**Technical Guidelines for Comprehensive Noise Control of Roots Blowers**
The noise of Roots blower can usually reach 75-95dB (A), and systematic noise reduction measures need to be taken. The following are treatment plans for different noise sources.
**1、 Analysis of Noise Sources in Roots Blowers**
|Noise type | Frequency characteristics | Sound pressure level (dB) | Main propagation path|
|----------------|---------------|-----------|------------------|
|Intake/exhaust noise | Medium low frequency (63-500Hz) | 85-95 | Air propagation|
|Mechanical vibration noise | High frequency (500-4kHz) | 80-90 | Structural sound transmission|
|Electromagnetic noise of motor | High frequency (1k-8kHz) | 75-85 | Air+structure propagation|
**2、 Technical measures for noise control**
**1. Silencing treatment (aerodynamic noise control)**
**(1) Selection of intake muffler**
-* * Resistance muffler * *: for 63-250Hz low-frequency noise (insertion loss 15-20dB)
-* * Composite muffler * *: Impedance combination type (broadband noise reduction 20-25dB)
-* * Special Requirements * *:
-Waterproof type: equipped with a hydrophobic filter layer
-Explosion proof type: stainless steel shell+flame-retardant filler
**(2) Design of exhaust muffler**
-Expansion and pressure reduction type: pressure loss<3kPa
-* * Parameter Example * *:
```markdown
Model: XZQ-200
Applicable air volume: 50m3/min
Noise reduction level: 22dB (A)
Pressure loss: 2.8kPa
```
**2. Sound insulation treatment**
**(1) Key points of soundproof enclosure design**
|Parameters | Standard Requirements | Implementation Cases|
|----------------|----------------------|----------------------|
|Sound insulation | ≥ 25dB (A) | 2mm steel plate+50mm centrifugal glass wool|
|Heat dissipation requirements | Ventilation rate ≥ 20 times/hour | Low noise axial flow fan (≤ 65dB)|
|Inspection door | Dual channel sealing structure | Maze type rubber strip seal|
**(2) Modular soundproof room**
-* * Assembled structure * *: 100 × 100mm steel frame+composite soundproof board
-* * Performance indicators * *:
-Sound insulation: 30-35dB (A)
-Weather resistance: IP54 protection level
**3. Vibration reduction treatment**
**(1) Vibration control level**
|Vibration standard | Allowable speed (mm/s) | Applicable scenarios|
|----------------|---------------|-------------------|
|ISO10816-3 | ≤ 4.5 | Conventional Industry|
|GB/T 6075.3 | ≤ 2.8 | Precision Equipment Periphery|
**(2) Vibration reduction system configuration**
-* * Basic vibration reduction * *:
-Rubber shock absorber pad: static compression capacity of 5-8mm
-Damping spring shock absorber: natural frequency 3-5 Hz
-Pipeline vibration reduction:
-Rubber flexible joint: pressure resistance of 1.6MPa
-Elastic hanger: isolation efficiency ≥ 80
**4. Supporting noise reduction measures**
-* * Silencing duct * *: lined with porous sound-absorbing material (perforation rate of 20-30)
-* * Sound barrier * *: Height ≥ 1.2 times the height of the equipment
-* * Greening noise reduction * *: Additional noise reduction of 3-5dB (A) for a 10m wide tree forest belt
**3、 Case study of noise control project**
**Case 1: Aeration fan room in sewage treatment plant**
-Before governance: 92dB (A)
-* * Measures * *:
1. Impedance composite muffler (imported)
2. Overall soundproof enclosure (28dB sound insulation)
3. Floating ground+spring damper
-* * After treatment * *: 65dB (A) during the day, in compliance with the "Industrial Enterprise Boundary Environmental Noise Emission Standards"
**Case 2: Explosion proof Roots blower for chemical plants**
-* * Special Requirements * *:
-Explosion proof grade: Ex d Ⅱ BT4
-Corrosion resistance: 316L stainless steel silencing element
-* * Solution * *:
-Resistive explosion-proof muffler
-Positive pressure ventilation soundproof hood
**4、 Prediction method for noise reduction effect**
**1. Calculation of sound pressure level superposition**
\[
L_{total} = 10\lg\left(10^{L_1/10} + 10^{L_2/10}\right)
\]
-Example: 90dB device+85dB device=90.4dB
**2. Insert loss estimation**
\[
IL = 10\lg\left(\frac{W_1}{W_2}\right)
\]
-Typical IL value of muffler: 15-25dB
**5、 Key points of maintenance management**
1. * * Muffler * *: Clean the internal dust accumulation every quarter (it needs to be cleaned immediately when the pressure difference is greater than 1.5kPa)
2. * * Sound insulation cover * *: Check the aging condition of the sealing strip every month
3. * * Shock absorber * *: If the static compression change measured annually exceeds 10, it needs to be replaced
**6、 Economic analysis**
|Measures | Investment cost (10000 yuan) | Noise reduction effect (dB) | Investment payback period (years)|
|----------------|--------------|-------------|--------------|
|Muffler | 2-5 | 15-20 | 1-2|
|Soundproof enclosure | 8-15 | 25-30 | 3-5|
|Comprehensive governance | 20-50 | 30-35 | 4-7|
**Practical suggestion * *:
-Priority should be given to using low-noise models (such as magnetic levitation fans) for new projects
-Recommended combination scheme of "noise reduction+sound insulation+vibration reduction" for renovation project
-5dB margin needs to be reserved in sensitive areas
Note: The specific plan needs to be developed in conjunction with on-site noise spectrum analysis. It is recommended to entrust a professional acoustic institution for testing and diagnosis.
