How to choose a compressor for a sandblasting machine

Sandblasting machines are widely used in everyday life, in construction, in many industries. They are designed to clean metal, concrete and a number of other materials from old coatings, dirt and rust. The compressor for sandblasting is an essential element of the system, the quality of the final result depends on its power and correct operation.

Content:

• Types of Compressors
• How to choose a sand blast blower
• main parameters
• What is more important: pressure or volume of air
• Screw or reciprocating compressor installation: what to choose
• Diesel, gasoline and electric supercharger
• Low temperature operation
• Which compressor lasts a long time?
• New or used compressors
• The right choice of hoses
• What is the best way to operate a compressor?
• Condensate neutralization
• Oil neutralization
• The operation of electric compressors in the winter
• Dust reduction in the inlet

Types of Compressors

A supercharger, or a compressor for a sandblasting apparatus, is a device for moving air flow under the action of high pressure, which promotes mixing of air and abrasive material, supplying the mixture to the treated surface. By type of power, compressors are:

• diesel;
• electric.

Depending on the design, there are two types of superchargers - piston and screw. The first move the air due to the reciprocating movements of the piston in the cylinder, have a fairly large performance. Secondly, 2 gears are used, which rotate in opposite directions and move the air flow.

How to choose a sand blast blower

A compressor is the most expensive element in a sandblast installation, so you need to buy it after a thorough assessment of all parameters. Many users buy low-cost devices to save money, but their specifications may be low. This leads to a significant decrease in the speed of the sandblast, an increase in the consumption of abrasive and an increase in cost.

main parameters

The most important technical characteristics of the compressor are the pressure that it is able to provide, and the level of consumption of compressed air. Also, when selecting a device, it is necessary to evaluate the consumption of abrasive material per unit area and the speed of processing.

What is more important: pressure or volume of air

When evaluating the performance of the compressor (the volume of air supplied per unit time and the pressure with which air is supplied to the nozzle), we can draw the following conclusion: both characteristics are important and determine the overall efficiency of the sandblast. Nevertheless, the quality of the air-abrasive mixture and the speed of grinding surfaces are more dependent on performance. If the volume of air per cubic meter. m / min will be significant, you can use larger nozzles, which will also accelerate the operation of the sandblasting apparatus. For most sandblasting models, compressors with a capacity of 2.2-17 cubic meters are used. m / min

When the supercharger is selected according to the pressure indicator, surface characteristics must be taken into account. Here are the necessary pressures and the most common materials that have to be processed:

• stone, brick, concrete - 3-5 bar;
• metal - 5–8 bar;
• thick-layer, abrasion-resistant coatings - 9–12 bar;
• any materials processed from a distance of more than 60 meters - 9-12 bar.

In the sleeve for feeding the abrasive, the working pressure is reduced, and losses are reduced by choosing the hose as short as possible. The reduced distance is covered by increasing the compressed air hose.

Screw or reciprocating compressor installation: what to choose

Piston blowers are much less commonly used for sandblasting machines. Their productivity is quite high, but the air is usually supplied with jerks, with pulsation, so the abrasive can collect in lumps. As a result, the pressure drops, the nozzle ejects the air-sand mixture unevenly. To eliminate this problem, you have to install a receiver (air collector).

Another unpleasant feature of piston blowers is the appearance of water-oil condensate, which provokes clumping of the abrasive, and sometimes the failure of the entire installation. Due to the high degree of removal of compressor oil, such devices are less in demand when sandblasting materials.

Screw compressors are common in this industry, devoid of these shortcomings. Instead of pistons, they have two worm gears that rotate in opposite directions. The advantages of such devices:

• long continuous work;
• air supply with slight pressure drops;
• profitability of operation and maintenance;
• low rate of vibration;
• lack of pushes of air and clumping of an abrasive;
• very quiet operation due to low noise level.

Diesel, gasoline and electric supercharger

Sandblasting units can be equipped with diesel or electric motors. The advantages and disadvantages of devices, as well as the final choice, are influenced by many factors. A modern diesel compressor is a powerful unit whose operation does not depend on the connection to the mains. Most models are equipped with a performance adjustment system: when air consumption decreases, the speed of the drive motor is automatically reduced, and vice versa.

The main advantages of gasoline superchargers are mobility and autonomy. If it is not possible to connect the device to the network, the use of gasoline compressors is sometimes the only possibility of sandblasting. If there is a desire to collect sandblasting yourself, it is worth paying attention to just such devices. However, due to the high fuel price, the use of electric compressors is cheaper, and the rationality of diesel operation is not always observed. Also, at temperatures below +5 degrees, it will be necessary to additionally equip the preheating and cold start installation - without them, the supercharger will not work.

Electric compressors are considered the most economical, they are simpler in design features, operation and maintenance. Good devices have power from 22 to 100 kW, but not every power supply can withstand their connection. For off-site use, there are mobile systems on the chassis for sale.

