Code of practice for noise reduction in industrial buildings

IS 3483: Scope Key Points & Tables

Scope (Clause 2.0)

• Defines terms and establishes the basis for noise control in industrial environments.
• Aligns with international standards and Indian practices.
• Values and test results should be rounded per IS:2-1960.

Sound Absorption (Appendix B, Clause 10.2)

Notes

• d (thickness) typically 5 to 7.5 cm; larger for frequencies < 300 c/s.
• Absorption coefficients >1 indicate enhanced absorption due to shape (e.g., pyramidal).
• Noise reduction coefficient (NRC) is average absorption between 250-2000 Hz.

This provides the essential scope and absorption data for noise control per IS 3483.

IS 3483: Definitions, Terminology, and Key Tables

Key Definitions (Clause 2.0)

• The standard defines terms related to industrial noise control, sound absorbers, and noise reduction coefficients.
• All terms align with international standards and Indian practices.

Sound Absorption Coefficient (Appendix B, Clause 10.2)

Notes:

• d (distance parameter) usually ranges

IS 3483: Nature and Sources of Industrial Noise - Key Points

1. Noise Sources & Levels (Clause 7.1, Appendix A)

• Noise varies by operation; typical levels at operator positions are in Appendix A.
• Examples:
  • Drop forge hammer: High noise, detailed in Fig.1.
  • Textile weaving/spinning: Fig.2 shows frequency bands.
  • Carding/blowing processes: Fig.3.
  • Pneumatic tools: Fig.4.

2. Sound Pressure Level (SPL)

• Reference pressure: 0.0002 dyne/cm².

• SPL in decibels (dB) calculated as:

  [ L_p = 20 \log_{10} \left(\frac{p}{p_0}\right) ]

  where ( p ) = measured sound pressure, ( p_0 = 0.0002 ) dyne/cm².

3. Noise Exposure & Hearing Protection (Clause 9.2, Figs. 5 & 6)

• Noise reduction by layout: Offices separated from noisy areas; heavy walls with minimal openings.
• Hearing protection essential depending on exposure time & noise level:

• For every halving of exposure time, permissible noise increases by ~3 dB.

4. Noise Control Recommendations

• Use layout segregation.
• Apply hearing conservation measures if noise exceeds curves in Fig.5 & 6.
• Employ ear protection devices as per exposure.

graph LR
A[Industrial Noise Sources]
A --> B[Drop Forge Hammer]
A --> C[Textile Weaving & Spinning]
A --> D[Carding & Blowing]
A --> E[Pneumatic Tools]

F[Noise Control Measures]
F --> G[Layout Segregation]
F --> H[Heavy Walls]
F --> I[Hearing Protection]

B & C & D & E --> J[Noise Levels at Operator]
J --> K[Exposure Limits & Protection]
K

IS 3483: Measurement of Noise Levels - Key Points

1. Noise Level Measurement

• Reference Sound Pressure Level: 0.0002 dyne/cm².
• Typical measurement distance (d): 5 to 7.5 cm; larger for frequencies < 300 c/s.

2. Noise Levels for Industrial Operations (Clause 7.5 & Appendix A)

• Noise levels vary by operation; see typical spectra in Figures 1-4.
• Example: Hammering, riveting, textile mills, pneumatic tools.

3. Absorption Coefficients (Appendix B, Clause 10.2)

4. Noise Reduction by Layout (Clause 9.2)

• Separate office from production areas.
• Avoid common walls; if unavoidable, use heavy walls with minimal openings.

5. Noise Exposure Criteria (Fig. 5 & 6)

• Ear protection recommended when noise exceeds specific decibel levels depending on exposure duration.
• Exposure-time vs. permissible noise level relation: halving exposure time allows ~3 dB higher noise.

Formula for Noise Level in Decibels (dB):

[ L_p = 20 \log_{10} \left(\frac{p}{p_0}\right) ]

• (L

IS 3483: Classification of Noise Sources - Key Points

1. Noise Types (Clause 3.3)

• Continuous Noise: Source vibrates constantly (e.g., machinery hum).
• Impulsive Noise: Short duration, high intensity (e.g., drop forge hammer).

2. Frequency Distribution (Clause 4 & 7.5)

• Noise levels vary with frequency bands (commonly in c/s or Hz).
• Typical measurement distance d = 5 to 7.5 cm; larger for frequencies < 300 c/s.
• Loudness levels for various industrial operations are tabulated (Clause 7.5).

3. Absorption Coefficients (Appendix B, Clause 10.2)

4. Sound Pressure Level Reference

• Noise levels measured in dB relative to 0.0002 dyne/cm².

Summary Diagram: Noise Classification

IS 3483: Noise Measurement Techniques - Key Points

1. Noise Levels & Measurement

• Sound Pressure Level (SPL) is measured in decibels (dB), referenced to 0.0002 dyne/cm².
• Typical noise levels for industrial operations are frequency-dependent (e.g., 37.5 Hz to 4800 Hz bands).
• Measurement distance d = 5 to 7.5 cm; larger distances for frequencies < 300 c/s.

