Intensive development of industry contributes to a change in the conditions for the organization of labor of enterprise employees. With regard to manufacturing, we can talk about the problems of air purification, which is polluted by the smallest particles of waste. The tasks of aspiration for woodworking are especially acute, since it may not just be about chips and sawdust. Almost every enterprise of this type emits wood dust during mechanical processing, which poses a danger to lungs due to its adsorption capacity.
Aspiration as a type of pneumatic conveying systems
According to technical requirements, all woodworking enterprises have in-house or inter-workshop vehicles in their communication infrastructure. We are talking about pneumatic transport channels, which can be provided by traction bodies, drive systems or autonomous sources of energy supply. Aspiration systems just relate to such units, performing the tasks of timely removal of the aforementioned dust and chips in workshops where woodworking equipment is used. Aspiration as such is a complex of technical means and stationary communications, and requirements for it are presented on the basis of regulatory sanitary and hygienic regulations.
Varieties of suction systems
The configuration of the suction devices may vary depending on the conditions of use and technological requirements. The most common types of aspiration for woodworking:
- Directly centralized. Several channels from different woodworking machines collect the dust-air mixture in one stream and direct it to a separation apparatus, where air is separated from mechanical impurities. Clean air is sent to the atmosphere, and solid particles are sent to special dust collectors.
- Recycled centralized. The principle of operation is generally similar to the previous system, but with the difference that the purified air is not thrown out, but is transported to the workshop. This filtration scheme has advantages, since the temperature regime is maintained, however, the return of the processed air negatively affects the quality of updating the local air environment.
- Direct-flow autonomous. If in previous cases the contaminated flows are collected in one channel and subjected to general cleaning, then in the direct-flow systems for each machine there is an individual filtering apparatus that releases air into the atmosphere.
Ventilation systems
Direct-flow aspiration systems work in parallel with the supply and exhaust type ventilation . This combination is used when purified air is released into the atmosphere. Moreover, the task of ventilation is not only to update the air filling, but also to improve other microclimatic indicators inside the workshop. These may be characteristics of pressure, temperature and humidity. If the woodworking suction hoses work according to the recirculation principle with flow return, the supply and exhaust system performs the task of passive background cleaning. The fact is that recirculation in any case does not give a 100% removal of contaminants and the returned air will contain harmful mechanical impurities by 1-3% - about 6 mg / m In this case, the ventilation function is just useful, which regularly refreshes the air environment, eliminating the remnants of woodworking products. Once again, it is worth emphasizing the effects of improving the microclimate with increasing humidity and stabilizing the pressure.
Ducts in the suction infrastructure
Both the operation of the suction equipment and the provision of ventilation functions require a duct network. Industrial pneumatic transport is usually served by pipelines with a circular cross-section and a throughput of about 23 m / s. As for the manufacturing material, galvanized metal, metal-plastic and plastic composite structures can be used. The choice of material depends on the operating conditions at a particular enterprise. By design, the air ducts for aspiration of woodworking can be divided into spiral and longitudinal with flange and welded joints. The type of fastening and formation of joints affects the loss coefficient, which is important from the point of view of the tightness of the content of contaminated streams. According to the leakage coefficient, three categories of ducts are distinguished:
- The lowest class is 1.3 (l / s) / m.
- Middle class - 0.4 (l / s) / m.
- The highest class - 0.15 (l / s) / m.
The diameter of the channels varies from 140 to 1250 mm. Accordingly, the choice for this indicator depends on the original process pipes. The large format is used for supply and exhaust ventilation, and the small one is used for general dust and chip collection channels from machine tools.
Wood dust collection systems
In addition to transporting contaminated and clean streams, an important role is also played by the tasks of direct air purification. For this, cyclones and filtration systems are used. The first consists of two cylinders with an annular intermediate space, where the transition of clean air from dirty air is carried out. Once in the cyclone, the air-material mixture begins to rotate, during which solid particles up to 10 microns in size are sent to the discharge opening. Woodworking suction filters also separate dust from air. Corrugated cassette and fabric devices are used in the form of bags, sleeves and canvases. Both types of filters effectively work with fine dry pollution. The cleaning ratio reaches 99%.
Stationary shop systems of aspiration
To work with large volumes of material-air mixtures, recirculation workshop units are used that dump accumulated waste into special storage bins. The productivity of such equipment varies from 20,000 to 100,000 m 3 / h, and the capacity of the dust collector reaches 70 m3. The main operational advantage of the workshop suction systems for woodworking is their external placement and the possibility of organizing cleaning without the use of air ducts.
Homemade Aspiration System
In the household economy for the workshop, you can limit yourself to arranging powerful forced ventilation. When working with one tool or machine, a point dust collecting machine with a dust collector is enough. But professional aspiration for woodworking with your own hands can be realized only by the type of a full-fledged chip pump, which will also capture large particles. This design can be implemented on the basis of an asynchronous four-phase motor, which drives a powerful fan unit. From materials, it is necessary to provide thick chipboard panels for construction, a set of membranes of different calibers for multi-stage cleaning of flows, and plastic pipes through which flows will be circulated.
Conclusion
A high-quality dust collection and air purification system cannot be dispensed with even in the small conditions of a carpentry workshop. If we talk about specialized plants, then the aspiration system for woodworking BU can cost about 20-25 thousand rubles. It will be an analogue of an industrial cyclone or ventilation dust collector with a powerful engine. Comprehensive provision of the workshop with new equipment with air ducts and intermediate filters can cost about 100-150 thousand rubles.