Low temperature operation

If you have to use the compressor in the winter, you should take care to prevent the formation of moisture-oil condensate and its concentration in the system. Otherwise, there is a high risk of reduced unit performance and surface cleaning quality, as well as compressor damage.

When using the device in the cold season, it is worth purchasing “winter” oil instead of “summer" oil. The pour point of such a liquid is about –25 degrees, so the device will work normally, without failures. Equipping the supercharger with a pre-heater and a cold start system will also help prevent problems during frosts.

Which compressor lasts a long time?

When carrying out sandblasting, a lot of dust appears, especially when using ordinary (river) sand.This dust consists of broken abrasive particles, which are harmful not only to humans, but also to the compressor itself. Its penetration into the screw blocks reduces the life of the device, so cleaning surfaces is a long distance.

Some compressor models are equipped with additional filters, which seriously increases the life of screw blocks. Such installations are more expensive, but will last much longer. It is better to buy a compressor for a sandblast of a well-known brand, which has service centers, and spare parts for devices are sold in the distribution network.

New or used compressors

Most manufacturers guarantee trouble-free operation of the superchargers for 7–10 years, after which their resource is exhausted. When purchasing a device that was already in use, you need to keep these terms in mind. The seller can show the technical documentation, which indicates the main parameters of the compressor, but these numbers are often lower in reality. The reason is the natural deterioration of equipment, a decrease in its efficiency. Only carrying out diagnostics using a flow meter will allow you to know the real picture.

For diesel compressors, fuel consumption increases seriously after 3 years of active use. The financial costs of operating such a device will be significantly higher, as well as the costs of possible repairs, maintenance. Any compressors older than 10 years are a waste of money, you should not buy them at all. They can break down when sandblasting is performed, moreover, repair is most often impractical due to its cost. When planning a large amount of work, you do not need to consider the option of buying used equipment, and for one-time polishing, you can look for a compressor for little money, but not too old to produce.

The right choice of hoses

The compressor equipment is of great importance for its efficient operation. This category includes fittings, adapters. The length of the hose from the compressor to the sandblasting nozzle should not be large, which must be taken into account when buying. It is recommended to purchase an additional hose and “build up” the one that goes from the installation to the unit for mixing air and sand: this will compensate for the lack of length.

In order for the compressor to work optimally, you need to follow these points:

• exclude a decrease in the diameter of the hoses (the indicator should be 3-4 times larger than the size of the nozzle);
• Minimize the number of joints and joints;
• Use only strong, reinforced hoses.

What is the best way to operate a compressor?

In order for the supercharger to serve for a long time and in good condition, it is necessary to monitor compliance with a number of conditions. The master must reduce the amount of dust that falls into the installation, or even eliminate such a phenomenon. Use the compressor only in acceptable weather conditions, depending on the manufacturer's recommendations. You will also have to take measures against condensation and damage to the compressor during winter operation.

Condensate neutralization

Condensate appears at the pressure conversion boundary during air intake and compression. After droplets of water get into the output tract, an abrasive clumps, which provokes the consequences:

• disrupts the operation of the unit;
• reduces the quality of grinding surfaces;
• causes corrosion of metal parts;
• reduces the number of reuse cycles of an abrasive;
• increases costs;
• may cause sandblasting damage.

High-quality installations are equipped with cyclone separators-dehumidifiers (water-oil separators). They are placed at the outlet of the supercharger and help to remove the condensed liquid, although they are not able to prevent its formation in the future.To neutralize the condensate and prevent its formation, you can use compressed gas coolers, coalescence filters, but refrigerated dryers are considered the most effective.

Oil neutralization

Most often, the appearance of oil in the outlet air stream is inherent in reciprocating compressors. It, like water, acts on the abrasive mixture and the installation itself is negative: it causes the appearance of condensate, which provokes clumping of the abrasive. The only difference is that water-oil condensate causes corrosion of parts, and purely oil condensate does not. However, the consequences of its action can be no less unpleasant:

• reduction in processing quality;
• destruction of the abrasive, a change in its properties.

To prevent such problems, a special oil trap is installed at the compressor outlet, and it is better to use combined installations with the possibility of “capture” and water condensate.

The operation of electric compressors in the winter

If the ambient temperature drops below 0 degrees, this can damage the operation of electric compressors. Starting an internal combustion engine at such temperatures is difficult. Therefore, when working with sandblasting in winter, you will have to take certain measures.

The case of the electric compressor must contain a heating device. You can do it yourself using a heating cable and a temperature sensor. Nevertheless, in order to avoid dangerous consequences, it is better to buy a compressor that is already equipped with a package for winter start-up.

Dust reduction in the inlet

To reduce the risk of dust from crumbling abrasive entering the compressor, the following steps can be taken:

• to the station where the receiver and supercharger are a single system, bring the hose and bring its end far beyond the workplace;
• in the device where the receiver and compressor are separated, extend the hose going from the supercharger and place it away from the working area.

Another option to prevent damage to the compressor from dust is to use a car or industrial air filter, which will need to be cleaned and replaced regularly. This will guarantee the reliable and trouble-free operation of the device over time.