Recommendations for control of emission of asbestos dust in premises manufacturing products containing asbestos, Part 1: Asbestos cement products

IS 11770 Part 1 - Scope and Key Specifications

Scope:

• Applies to asbestos cement products manufacturing.
• Emphasizes safety and control of asbestos dust emissions.
• Aligns with international standards, including ILO Codes of Practice (1984).

Key Specifications:

• Waste Disposal:
  All asbestos waste must be disposed as per IS 11768:1986.

• Dust Control (Amendment 2005):
  Processes generating dust above permissible limits must be isolated and enclosed.

• Empty Bags:
  Should be shredded and either recycled or disposed according to IS 11768:1986.

Units & Symbols (SI Units used in IS 11770 Part 1)

Summary Diagram: Dust Control Process

flowchart LR
    A[Process generating dust] --> B{Dust level > Permissible Limit?}
    B -- Yes --> C[Isolate process]
    C --> D[Provide enclosure]
    D --> E[Control dust emission]
    B -- No --> F[Normal operation]

For detailed formulas and tables, refer to IS 11770 Part 1 full text and IS 11768:1986 for waste disposal.

IS 11770 Part 1 (1987) - Definitions & Key Specifications Summary

Scope:

• Covers recommendations for control of asbestos dust emission in asbestos cement product manufacturing.
• Aligns with international standards, notably ILO Codes of Practice on asbestos safety (1984).

Key Definitions & Units (SI System)

Important Specifications

• Waste Disposal: Asbestos waste must be handled per IS 11768:1986.
• Dust Control: Processes generating dust above permissible limits must be isolated and enclosed.
• Bag Handling: Empty asbestos bags should be shredded and recycled or disposed of as per IS 11768:1986.

Summary Diagram: Dust Control Process

flowchart TD
    A[Asbestos Cement Manufacturing] --> B{Dust Generation}
    B -->|Below Limit| C[Normal Ventilation]
    B -->|Above Limit| D[Isolation & Enclosure]
    D --> E[Dust Extraction & Filtration]
    E --> F[Safe Emission Levels]

Note: For detailed exposure limits, dust control methods, and disposal procedures, refer to IS 11768:1986 and the amendment

IS 11770 Part 1: Control of Asbestos Dust - Key Recommendations

This part focuses on asbestos cement product manufacturing and aims to minimize worker exposure to harmful asbestos dust.

Key Points:

• Airborne asbestos dust concentration must be monitored as per IS 11450:1986.
• Emission control involves:
  • Proper ventilation systems (local exhaust ventilation preferred).
  • Use of dust suppression techniques (wetting, enclosure).
  • Personal protective equipment (PPE) for workers.
• Health surveillance and periodic medical checkups are essential.
• Safe packaging, transport, and disposal of asbestos waste to prevent dust release.

Typical Control Measures Summary:

Formula for Dust Concentration (General Concept):

[ C = \frac{M}{V} ]

• C = concentration of asbestos dust (fibers/cm³)
• M = mass of asbestos fibers collected
• V = volume of air sampled

flowchart LR
    A[Raw Asbestos Handling] --> B[Wet Processing]
    B --> C[Local Exhaust Ventilation]
    C --> D[Airborne Dust Monitoring (IS 11450)]
    D --> E[Worker PPE & Health Surveillance]
    E --> F[Safe Packaging & Transport]
    F --> G[Disposal of Waste]

This ensures comprehensive control of asbestos dust emissions in manufacturing premises.

IS 11770 Part 1 (1987) - Recommended Control Measures for Asbestos Dust

Key Control Measures

1. Engineering Controls (Clause 3.2)

• Dust Suppression:

  • Use wet methods to suppress dust at source.

• Dust Dilution:

  • Modify dust-generating systems.
  • Separate processes and automate.
  • Provide general ventilation with clean air.

• Dust Extraction:

  • Use enclosures or booths.
  • Design efficient hoods.
  • Employ vacuum cleaners to prevent dust spread.