2. Noise Levels for Industrial Operations (Clause 7.5)

• Noise varies by operation (hammering, riveting, textile processes).
• Noise exposure limits and recommendations are frequency and time-dependent.

3. Absorption Coefficients (Appendix B, Clause 10.2)

4. Noise Reduction & Control (Clauses 9.2 & 9.4)

• Layout: Separate office from production; avoid common walls or use heavy walls with minimal openings.
• Enclosures/barriers: Use sound absorbers and barriers to reduce noise transmission.
• Hearing protection recommended based on exposure time and noise level (see Fig. 5 & 6 in code).

5.

IS 3483: Noise Levels in Industrial Operations - Key Points

1. Noise Levels (Clause 7.1 & Appendix A)

• Noise levels for various industrial operations are tabulated in Appendix A.
• Typical sound pressure levels (SPL) are referenced to 0.0002 dyne/cm².
• Examples include:
  • Drop forge hammer, hammering, riveting (Fig. 1)
  • Textile weaving, spinning (Fig. 2)
  • Carding, blowing in textile mills (Fig. 3)
  • Pneumatic tools (Fig. 4)
• SPL is frequency-dependent (bands in cycles/second, c/s).

2. Noise Reduction by Layout (Clause 9.2)

• Office spaces should be separate from production areas.
• If sharing a wall, it must be heavy with minimal openings to reduce noise transmission.

3. Hearing Conservation Criteria (Fig. 5 & 6)

• Recommended max SPL at ear for single exposure and daily exposure times.
• Ear protection is essential based on exposure duration and SPL:

• Rule of thumb: Halving exposure time allows 3 dB increase in permissible noise level.

4. Important Notes:

• Noise levels >10 dB above recommended curves require hearing preservation measures.
• Use broadband noise criteria for design and control.

Formula for Noise Dose Adjustment:

[ L_{allowable} = L_{base} + 3 \log_2 \left(\frac{T_{base}}{T_{actual}}\right) ]

Where:

• (L_{allowable}) = permissible noise level for actual exposure time
• (L_{base}) = base noise level for reference exposure time (T_{base})
• (T_{actual}) = actual exposure time

flowchart LR
    A[Industrial Operation] --> B[Noise Generation]
    B --> C[Measured SPL at Operator Position]
    C --> D{Exposure Time?}
    D -->|Full-time| E[Max SPL ~85

IS 3483 Key Points on Noise Control by Layout Planning

1. Noise Control by Location (Clause 9.1)

• Group noisy machines/processes together.
• Segregate noisy areas from quiet ones using buffer zones with intermediate noise levels.

2. Noise Reduction by Layout (Clause 9.2)

• Office spaces should be far from production areas, preferably in separate buildings.
• Avoid common walls; if unavoidable, walls must be heavy with minimal doors/openings.

3. Hearing Conservation (Fig. 5 & 6)

• Noise exposure limits depend on frequency and exposure time.
• Reducing exposure time by half allows a 3 dB increase in permissible noise level.
• Ear protection is essential above certain noise thresholds (see Fig. 5 & 6 for curves).

4. Absorption Coefficients (Appendix B, Clause 10.2)

5. Noise Level & Exposure Time Relation

• For every halving of exposure time, allowed noise level increases by 3 dB.

Summary Diagram: Noise Control by Layout

graph LR
  A[Noisy Machines] --> B[Group Together]
  B --> C[Buffer Zone]
  C --> D[Quiet Area]
  A --> E[Separate Office Building]
  E --> F[Heavy Walls, Minimal Openings]
 

IS 3483 - Noise Reduction Methods: Key Points

1. Noise Reduction at Source (Clause 9.3)

• Focus on minimizing noise generation directly at equipment or process.
• Use vibration isolation, proper maintenance, and quieter machinery.

2. Noise Reduction by Enclosures and Barriers (Clause 9.4)

• Enclosures should be heavy, airtight, and lined with sound-absorbing materials.
• Barriers reduce noise by blocking the direct path of sound waves.

3. Noise Reduction by Layout (Clause 9.2)

• Separate noisy production areas from office spaces.
• Avoid common walls; if unavoidable, use heavy walls with minimal openings.

4. Absorption Coefficients (Appendix B, Clause 10.2)

5. Noise Reduction Coefficient (NRC) Calculation (Typical)

[ \text{NRC} = \frac{\alpha_{250} + \alpha_{500} + \alpha_{1000} + \alpha_{2000}}{4} ]

where (\alpha_f) = absorption coefficient at frequency (f).

6. Recommended Noise Exposure Limits (Fig. 5 & 6)

• Ear protection essential above 85 dB for full-time exposure.
• Exposure time halves for every 3

IS 3483: Acoustical Absorption Devices - Key Data

1. Absorption Coefficients of Typical Functional Sound Absorbers (Appendix B, Clause 10.2)

Note: Fibre glass packing density = 70 kg/m³.

