Noise-blocking devices are installed in ventilation, so that the functioning of the system does not cause discomfort. The silencers are made of soundproof material and are used both in the exhaust, in the supply, and in the duct ventilation.

Principle of operation of the silencer

A silencer is a device with a large surface area, built into the ventilation and covered with sound-absorbing material. Use noise silencer begin when installed in a fan building, the work of which is accompanied by vibration, felt and audible even at a great distance. And this is absolutely natural, because air passes through the ventilation channels, resulting in oscillations or aerodynamic noise. In addition, the airing system of the room has another source of fairly loud sounds - the drive.

The muffler acts due to the location of the mesh inside it and a special sound-absorbing material.Rokot, produced by a fan, passes through a special matter and is absorbed. Therefore, the noise from the operation of the airing device of the room becomes extremely quiet.

Types of silencers

Devices that affect the noise level from the operation of the ventilation system are:

• plate (look like a box of metal with a slot for the passage of air, which is divided into compartments, covered with sound-absorbing matter);

  The device of the plate silencer differs in a complex construction

• tubular (created from two pipes, and in the one that is inside the device, many holes have been made that bring air to the soundproof material).

  Inside the tubular muffler is a pipe with a number of holes

Tubular silencers are divided into round and rectangular devices.Regardless of the shape, the details of the tubular muffler for ventilation are inserted into each other.

The outer element of this device is distinguished by a smooth surface, and the inner one - by a perforated cover. The dimensions of the pipe located in the central part of the device correspond to the ducting parameters into which the sound attenuator is immersed.

If the standard noise reduction devices are not able to function or are not suitable for a particular ventilation system, then one should think about installing a flexible silencer. This device is used in both apartments and public places.

The indicator of sound absorption of the device

On the possibility of a sound attenuator to absorb the sounds that accompany the work of ventilation, the following affects:

• dimensions of the device, standardized to the values ​​of 60, 90 and 120 cm;
• The thickness and location of the layer that isolates sounds;
• the speed of movement of air masses (noise is best absorbed when the gas moves slowly);
• The area occupied by the device (if it is close to the fan, it works well).

Requirements for installing a silencer

The location of the silencer is the area between the fan and the beginning of the duct. Sometimes the device is mounted in close proximity to air distributors or used in exhaust systems, where a special mechanism is responsible for air movement. In the latter case, it is customary to use two sound attenuators in the ventilation - before the fan and after it.

However, the most common place of installation of the muffler is behind the fan, at some distance from the air duct.It happens that the device for absorbing loud sounds is set further down the grilles of the ventilation system.

Sound attenuators are used to reduce the sounds that come from both the exhaust or supply and duct ventilation systems. How many devices will be needed to achieve silent operation of the fan depends on the scheme and length of the system for cooling air masses.

No need to install sound attenuators if there is a natural ventilation in the apartment.But in an exceptional situation, which may be the location of a house in a busy area, the ventilation system is still equipped with a device to reduce the level of sound vibrations. Thus, the home wants to get rid of sounds from outside, freely penetrating through the ventilation holes.

Mount silencer is prohibited when harmful gas is in the channels of the ventilation system, or rather, in the air itself.

Choosing a noise absorption device

Before going to the store behind the sound attenuator, you need to find out what is the loudness level of the sounds produced by the fan. Acoustic calculation, for which special equipment is used, will allow to determine the area and length of the device. When choosing a sound attenuator, you need to focus on the necessary noise reduction indicator, due to the loudness level of sounds within the permissible norm.

Tubular silencers are advised to purchase for ventilation, in which the duct cross-section is about 50 cm.And in a system with a larger channel size, it is more reasonable to mount a plate device.

To not regret buying a muffler for ventilation, you should purchase a device no longer than 2 m, because a larger size of the device will cause noise propagation by indirect ways. If necessary, mount a three-meter silencer, it is recommended to divide the device into 2 parts and To establish so that between them there was an interval in 80-100 sm, used for accommodation of the flexible insert in length 10-15 cm.

It is advisable to choose in favor of a silencer in which steel or vinyl plastic is used as the material with perforation, and the problem of sound absorption is assigned to thin fiberglass or cotton wool (treated with flame retardant, flame retardant, and antiseptic agents that stop processes decay).For exhaust air ducts it is better to purchase devices with mineral wool and fiberglass inside, and for supply - anything else, because in such a system of particles of cotton wool will scatter and fall into the room.

The efficiency of the silencer can be judged by such criteria as:

• type of sound-absorbing material;
• Type of resistance to blowing through the protective layer;
• the thickness of the plates and the distance between them (the larger the clearance, the worse the lamellar silencer is saved from noise);
• the length of the plates (the device with plates about 3 m works best);
• air flow velocity in the free section of the device (with increasing this parameter, the muffler functions worse).

Installing the silencer

Installation of the silencer requires the following:

1. Guided by acoustic measurements, connect the device to the air duct in the area where the ventilation produces the most noise.
2. If the muffler is round, then it is necessary to attach it with screws and two nipples in the part of the ventilation duct, into which the connecting flange is inserted.
3. When the device is rectangular, it should be mounted with bolts, steel corners and a clamp that tightens the two flange frames.
4. Be engaged in laying additional noise insulation, that is, glue the air duct with felt or wrap with mineral wool.
5. Install a coarse filter if solid inclusions are seen in the air masses of the ventilation.

Video: ventilation with soundproofed fan

Creating a silencer with your own hands

The silencer can be made with your own hands, refusing to buy an inexpensive device in the store.

If you manufacture the device yourself to absorb the sounds of the ventilation system, you will need the following tools:

• a fragment of a tube covered with a layer of zinc, with a diameter equal to the size of the ventilation duct;
• section of pipe, the caliber of which is 6 cm less than that indicated above;
• a heater, simultaneously acting as a soundproofing device (basalt wool 5 cm thick, glass wool or any other fiber treated with the product from ignition);
• clamps made of plastic;
• slate nail;
• riveting gun;
• pliers;
• a hammer.

To assemble the silencer, you must follow all the instructions in the instruction:

• in the first fragment of the galvanized pipe, having deviated from each edge of 10 cm, make a large number of holes using a nail and a hammer;
• Keep an eye on making a gap of 1 cm between the holes created;
• screw a layer of basalt material onto the perforated tube, leaving a distance of 8 cm on both sides of the product empty;

  The thickness of the soundproofed material must be 5 cm

• tighten the material absorbing noise by four clamps;
• having departed from one edge of a pipe of a larger diameter of 6 cm, draw a line along the circumference;
• to the planned line to make incisions, as if creating "petals
• all the resulting sheets are bent at right angles to the center, mark, retreating from the edges of 3 cm, and again press, but this time along the pipe at an angle of 90 degrees;
• insert the second metal product into the first (perforated), as a result of which the made "petals" will fasten the tubes to each other and will become the support for the insulator;

  In the design there is a zone for stuffing soundproof material

• cut according to the scenario described above and the second end of the combined pipes;
• Install the muffler in the duct, fixing the clamps;
• grease sealant all voids and joints.

  Perforated pipe is made of metal mesh

Video: how to install and make a sound attenuator for forced ventilation

The muffler will make the life of the owners of the apartment, where the ventilation system is installed, truly calm. The homemade device allows to reduce the noise level by 15 dB, which means that it works no worse than the industrial one.