• Dust Conveyance:

  • Use balanced ductwork with appropriate air velocities (typically 15-20 m/s for dust transport).

• Dust Collection:

  • Install effective filters (e.g., HEPA filters).

• Separate Workplaces:

  • Isolate high dust-generating operations beyond permissible exposure limits.

2. Work Practices (Clause 3.3)

• Maintain machinery and ventilation systems properly.
• Clean machinery and areas regularly using methods per IS 11767-1986.
• Use personal protective equipment (PPE) as per IS 12078-1987.

Typical Air Velocity for Dust Conveyance

Summary Diagram: Dust Control Measures

flowchart TD
    A[Dust Generation] --> B[Engineering Controls]
    B --> B1[Wet Methods]
    B --> B2[Dust Dilution]
    B --> B3[Dust Extraction]
    B --> B4[Dust Conveyance]
    B --> B5[Dust Collection]
    B --> B6[Separate Workplaces]
    A --> C[Work Practices]
    C --> C1[Maintain Equipment]
    C --> C2[Regular Cleaning]
    C --> C3[PPE Usage]

References:

• IS 11767:1986 (Cleaning methods)
• IS 12078:1987 (PPE for asbestos)

IS 11770 Part 1: General Ventilation Key Points

• Clause 5.2: Ventilation flow rates must ensure sufficient air changes to maintain workplace safety and health.

• Air Change Rate (ACH): Typically, for general ventilation, 6 to 12 air changes per hour is recommended depending on the process and pollutant level.

• Ventilation Flow Rate (Q) formula:

  [ Q = V \times N ]

  Where:

  • (Q) = ventilation flow rate (m³/hr)
  • (V) = volume of the workplace (m³)
  • (N) = number of air changes per hour (ACH)

• Dust Control (Clause 4.7.1 & 3.2.1.5):

  • Use exhaust hoods or booths to capture dust.
  • Airflow should be downwards to prevent dust inhalation.
  • Design ventilation to avoid turbulence and eddies that reduce dust removal efficiency.

Typical Ventilation Specifications Summary

flowchart LR
    A[Workplace Volume V] --> B[Calculate Flow Rate Q = V × ACH]
    B --> C{Ventilation System}
    C --> D[General Ventilation: 6-12 ACH]
    C --> E[Local Exhaust Hood]
    E --> F[Downward Airflow to Capture Dust]
    F --> G[Minimize Turbulence & Eddies]

Summary: Ensure ventilation flow rates provide adequate air changes, use downward airflow to control dust, and design exhaust systems to avoid turbulence for effective dust removal.

Maintenance and Cleaning of Premises (IS 11770 Part 1)

Key Specifications:

• Clause 5.3: Exhausted air must be efficiently filtered; recirculation of asbestos dust-laden air back to the workspace is prohibited.

• Clause 6.1:

  • Premises must be kept clean and free from asbestos waste.
  • All machinery, plant, equipment, and surfaces (including exhaust ventilation and building interiors) must be dust-free.
  • Cleaning must comply with IS 11767-1986 (Recommendations for cleaning using asbestos fibers).

• Clause 7.1 (Disposal):

  • Waste disposal must follow IS 11768-1986 (Recommendations for asbestos waste disposal).

Summary Table for Cleaning & Disposal Standards

Important Notes:

• Cleaning methods: Use wet cleaning or vacuum systems with HEPA filters to minimize airborne asbestos fibers.
• Air filtration: Use high-efficiency particulate air (HEPA) filters.
• Waste handling: Asbestos waste should be sealed, labeled, and disposed of per IS 11768 guidelines.

flowchart TD
    A[Asbestos Processing Plant] --> B[Exhaust Ventilation]
    B --> C[HEPA Filters]
    C --> D[Filtered Air Discharged]
    A --> E[Cleaning: Wet & Vacuum Methods]
    E --> F[Asbestos Waste]
    F --> G[Sealed Disposal per IS 11768]

References:

• IS 11767-1986: Cleaning recommendations using asbestos fibers
• IS 11768-1986: Disposal of asbestos waste
• IS 11770 Part 1: Air filtration & premises maintenance

Disposal of Waste as per IS 11770 Part 1 (1987)

Key References:

• Waste disposal must comply with IS 11768-1986 (Recommendations for disposal of asbestos waste).
• Clause 7.1: All waste material disposal follows IS 11768-1986 provisions.

