obligatory detail of the whole design, which can not always be recalled when choosing a spray gun, although the material from which it is made or location largely depends on the convenience of work:
1 Plastic or metal.
Here it is necessary to take into account such nuances as the weight of the tank and its transparency. The first depends on how much faster the hand will get tired with prolonged work, and from the second - control the level of the remaining paint. According to these indicators, plastic containers are uniquely in the lead and sellers say that they account for a greater percentage of sales.
However, metal also has a buyer - sometimes the requirements for strength outweigh all the rest.
2 Upper or lower position.
When the tank is on top, the paint in the gun is fed by gravity, and at the lower location - absorbed by the air supplied from the compressor. Placement of the tank above or below does not give any improvement in the quality of painting, so the choice between them will only affect the convenience of work.
When the container is fixed from above, the spray gun will have a slightly better weight distribution, but if you stop working, you will have to think about where to put it.
When the tank is located from below, it forms its own support, plus, if you often paint walls near the ceiling, or surfaces with a similar configuration, the spray gun can be raised higher.
Presence of adjustments
Each manufacturer can equip spray guns with various adjustments, the presence and quantity of which is not regulated.
It is mandatory to set the needle stroke regulator, which determines the amount of ink supplied. Limiters of the amount of air supplied, shape settings and dimensions of the paint torch, as well as additional adjustments that can affect the painting process in different ways, depending on the paint materials used, can also be set.
How to choose a compressor for a gun
If the characteristics of the spray gun in many determine the quality of the paint, then everything else depends on the compressor: whether the gun will receive the required amount of air with the required pressure and how long it will be able to work without stopping.
Volume of the receiver
The main objective of this device is to equalize the outgoing air flow (the pump pumps it with jerks) and accumulate the necessary pressure. Here there is a directly proportional relationship - the larger the volume of the receiver, the more stable the airflow and the longer the compressor motor will rest before the pressure drops. On the other hand, the large receiver will take longer to pressurize.
To use spray guns at home, a 25-50-liter receiver is quite suitable - it's the golden mean between compactness, performance and frequency of inclusions in continuous operation - this amount is enough even for professional painters.
The larger volume of the receiver - 100-500 liters - can be needed, only to ensure the operation of production lines.
If there is any doubt about the correctness of the choice, or just need a stock for the future, then you should pay attention to the presence of a connector for connecting an additional receiver - they are often installed in case of need to increase the working volume.
The vast majority of budget and semi-professional compressors are equipped with electric motors with a power of 1.3 kW - with a receiver volume of up to 50 liters, this is more than enough to maintain a working pressure of up to 6 bar. In this case, in the store you can see two seemingly identical engines, but one shows a power of 1.3 kW, and on the other all 1.8 or 2 kW. Of course, there is a temptation to think that a more powerful engine is better - it pumps up the air faster, it's just safer, and the seller probably will say the same. But here one must understand that theoretically it is possible to increase the power of the engine due to the winding quality, but in general, the more powerful it is, the larger its dimensions.
To check the veracity of the words of the seller, it is enough to look at the pumps of these compressors - if they are the same in size, with almost 100% probability this indicates the marketing inquiries of the manufacturer. The fact is that the power of the ratio does not have a relation to the speed of air injection - everything here depends solely on the size of the piston and the number of revolutions of the engine shaft per minute. If the pumps (pistons) are the same, then a significant increase in the air injection rate requires a corresponding increase in speed. Even if the seller insists on the version about the super model of the engine, it must be remembered that a large number of revolutions is proportional to the rapid wear of the bearings and the piston group.
In extreme cases, all the points above the "i" will lay out a full-scale experiment - you just have to bleed the air from the receivers, detect the time of their filling, and then decide whether the overpayment of the promised benefits is worth.
On each receiver, a pressure switch is installed, on which the necessary values are set at which the engine switches on and off. In compressors used for painting works, the lower bar is usually 6 bar and the upper one is 8. This means that when the receiver is less than 6 bar, the engine switches on and pushes air until the pressure rises to 8 bar. The need for greater pressure arises only when compressors are used in production.
As in the case of engine power, there have been no marketing frills, so you have to pay special attention to this parameter. The fact is that there are two types of compressor capacity - the amount of air that it pumps into the receiver from the environment and the volume blown by the gun.
