The management of whirlpool fan noise uses a soundproof cover to cover the high pressure blower and isolate it from the operator. This is an effective noise control method and can completely reduce the operating site noise to the allowable level.
The soundproof cover is mainly composed of a plate, a sound-absorbing material, a damping layer, and the like. The shell can be made of steel plates, hard aluminum plates and other denser plates. When the shell is made of thin steel plate, a layer of soft rubber or a layer of damping paint must be tightly adhered to the steel plate. The thickness of the damping coating should be greater than 2-3 times the thickness of the steel plate in order to suppress the vibration of the steel plate surface.
The inner wall of the soundproof sheet shall be lined with a 30-50mm thick sound-absorbing material, and the commonly used sound-absorbing materials are ultra-fine glass wool, porous foam or slag wool. In order to avoid the scattering of sound-absorbing material, a glass cloth may be covered outside the sound-absorbing material, and then a metal mesh or a perforated steel plate may be used as a protective layer. The aperture of the perforated steel plate is often taken as 3 mm, and the perforation rate is often taken as 20 to 30 percent. Finally, a metal bead or wire is attached to the wall.
The whirlpool fans and other equipment usually require heat dissipation. For this purpose, ventilation openings and air ducts are required for the cover. The inner wall of the air duct is usually made of polyurethane foam, and an air intake muffler is installed at the junction of the air duct and the cover to reduce the airflow for cooling and ventilation. Generated aerodynamic noise. And it is required that the muffler's noise reduction volume be similar to that of the sound insulation cover.
Acoustic enclosures require sealing, and lax seals will greatly reduce the effectiveness of sound insulation. Therefore, attention must be paid to the treatment of holes and gaps. When the mask wall has 1/100 area of ​​small holes, the sound insulation of the sound insulation cover will not exceed 20dB, and the gap of 2~3mm in length and 1m in length can also pass 10dB. Therefore, the holes and gaps must be filled with soft rubber. When the cover plate on the cover wall is closed, the compression mechanism must be used to fasten the compaction. When the pipe passes through the cover wall, it needs to be wrapped with a sounding sleeve. In general, the doors, observation windows, vents, and sound insulation sleeves on soundproof covers are all weak links. Measures should be taken to reduce the sound insulation volume so as not to affect the overall sound insulation effect.
The vibrations of the whirlpool fans and other equipment and their foundations must not be transmitted to the sound insulation layer. Rigid connections should be avoided as much as possible. Where the genus is at the junction and the crest support, an elastic material liner should be used. Also, the connection between the cover body and the air duct should be connected with a canvas or a serpentine pipe. The length of the connection part is generally 100 to 200 mm.
For ease of maintenance, the soundproof enclosure can be assembled from several components, that is, made into a movable type. When installing, pay attention to the elastic material between the joints of various parts, and use special components to clamp tightly to close the seal tightly.
2. Using sound barriers to control noise Applying sound barriers to reduce fan noise is to place the sound barrier between the fan unit and the operator. Its role in reducing noise is based on the principle of sound wave propagation (winding). In the noise propagation path, the acoustic wave is blocked by the barrier and diffracts at the edge of the barrier, thereby forming an acoustic shadow area behind the barrier, and the noise is reduced in this acoustic shadow area. The application of sound barriers reduces noise and does not require a hood or other enclosure to close the fan.
Sound barriers are easy to prepare and easy to install, which is a significant advantage. The sound barrier should be made into a unit type, the plane of which can be in the form of a plate shape, an L-shape, etc. The shape of the cross-section should be “concealer type†to provide the diffraction coefficient. Its structure is simple. Cold-formed thin-walled steel is used as the skeleton. A 0.8-1.50-mm thin steel plate is sandwiched between the two sides as a sound-insulating layer. The steel sheets on both sides of the steel plate are lined with 50-100mm ultra-fine glass wool as the sound-absorbing layer. The outer layer is clamped with a thin steel mesh. The width of the sound barrier should be slightly larger than the length of the fan unit under control. Each unit should be made of 0.6m, 0.8m or 1.0m, and it should be spliced ​​when installed. The seams between the unit bodies are connected by rubber sealing strips, and the bottom is fixed on the floor lined with latex sponge plastic layer by the steel bolts at the bottom.
If the conditions permit, the upper part of the building where the high-pressure fan unit is located, the floating cloud-type sound-absorbing board and the vertical sound-absorbing board will be set accordingly, and the noise control effect will be further improved. Application of sound barriers to control fan unit noise can generally be reduced 8? 12dB.
