The expensive system of mechanical ventilation of the house designed to provide the maximum level of comfort can become source of continuous tiresome noise at which it is necessary to forget about rest. Therefore it is necessary to provide effective noise isolation of air ducts on projecting phase.
The causes of noise in air ducts
Even low noise level can affect negatively work of nervous system, cause increase in tone of vessels what increase in arterial blood pressure results of. The irritating constant noise can even break metabolism, motility of intestines, to lead to dysfunctional frustration and to become the cause of constant insomnias. Therefore the noise isolation of air ducts is really necessary.
The operation of ventilating devices and the equipment arising at the same time or vibration various noise having irregular local character, which are formed as a result of emergence of turbulent streams in the system of air ducts can become the reason of uniform buzz of fans and periodically amplifying howling sound in pipes.
As a rule, as explanation for it serve those mistakes which have been made on projecting phase of vent system, including the wrong acoustic calculations. Those requirements for noise isolation which are imposed to the projected system have to be formulated in advance. Developers have to have the scheme of rooms of the house in which those rooms in which acoustic noise have to be minimum are specified. Taking into account it the ventilation equipment and the place of its installation, ways and technologies shumo- and vibration insulations, places and ways of laying of air ducts, their sizes and also types and the locations of branchings, knees and valves is chosen. It is possible to refer refusal of use of air ducts in the systems of recirculation of air when air streams freely circulate in space between overlappings and drop ceilings to typical mistakes which result is increase in noise. You should not save on such trifle as pipes of air ducts which, have been equipped with protecting covers, will allow to minimize such noise and will not worsen the general parameters of acoustic permeability of walls. To avoid undesirable noise in those rooms in which noise-insulating requirements are high the air ducts need to be laid over non-residential premises: storerooms, wardrobe rooms, bathrooms. When it is not possible to make it, in the project it is necessary to consider additional measures for protection against noise. Sometimes pipes of ventilation lay between adjacent living rooms while their conclusion in corridor and separate distributing to each room will be optimal variant. Plant louses of minimization of local noise it is necessary to use air ducts of big section in vent system. It allows to reduce the speed of air streams and to minimize turbulence.
Noise isolation of air ducts
To effective ways of reduction in sound level in ventilation systems the internal or external sound insulation of air ducts by means of special materials is: glass - and organic fiber, frothed polyethylene and rubber. Isolation of air ducts allows not to remove the noise cause, but to considerably reduce it in the functioning system. The materials having fibrous structure, such as fiber glass, are optimum for use for this purpose.
For the pipes and air ducts connected to the equipment with in the rotating or vibrating knots, it is necessary to use flexible connections.
Now in the market of insulating materials there were lamella-mats which characteristic is the cross arrangement of fibers. It allows to do when wrapping air ducts such mats without zalom and folds, to provide dense adherence of insulating material to surface of pipes. The soundproofing damping materials with which paste over air ducts and the equipment of system allow to reduce noise level by 7-15 DB, this indicator depends on noise range. Choosing optimum noise-insulating material, it is necessary to consider noise sound pressure level on octava strips, form and the size of section of pipes of air ducts. As a rule, the maximum effect can achieve only when all surface of the ventilation system is pasted over that guarantees lack of sound bridges through those its parts which have not been covered with insulating material. In these cases it is important to pick up correctly elements of fixture and to carefully close up passes through walls and overlappings zvuko- and noise-insulating materials.
The local aerodynamic noise provoked by turbulent air flows can be reduced, having installed the absorbing muffler.
For pipes of rectangular cross section the technology of pasting of their internal surfaces is used by the materials damping noise, it can be made in local areas where there is probability of emergence of aerodynamic noise. In this case the efficiency of noise isolation directly depends on the scheme of facing of air canals, places where interior panels are established.