Important Specifications:

1. Recycling of Waste (Clause 4.6)

• Dry Waste Recycling (4.6.1):

  • Pulverize dry asbestos cement waste in an enclosed system with exhaust.
  • Alternatively, use wet grinding (ball mill) to prevent dust escape.

• Green Waste Recycling (4.6.2):

  • Side cuttings during manufacturing must be fully recycled back into the process.

2. Empty Bags Disposal (Amendment 2005)

• Empty bags should be shredded and recycled or disposed according to IS 11768:1986.

Summary Table: Waste Disposal Process

Notes:

• Emphasis on dust control by isolation and enclosures (Amendment 2005).
• Follow IS 11768-1986 for detailed asbestos waste disposal methods.
• Use closed systems to prevent airborne asbestos fibers.

flowchart TD
    A[Asbestos Cement Waste] --> B{Type of Waste}
    B -->|Dry Waste| C[Pulverize in enclosed system]
    B -->|Dry Waste| D[Wet grinding (ball mill)]
    B -->|Green Waste| E[Recycle into process]
    B -->|Empty Bags| F[Shred and recycle or dispose per IS 11768]
    C --> G[Dust control via exhaust]
    D --> G

For detailed procedures, refer IS 11768-1986 alongside IS 11770 Part 1.

IS 11770 Part 1 references IS 12078-1987 for Personal Protective Equipment (PPE) related to asbestos handling.

Key Points on PPE (from IS 12078-1987 & related clauses):

• PPE Use is mandatory where asbestos dust exposure cannot be eliminated by enclosure or ventilation.
• PPE includes:
  • Respiratory protective devices (e.g., masks or respirators suitable for asbestos fibers)
  • Protective clothing that prevents asbestos dust contamination
• PPE must be properly maintained and regularly inspected.
• Work practices must ensure:
  • Proper use of PPE
  • Regular cleaning of PPE and work areas (see IS 11767-1986)
• Local exhaust ventilation (per IS 12080-1987) should be used wherever total enclosure is not possible.

Summary Table (PPE for Asbestos Handling)

Important Formula/Specification:

• No direct formula in IS 11770 Part 1 for PPE; focus is on selection, maintenance, and usage.
• Follow ventilation standards (IS 12080-1987) for dust control alongside PPE.

flowchart LR
    A[Dust-Producing Process] -->|If enclosure not possible| B[Local Exhaust Ventilation (IS 12080)]
    B --> C{Is dust exposure controlled?}
    C -->|Yes| D[Minimal PPE required]
    C -->|No| E[Use PPE (Respirators, Clothing, Gloves)]
    E --> F[Regular Maintenance & Cleaning (IS 11767, IS 12078)]

In summary: Use PPE as per IS 12078-1987 when engineering controls are insufficient, maintain PPE rigorously, and combine with proper work practices and ventilation.

Measurement of Airborne Asbestos Concentration as per IS 11770 Part 1

• The airborne asbestos fiber concentration in the workplace is measured following IS 11450:1986.
• This standard specifies the membrane filter method using light microscopy for fiber counting.
• Key steps include:
  • Air sampling through a membrane filter.
  • Counting fibers under a microscope.
  • Calculating fiber concentration as fibers per cubic centimeter (f/cc).

Key Formula for Fiber Concentration:

[ C = \frac{N}{V} ]

Where:

• ( C ) = asbestos fiber concentration (fibers/cm³)
• ( N ) = total number of fibers counted
• ( V ) = volume of air sampled (cm³)

Important Specifications:

• Minimum fiber length counted: 5 µm
• Aspect ratio (length to diameter): ≥ 3:1
• Sampling flow rate and duration as per workplace conditions to ensure representative results.