2. Loudness Levels for Various Industrial Operations (Clause 10.2)

Vibration Isolation per IS 3483

Key Concepts:

• Isolator Materials: Steel springs, rubber, cork, felt.
• Isolator Position: Normally between machine & foundation; for low forcing freq. (<10 c/s), mount machine on heavy concrete base with isolators below.
• Critical Installation: Mount isolators at the machine's center of gravity plane and laterally far from center.
• Avoid rigid ties: Use flexible connections or pipe bends to prevent vibration short-circuiting.

Important Formulas & Relations:

1. Natural Frequency (f_n) from Static Deflection (δ):

[ f_n = \frac{1}{2\pi} \sqrt{\frac{g}{\delta}} ]

• (g) = acceleration due to gravity (9.81 m/s²)
• (\delta) = static deflection under load (m)

2. Transmissibility (T):

[ T = \frac{\text{Transmitted displacement}}{\text{Exciting displacement}} ]

• Depends on ratio (r = \frac{f}{f_n}) (forcing freq / natural freq)
• For (r \geq 3), good isolation achieved (transmissibility < 1)

Tables & Figures Summary:

Design Recommendations:

• Frequency ratio (r = f / f_n \geq 3)
• Locate isolators at CG plane.
• Use heavy inertia blocks for impact machines.
• Insert flexible connections in pipes.

graph LR
A[Machine] -->|Vibration| B[Isolator (spring/rubber/cork)]
B -->|Reduced vibration| C[Foundation]
B -.-> D[Flexible pipes/conduits]
D --> C

Summary: Use resilient mounts

IS 3483: Hearing Protection and Exposure Limits

Key Points from IS 3483

• Noise Reduction by Layout (Clause 9.2):

  • Office spaces should be segregated from production areas, preferably in separate buildings.
  • If a common wall exists, it must be heavy, with minimal doors and no permanent openings.

• Damage-Risk Criteria (Clause 8.1):

  • Safe exposure limits for continuous noise (8 hours/day, 6 days/week) are defined by octave-band noise level curves (Fig. 5).
  • Hearing protection is recommended if noise exceeds these levels to prevent permanent damage.

Exposure Limits & Hearing Protection Recommendations

• Note: Halving exposure time allows a 3 dB increase in permissible noise level (Fig. 6).

Important Formula for Noise Dose Adjustment

[ L_{eq,new} = L_{eq,old} + 10 \log_{10} \left(\frac{T_{old}}{T_{new}}\right) ]

Where:

• (L_{eq}) = Equivalent continuous noise level
• (T) = Exposure time

Summary Diagram (Exposure vs Protection)

graph LR
A[Noise Level (dB)] --> B[Exposure Time]
B --> C{Protection Needed?}
C -->|Full-time >85 dB| D[Recommended]
C -->|10% time >90 dB| E[Essential]
C -->|1% time >95 dB| F[Essential]
C -->|Single exposure >100 dB| G[Essential]

References:

• Fig. 5 & 6 of IS 3483 for octave-band noise curves and exposure time vs noise level charts.
• Protection devices: ear-plugs, ear-defenders recommended when noise levels exceed limits.

IS 3483: Maintenance & Operational Practices for Noise Reduction

Key Points from IS 3483:

1. Noise Reduction by Maintenance (Clause 9.3.2)

• Minimize impact noise: Use soft/resilient materials on containers.
• Rubber tyres: Fit on trucks, trolleys to reduce noise.
• Proper lubrication: Reduces friction noise in conveyors, rollers, machines.
• Regular maintenance: Keeps machine noise at minimum.

2. Noise Reduction by Enclosures and Barriers (Clause 9.4)

• Use enclosures/barriers around noisy equipment to block sound propagation.

3. Absorption Coefficients of Sound Absorbers (Appendix B, Clause 10.2)

Practical Noise Control Formula

Noise Reduction (dB) by Barrier:

[ NR = 20 \log_{10} \left(\frac{d_1 + d_

Noise Control via Enclosures and Barriers (IS 3483: Clause 9.4)

1. Enclosures (Clause 9.4.1)

• Purpose: Reduce airborne noise by enclosing the machine.
• Types:
  • Close-fitting acoustic box (operator outside).
  • Room-sized enclosure lined with sound-absorbing material.
• Material: Sheet metal lined with acoustic absorbers.
• Walls: Must have adequate transmission loss (refer IS 1950-1962).

2. Barriers (Clause 9.4.2)

• Partial noise reduction using:
  • Two-sided or three-sided barriers.
  • Barriers covered on machine side with sound-absorbing material.
  • Openings facing walls with absorptive material.
  • Overhead sound-absorbing material if top is open.

Key Absorption Coefficients (Appendix B, Clause 10.2)

Noise Reduction by Barriers Formula (Conceptual)

[ \text{Noise Reduction (dB)} \approx 10 \log_{10} \left(\frac{d_1 + d_2}{d_1 + d_2 + 2h}\right) ]

• (d_1,

IS 3483: Key References, Tables & Specifications Summary

1. Absorption Coefficients (Appendix B, Clause 10.2)

• Packing density of fibre glass: 70 kg/m³.
• Note: Thickness (d) usually 5 to 7.5 cm; larger values for frequencies < 300 Hz.

2. Noise Levels (Clause 2.5)

• Noise levels measured at operator positions for various industrial operations (hammer