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The compressors intended for production of stream of compressed air — very widespread type of the equipment. They are used both in the industry, and in construction, and in life. Different types of the compressor equipment, at the same time the most widespread types of compressors — piston are presented at the market (coaxial or with the belt drive) and screw — can be both oil, and oil-free. What do they differ from each other in what shortcomings and advantages oil and oil-free compressors from them it is better for them to prefer have?
The most widespread types of compressors
The compressor equipment can be different in scale and on design — beginning from the small devices which are used for pumping of tires and finishing with the large-scale plants of huge power which are used, for example, in the mining industry or on elevator installations. Compressors and for providing the pneumotool with compressed air are widely used. Repair and painting work, replacement of road surfacing, sandblast cleaning of facades of buildings — all this is made with their help.
It is possible to carry to the most widespread types of compressors screw (rotor) and piston.
In screw forcing and compression of air is made by screw pair — two screws with the wide blades rotating towards each other. Compressors of this kind can have very small sizes, they are economic in operation, are capable to long continuous operation and can provide equal, constant air stream.
Piston compressors work on all to the known principle of the pump: the movement of the piston reduces the volume of air chamber, as provides compression. It is the oldest kind of the compressor equipment: the first plant based on this principle was created by the inventor of the steam-engine Ivan Polzunov in the second half of the 18th century. However simplicity of design, reliability and non-failure operation of piston compressors has provided them popularity for ages. Coaxial installations belong to this type of compressors (piston with the direct drive). They are very compact, mobile, simple, and rather small power at the same time is quite enough for providing the household pneumotool with compressed air — guns for tires, small hammers or nut wrenches, airbrushes, etc. Therefore in house conditions or in small workshops coaxial compressors are most often used.
Oil and oil-free compressors: in what distinction
Screw and piston compressors can be as oil (they are also called maslozapolnenny), and oil-free.
In maslozapolnenny compressors for lubricant of the parts moving and rubbing the friend about the friend (including the piston or screws) compressor oil — mineral or organic is used. It envelops mechanism parts, creating on them thin film cover that allows to prevent abrasion of moving parts, having prolonged equipment life cycle. Besides, oil still promotes heat extraction, helping cooling of the unit. At the same time the air coming to the compressor directly contacts to lubricating stuff, and particles of oil "enrich" air stream. Subsequently air passes through oil filters (separators) where there is office of impurity. Extent of purification of compressed air depends on characteristics of the filtering system, however completely it is not possible to get rid of oil particles in most cases.
The principle of operation of oil-free compressors — same, as well as at oil. It is impossible to tell that in these models lubricant is not used at all: as a rule, oil after all is filled in in the unit, but comes to the special system of cleaning, at the same time channels on which it follows, are not crossed in any way with channels on which there is air stream. Piston or screw part works for them dry, or water acts as the greasing material. In the first case the device is called the compressor of dry compression, in the second — water filled.
For production of the parts which are exposed to friction usually high-strength materials not subject to wear and abrasion are used. As a result "at the exit" it is possible to receive compressed air of high quality without oil impurity. But the lack of lubricant worsens cooling, respectively such compressors heat up much quicker — and it is required by it to time for cooling much more.
Thus, both options have both advantages, and shortcomings. Let's consider them in more detail.
Maslozapolenny compressors: advantages and shortcomings
It is possible to carry to pluses of maslozapolnenny compressors:
- much bigger in comparison with oil-free working resource;
- possibility of long operation without overheating;
- the increased performance;
- smaller energy consumption;
- the best protection of parts against corrosion.
At the same time the main minus of such equipment is obvious: this availability of impurity of oil in air stream, reducing quality of compressed air. It significantly limits range of use of maslozapolnenny compressors and does not allow to use them for supply with compressed air of the "sensitive" pneumotool.
Powerful commercial oil compressors sometimes use in tandem with special installations for purification of compressed air. It allows to unite the high performance and high quality of air stream — however, naturally, it considerably increases the total cost of the compressor unit, complexity of its mounting and service. In life, in garage or in small workshop use of the special equipment for purification of compressed air, as a rule, is unjustified.
Pluses and minuses of oil-free compressors
It is possible to carry to undoubted advantages of oil-free compressors:
- high quality of the compressed air which is not containing oil impurity;
- the simplified service and economy on lubricating stuffs (lubricant in such units is changed less often, there is no need and to watch condition of oil filters).
The lack of oil in air stream allows to use such equipment in situations when it is necessary to provide the maximum purity of compressed air and also for connection of the pneumotool exacting to quality of air stream.
But at the same time such compressors are less durable and are not calculated on long working sessions therefore are not suitable for intensive use "without pauses", and energy consumption at them is significantly higher.
The choice of the compressor taking into account features of operation
Thus, it is better to acquire the answer to question of what compressor — oil or oil-free, depends first of all on tasks for which solution the equipment will be used. If the emphasis needs to be placed on purity of air stream — the oil-free compressor will be the best decision.
Such equipment is most often installed at the enterprises where special requirements to "purity of production" — pharmaceutical are imposed, chemical, food, by production of high-precision electronics; and medical institutions and dental offices. In life and small workshops oil-free compressors are most often used for air supply on airbrushes (air brushes).
If in priority — intensive use, durability and fault tolerance, then it is worth preferring the maslozapolnenny compressor. In case it is necessary to receive clean and at the same time continuous air stream, it is necessary to pay attention to oil compressors from the filtration improved by system.