The noise control of Roots blower requires multi-level comprehensive treatment, combined with muffler, sound insulation, vibration reduction and other means. The following is a systematic noise reduction plan and implementation details:
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**1、 Noise source analysis**
The noise of Roots blower is mainly composed of three parts:
1. * * Aerodynamic noise * * (dominant, 85-110dB (A))
-Intake/exhaust pulsation (low frequency 125-500Hz)
-Airflow turbulence (medium high frequency 1k-4kHz)
2. * * Mechanical noise * * (70-90dB (A))
-Gear meshing (500-2kHz)
-Bearing vibration (high frequency)
3. * * Structural sound transmission * * (through basic propagation)
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**2、 Silencing technology solution**
**1. Silencer (core measure)**
-* * Intake muffler**
-Type: Resistance expansion chamber+Resistance sound absorption composite type
-Noise reduction level: 15-25dB (A)
-Key parameters: Diameter ≥ 1.2 times the pipe diameter, pressure loss<2kPa
-* * Exhaust muffler**
-Type: Maze or multi-stage expansion chamber
-Special Design:
-High temperature resistant structure (≤ 150 ℃)
-Anti corrosion coating (for treating humid and hot exhaust gases)
**Installation points * *:
-The distance between the muffler and the fan outlet is ≤ 1.5 times the pipe diameter
-Add rubber gaskets between flanges (to prevent vibration and sound transmission)
**2. Soundproof enclosure (for mechanical noise)**
-* * Structural Design * *:
-Outer layer: 1.5mm galvanized steel plate (damping layer+sound-absorbing cotton)
-Inner layer: 50mm thick rock wool (density 80kg/m3)
-Sound insulation: ≥ 20dB(A)
-* * Functional Design * *:
-Inspection door: magnetic suction seal+observation window (5mm tempered glass)
-Cooling system: Axial flow fan+silencing duct (temperature controlled start stop)
**3. Pipeline noise reduction**
-* * Soft Connection * *:
-Import/export rubber hose (length ≥ 10 times pipe diameter)
-Pressure rating matching (0.6-1.0MPa)
-Package Handling:
-Pipeline wrapped with aluminum foil and glass wool (thickness 30mm)
-Surface fixed with perforated aluminum plate (perforation rate>20)
**4. Vibration reduction measures**
-* * Basic vibration isolation * *:
-Install shock absorbers (damping springs or rubber isolation pads)
-Vibration transmission rate<5 (frequency ratio>3)
-* * Dynamic balance correction * *:
-Residual unbalance of rotor ≤ 1.0g · mm/kg (ISO 1940 standard)
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**3、 Special working condition solution**
|* * Problem * * | * * Countermeasure * * | * * Implementation Case * *|
|------------------|-----------------------------------------|----------------------------------|
|High frequency whistling | Installation of Helmholtz resonator (for specific frequencies) | 630Hz noise reduction of 12dB in a chemical plant|
|Wet gas corrosion | Muffler inner wall sprayed with PTFE+stainless steel drain valve | Sewage treatment plant extends service life to 8 years|
|Ultra low noise requirements | Secondary silencing series (expansion chamber+resistive silencer) | Hospital central gas supply system achieves ≤ 65dB (A)|
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**4、 Selection Calculation Example**
**Given conditions * *:
-Fan model: -150, flow rate 20m3/min, outlet noise 98dB (A)
-Goal: ≤ 75dB (A) at a distance of 1m from the device
**Design steps * *:
1. * * Muffler selection * *:
-Choose a composite muffler (with a noise reduction of 25dB), and the outlet noise should be around 98-25=73dB
2. * * Sound insulation cover supplement * *:
-The sound insulation of the enclosure is 20dB, and the mechanical noise is 90-20=70dB
3. * * Comprehensive effect * *:
-The total sound pressure level after superposition is approximately 75dB (meets the requirements)
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**5、 Maintenance and monitoring**
1. * * Daily check * *:
-Clean the intake filter of the muffler every month (replace it when the pressure difference is greater than 500Pa)
-Check the aging condition of the sealing strip of the soundproof cover every quarter
2. * * Performance Verification * *:
-Measure the noise at a distance of 1m using a sound level meter according to GB/T 3768 standard
3. * * Life management * *:
-Acoustic cotton is replaced every 3 years (shortened to 1 year in humid environments)
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**6、 Cost estimation**
|* * Measures * * | Initial investment (10000 yuan) | Noise reduction effect | Applicable scenarios|
|------------------|---------------|----------------|---------------------|
|Silencer | 0.8-2.5 | 15-25dB (A) | All Roots blowers|
|Soundproof enclosure | 1.5-3.0 | 15-20dB (A) | Indoor high demand places|
|System wide renovation | 4.0-8.0 | 30-40dB (A) | Sensitive areas such as hospitals and laboratories|
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**7、 Common Error Avoidance**
1. * * Muffler too small * *: Causes airflow velocity>25m/s, resulting in increased regenerative noise
2. * * Neglecting vibration reduction * *: Only silencing without vibration isolation, structural sound transmission causes overall noise reduction failure
3. * * Material Error * *: Ordinary glass wool (ceramic fiber should be selected) is used in high-temperature environments
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Through the triple scheme of * * muffler+soundproof cover+vibration reduction * *, the noise of Roots blower can be reduced from 90-100dB (A) to 65-75dB (A). For sensitive environments, it is recommended to add soundproof tunnels or use low-noise alternative equipment such as magnetic levitation fans.