Producers, without a twisting soul, indicate in the characteristics the amount of air that drives the pump through itself, keeping silent about the inevitable compression losses, which reach up to 35%. Accordingly, in order to obtain a real figure, we must multiply the passport by 65% (* 0.65). Those. if the compressor has a capacity of 200 liters per minute, the spray gun will receive 200 * 0.65 = 130 l / min. Also it is necessary to take into account a certain reserve, for which manufacturers of spray guns recommend to allocate about 15%. For example, a spray gun needs 200 l / min, then the calculations will look like this: (200: 0.65) + 15% ≈ 307.7 + 46.15 ≈ 355 l / min.
If you take a compressor with a lower capacity, then either the pistol does not have enough pressure and you will have to do long pauses in the work for air renewal, or the engine will work almost without interruptions, which will accelerate its wear and tear without warranty repair.
As a result - the performance of the compressor is one of the most important characteristics and it should be selected with a margin, taking into account the operation of the spray gun itself, the possibility of connecting additional equipment.
Complementary compressor accessories
Some of the additional functions must be mandatory, and the availability of others depends on the manufacturer. The first include a safety valve that will bleed excess air when a pressure switch fails, and an automatic switch that will shut off the engine when it is overloaded.
In addition, the compressor can be equipped with a pressure regulator, a manometer and air filters. Since the mass of the engine with the receiver is large enough, it is necessary to look at the presence of wheels and the general ergonomics - how convenient it is to move the compressor from place to place.
As a result, the choice of the compressor is reduced to a number of simple calculations, but they must be performed correctly - otherwise you can get a device that does not meet expectations.
Electric spray guns - how to determine the type of device
The types of electric spray guns differ quite strongly from one another in accordance with the principle of action and the form factor, therefore, it is possible to decide which spray guns to choose only if the front of the work for which it is used is precisely known.
Airless electric spray guns
Structurally the electric airless spray gun consists of a nozzle, a valve, a cylinder, an electromagnet, an oscillating bar and a piston. The principle of operation is as follows: the oscillating bar pushes the piston forward, and back it returns under the action of the spring, with the reverse movement of the piston, a diluted space is formed in front of it, where the paint is sucked in, and when moving forward, the paint is pushed through the nozzle to the outside. Since a large number of oscillations and strokes of the piston occur per second, a continuous ink supply is created.
1. Suction tube.
6. Fluctuating bar.
7. Adjusting screw.
9. Piston spring.
With the use of such technology it is impossible to obtain sufficiently small drops of paint - according to this parameter, even a budget pneumatic spray gun wins with a large margin. The advantages of an airless paintbrush in its overall compactness, unpretentiousness and relatively low cost, which makes it a good assistant in domestic conditions.
The principle of the airless spray gun makes it possible to obtain a correct-shaped torch with distinct outlines and to use even high-viscosity varnish-and-paint materials for work.
The characteristics of airless devices determine their scope: for any work in domestic conditions and when it is impossible or impractical to use pneumatic spray guns, for example, when applying viscous formulations.
Air electric spray guns
Such devices are difficult to unambiguously refer to pneumatic or electrical - it's more like a hybrid, taking the best sides from both types of spray guns. This is a standard design that operates by the principle of pressurizing the container with paint, which then passes through the tube and is sprayed through the nozzle of the gun.
From the pneumatic spray gun here is taken the method of applying paintwork materials, which are broken by the air flow and are applied as thin as possible. However, here there is a mini-compressor, which is precisely designed for a pistol. A big plus of such devices is the possibility of alternately using a single spray gun for different types of paintwork materials.
The drawbacks of air electric spray guns are the same as those of pneumatic guns - the emergence of a colorful mist during operation, with appropriate limitations.
Such devices are divided into spray guns with built-in compressor and remote. Spray guns with a built-in compressor have a small size and a low price, but are suitable only for those jobs where high quality coatings are not required.
Devices with a remote compressor are more expensive, but they are more convenient in operation, since the supercharger is located separately and is connected to the gun through a hose. Such devices provide a fairly uniform supply of paint and have a number of adjustments, which allows to achieve good coverage and quality of dyeing.
In fact, these are the same manual spray guns, divided into a gun and pump for paint, but large in size and with characteristics close to professional tools. They are equipped with a powerful electric motor and pump, which are mounted on a separate mobile platform, and the painting is done by a separate spray gun connected to the pump by a high-pressure hose. The paint is supplied from the supplied tank or directly from the bucket into which the hose is inserted.