The soundproof cover is mainly composed of a plate, a sound-absorbing material, a damping layer, and the like. The shell can be made of steel plates, hard aluminum plates and other denser plates. When the shell is made of thin steel plate, a layer of soft rubber or a layer of damping paint must be tightly adhered to the steel plate. The thickness of the damping coating should be greater than 2-3 times the thickness of the steel plate in order to suppress the vibration of the steel plate surface.
The inner wall of the soundproof sheet shall be lined with a 30-50mm thick sound-absorbing material, and the commonly used sound-absorbing materials are ultra-fine glass wool, porous foam or slag wool. In order to avoid the scattering of sound-absorbing material, a glass cloth may be covered outside the sound-absorbing material, and then a metal mesh or a perforated steel plate may be used as a protective layer. The aperture of the perforated steel plate is often taken as 3 mm, and the perforation rate is often taken as 20 to 30 percent. Finally, a metal bead or wire is attached to the wall.
The whirlpool fans and other equipment usually require heat dissipation. For this purpose, ventilation openings and air ducts are required for the cover. The inner wall of the air duct is usually made of polyurethane foam, and an air intake muffler is installed at the junction of the air duct and the cover to reduce the airflow for cooling and ventilation. Generated aerodynamic noise. And it is required that the muffler's noise reduction volume be similar to that of the sound insulation cover.
Acoustic enclosures require sealing, and lax seals will greatly reduce the effectiveness of sound insulation. Therefore, attention must be paid to the treatment of holes and gaps. When the mask wall has 1/100 area of ​​small holes, the sound insulation of the sound insulation cover will not exceed 20dB, and the gap of 2~3mm in length and 1m in length can also pass 10dB. Therefore, the holes and gaps must be filled with soft rubber. When the cover plate on the cover wall is closed, the compression mechanism must be used to fasten the compaction. When the pipe passes through the cover wall, it needs to be wrapped with a sounding sleeve. In general, the doors, observation windows, vents, and sound insulation sleeves on soundproof covers are all weak links. Measures should be taken to reduce the sound insulation volume so as not to affect the overall sound insulation effect.
The vibrations of the whirlpool fans and other equipment and their foundations must not be transmitted to the sound insulation layer. Rigid connections should be avoided as much as possible. Where the genus is at the junction and the crest support, an elastic material liner should be used. Also, the connection between the cover body and the air duct should be connected with a canvas or a serpentine pipe. The length of the connection part is generally 100 to 200 mm.
For ease of maintenance, the soundproof enclosure can be assembled from several components, that is, made into a movable type. When installing, pay attention to the elastic material between the joints of various parts, and use special components to clamp tightly to close the seal tightly.
2. Using sound barriers to control noise Applying sound barriers to reduce fan noise is to place the sound barrier between the fan unit and the operator. Its role in reducing noise is based on the principle of sound wave propagation (winding). In the noise propagation path, the acoustic wave is blocked by the barrier and diffracts at the edge of the barrier, thereby forming an acoustic shadow area behind the barrier, and the noise is reduced in this acoustic shadow area. The application of sound barriers reduces noise and does not require a hood or other enclosure to close the fan.
Sound barriers are easy to prepare and easy to install, which is a significant advantage. The sound barrier should be made into a unit type, the plane of which can be in the form of a plate shape, an L-shape, etc. The shape of the cross-section should be “concealer type†to provide the diffraction coefficient. Its structure is simple. Cold-formed thin-walled steel is used as the skeleton. A 0.8-1.50-mm thin steel plate is sandwiched between the two sides as a sound-insulating layer. The steel sheets on both sides of the steel plate are lined with 50-100mm ultra-fine glass wool as the sound-absorbing layer. The outer layer is clamped with a thin steel mesh. The width of the sound barrier should be slightly larger than the length of the fan unit under control. Each unit should be made of 0.6m, 0.8m or 1.0m, and it should be spliced ​​when installed. The seams between the unit bodies are connected by rubber sealing strips, and the bottom is fixed on the floor lined with latex sponge plastic layer by the steel bolts at the bottom.
If the conditions permit, the upper part of the building where the high-pressure fan unit is located, the floating cloud-type sound-absorbing board and the vertical sound-absorbing board will be set accordingly, and the noise control effect will be further improved. Application of sound barriers to control fan unit noise can generally be reduced 8? 12dB.
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