The compressor is a device that compresses the air through an engine, accumulating it inside its steel tank. The air is then released from a pipe at a considerable speed, proportional to the pressure generated inside the compressor. The air that comes out can be used in different ways, and here lies the great usefulness and versatility of the compressor which finds a very wide use both among professionals and among DIY and DIY enthusiasts. Various compressor models can be found on the market, from the largest and most powerful ones intended for professional use to those with small dimensions and limited power which are usually kept in the cellar or garage at home. For example, portable compressors are very convenient, which can be transported wherever you need them and which are powered by a combustion engine; the fixed ones, however, are usually electrically powered. Another important classification in the large family of compressors concerns the volumetric ones, in which the compression is guaranteed by well-quantified mechanical movements, and the dynamic compressors, in which the compression is variable according to the rotation speed of a system of blades. Finally, there are also particular compressors that work "in reverse": instead of compressing the air they dilate it, decreasing the pressure and thus allowing vacuum to be generated.
Reciprocating volumetric compressor
In the DIY and do-it-yourself sector, the most used compressor by far is the reciprocating volumetric one, with electrical power supply. Seen from the outside, this compressor looks like a cylinder whose dimensions (volume) vary depending on the model. Inside this cylinder there is a piston which, by means of a connecting rod, is driven by the electric motor of the compressor. In the cylinder there are two passages whose opening and closing occurs alternately: thanks to the first hole the air is sucked in, while through the second the same air comes out, at a higher pressure than the inlet one. At the tank level there is a particular valve connected to a rubber hose, often spirally wound and very flexible and resistant. At the end of this tube there is a fitting on which various terminals can be applied and removed, depending on the needs of use. The most used are for example:
- spray gun;
- gun for unscrewing and tightening nuts;
- terminal for spraying steam;
- gun for inflating inner tubes (for example those of bicycles).
The pressure with which the air comes out can be modulated through a manual adjustment system. In this type of compressor, as in other types, there is a safety valve that allows excess pressure to be vented. This device resembles in some ways the valve of a pressure cooker, and is activated immediately when the internal pressure reaches excessive levels due to malfunctions or incorrect use of the compressor.
Here are some of the typical uses of the compressor:
- inflation : thanks to the compressor it is possible to connect the tube to the inner tube of a bicycle for example, inflating it in a few moments. Similarly, the compressor can be used to inflate air balloons, rubber swimming pools, dinghies or camping mats;
- cleaning : by connecting a special spray gun to the end of the hose it is possible to use the compressor to spray air, water or steam. In this way you can clean the car, railings or gates, sports equipment, mechanical tools, various surfaces and much more;
- unscrew and screw : in this case the pressure generated by the compressor is used to screw and unscrew nuts or bolts, exactly as happens with the gun used by tire dealers;
- use of terminals : for example, hacksaws, screwdrivers, nail guns, drills, chisels, staplers, staplers, airbrushes, grinders, sanders and a wide range of compatible equipment for both professional and domestic use can be connected to the air outlet pipe .
Maintenance and safety
The compressors found on the market are safe and certified devices, therefore the only problems can be caused by incorrect use, incompetence or failure to comply with some fundamental rules relating to safety and maintenance. First of all, the compressor must be placed in a place away from bad weather, not affected by temperature changes and possibly protected from excessive cold and heat. It is above all the plastic components, such as the rubber hose, which are negatively affected by non-optimal conservation and which therefore could deteriorate and crack prematurely. The environment must also be protected from dust (when not in use, it is advisable to cover the compressor with an old sheet) and humidity. As regards maintenance operations, these must be carried out with the machine turned off, disconnecting the power plug and discharging any residual air present in the compressor. Here is the periodic maintenance to be carried out:
- after the first 100 hours of use of a newly purchased compressor it is necessary to check the tightness of all screws, pipe connections and clamps;
- every 300 hours of use it is necessary to clean the suction filter on which, over time, dirt and foreign bodies deposit;
- every 500 hours the oil must be replaced. First it is necessary to drain the used oil through the drain cock, and then top up the tank with new oil. This operation must be carried out with the compressor hot; used oil must be taken to a specific collection center and never poured into sewers;
- every 500 hours you need to check the drive belt and in particular its tension. The compressor's instruction booklet contains the optimal values for this parameter;
- all the mechanical components of the compressor must be cleaned approximately every 6 months;
- every 2 years we recommend checking, cleaning and possibly replacing the delivery and suction valves.
Air compressor prices
On the market you can find compressors of different sizes, power, make and model which obviously differ greatly in terms of prices. A small compressor, around 25-30 litres, is usually placed in a price range of 100 to 200 euros. Even smaller and easier to handle are the 10-15 liter compressors, whose prices are generally around 50-100 euros. If you need a compressor of around 100 litres, you have to take into account an expense of around 400-500 euros, while large compressors, 200 liters or more, cost much more and are sold for no less of 700-800 euros. The choice of one or the other model depends primarily on the specific use for which the compressor is intended, and on its frequency of use. If you plan to use it occasionally and for simple jobs, such as inflating bicycle tires, it is not worth purchasing a powerful compressor which, in addition to being more expensive, is also more cumbersome. Precisely the issue of size must be carefully evaluated, since there is not always enough space in the cellar or garage to accommodate the bulkier models. Depending on the intended use, the compressor must have a certain output pressure. In this regard, it must be remembered that this parameter does not necessarily go hand in hand with the capacity of the compressor. To purchase a compressor you can go to a shop specializing in DIY and DIY, and usually in the stores of large chains (e.g. Brico Center, Castorama, Leroy Merlin…) it is possible to find compressors at discounted prices. Alternatively, an excellent channel for purchasing is the internet, where you can choose from a wide range of compressors often sold at competitive prices compared to those charged by physical stores. In the latter case, however, it must be remembered that shipping costs can also be in the order of several tens of euros, capable of significantly increasing the final price.
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