1. Paint hose.
2. The piston pump.
3. The spray gun.
5. Housing with electric motor.
6. Hose for suction paint.
7. Drain hose.
8. Pressure adjustment.
10. Paint fence.
Such a spray gun has a large number of different adjustments, which allows you to adjust it to work with any type of paint and apply on an industrial scale and in various manufacturing areas.
What parameters of electric spray guns must be considered when choosing
Depending on the types of work planned, it is necessary to select the following characteristics of electric spray guns:
This parameter determines the speed of the entire device - budget models give about 0.5 l / min, middle-class spray guns - from 0.8 to 1 l / min, and floor paint stations can use paints over 2 l / min.
Used paint type
Depends on the type of pump supplying paintwork materials. Most electric spray guns are universal, but there are some of them that are designed to work only with water-soluble compounds.
Since in most manual models the tank is fixed to the gun and when working it has to be kept on weight, it is rare when using a paint tank with a volume of more than 1, a maximum of 1.5 liters. In the floor paint station, the tank may not be - instead there is a place for installing a bucket of paint.
Usually it is metal or plastic - most often buyers prefer the second option, since such a tank is easier and the level of the remaining paint is visible through its walls.
Size of the nozzle
Since the electric spray gun is suitable for work with a large number of paint coatings, a different diameter nozzle is required for different types. For standard enamels, the maximum nozzle size should be no more than 1.3 mm, for acrylic compositions - up to 1.6 mm, and a nozzle with a diameter of up to 2.8 mm will suit the primers.
It helps to paint ceilings and other hard-to-reach places, which otherwise would have to travel up the stairs.
Determines how much you can move away from the compressor, if it's a spray gun with separate blocks or an entire paint station. Buying a long hose, you need to consider how far the paint can "push" the pump with the engine.
Presence of adjustments
Manual models often cost the most necessary minimum - the adjustment of the amount of paint supplied and the shape of the torch. Models with a remote compressor are closer to professional ones in terms of characteristics: several spraying modes, adjustment of the paint pressure at the gun exit, the possibility to change the speed of the piston operation - they clearly benefit in the number of adjustable parameters.
Material of housing and components
Although the electric spray gun is quite a complicated device, it is very difficult to find parts for it - especially for budget models - therefore, with a serious breakdown it is easier to replace it than to repair it. When buying, it's worth making sure that it's made of normal plastic, all the details are adjusted to each other and nothing is loose.
"Buzzing gun" during work can vibrate quite strongly, because of which the hand will quickly tire and the quality of the painting will deteriorate. The vibration level can only be checked by comparing the operation of several devices. Simultaneously, the general ergonomics and the weight of the spray gun will be checked.
In which case it is necessary to purchase pneumatic, and in what electric spray gun
The main points on which a choice will be made between an electric and a pneumatic spray gun:
In closed premises of the paint shop or directly in the painting chamber, the use of electrical equipment is prohibited.
There are electrical devices ahead of them, but at the expense of worse paint quality. If you need an excellent result of staining, then you have to put up with a colorful mist from a pneumatic spray gun.
Drawing of viscous paint.
The principle of the electric spray gun allows it to work with most types of paint and varnish, including those that have an increased viscosity. In this case, often they are equipped with nozzles with a diameter of 1.5 mm or higher, which are not suitable for working with liquid formulations - these paints will flow and be applied unevenly.
Replaceable nozzles and nozzles.
Most often household electric spray guns have a single nozzle that can not be replaced. This means that a particular spray gun will work with paints whose viscosity is within a certain range. It will be necessary to always bring paint materials to a certain consistency, otherwise some of them will flow, and others - to clog the nozzle.
The quality of the painting.
A pneumatic spray gun breaks the paint into as small particles as possible, which allows it to be applied with a thin layer even on the surface of a complex shape. Electric devices in this respect are losing much - the paint in them is not completely broken, so the applied layer is much thicker.
Based on these properties, it is clear that comparing pneumatic and electric spray guns is quite difficult - each of them will be good in its place. For home use, where there are no strict requirements for the thickness of the paint layer and other parameters, the more compact and versatile electrical devices are better suited.
For production it is already necessary to choose a pneumatic spray gun with its high quality of painting. Also, the "division of labor" is often used, applying an electric floor paint station for applying primers, and for the final painting - a pneumatic spray gun.