Summary Table (Typical Parameters):

For detailed procedure, refer to IS 11450:1986.

flowchart LR
    A[Air Sampling Pump] --> B[Membrane Filter]
    B --> C[Microscopic Analysis]
    C --> D[Count Fibers >5µm & Aspect Ratio ≥3:1]
    D --> E[Calculate Concentration (fibers/cm³)]

IS 11770 Part 1: Packaging, Transport, and Storage - Key Points

Packaging & Handling (Clause 4.1.2 & 4.3)

• Palletized Handling: Arrange palletized loads to avoid damage to bags and facilitate mechanized handling.
• Handling Finished Products: Handle with care to prevent damage and dust emission.

Transport

• Use secure packaging to prevent spillage and damage during transit.
• Follow mechanized handling practices as per Clause 4.1.2.

Storage

• Store in dry, well-ventilated covered areas to avoid moisture damage.
• Stack bags/pallets to prevent crushing and deformation.

Waste Disposal (Clause 7.1)

• Dispose of asbestos waste per IS 11768:1986.
• Empty bags must be shredded and recycled or disposed as per IS 11768.

Important Table: Disposal of Waste (Clause 7.1)

Units & Definitions (SI Units)

• Force: Newton (N) = 1 kg·m/s²
• Pressure/Stress: Pascal (Pa) = 1 N/m²
• Energy: Joule (J) = 1 N·m

Summary Diagram: Handling Flow

flowchart LR
    A[Finished Products] --> B[Palletized Packaging]
    B --> C[Mechanized Handling]
    C --> D[Transport]
    D --> E[Storage (Dry, Covered)]
    E --> F[Use or Disposal]
    F -->|Waste| G[Dispose per IS 11768]

Note: Always ensure compliance with dust control and safety provisions as per IS 11770 amendments (e.g., enclosures for dust-generating processes).

IS 11770 Part 1 focuses on safety and health in asbestos handling, referencing international standards like ILO Codes of Practice and IS 11451-1986 for occupational exposure.

Health Supervision and Monitoring (Key Points)

• Health supervision involves periodic medical examinations of workers exposed to asbestos.
• Monitoring includes regular air sampling and analysis to ensure exposure limits are not exceeded.
• Exposure limits typically align with threshold limit values (TLVs) or permissible exposure limits (PELs) defined in IS 11451 or ILO guidelines.
• Medical tests include chest X-rays, lung function tests, and symptom questionnaires to detect early signs of asbestosis or related diseases.

Typical Exposure Limits (from IS 11451 / ILO)

Monitoring Frequency

• Air monitoring: Monthly or quarterly depending on risk.
• Health checks: Annually or biannually.

flowchart LR
  A[Worker Exposure] --> B[Air Sampling]
  B --> C{Exposure < Limit?}
  C -- Yes --> D[Continue Monitoring]
  C -- No --> E[Implement Controls]
  A --> F[Medical Examination]
  F --> G{Health Status}
  G -- Normal --> D
  G -- Abnormal --> H[Medical Intervention]

For detailed formulas or tables, refer to IS 11451-1986 and ILO Codes of Practice. IS 11770 Part 1 aligns with these for health supervision protocols.

IS 11770 Part 1: Recycling of Asbestos Cement Waste - Key Points

1. Dry Waste Recycling (Clause 4.6.1)

• Process: Pulverize asbestos cement dry waste in an enclosed system with exhaust to prevent dust escape.
• Alternative: Use ball mill grinding in wet condition to suppress dust.
• Goal: Minimize airborne asbestos fibers for environmental safety.

2. Green Waste Recycling (Clause 4.6.2)

• Side cuttings from sheet manufacturing are fully recycled back into the production process.

3. Reuse of Collected Dust (Clause 4.6.3)

• Asbestos fibrous dust from bag filters and cement dust from pulverizers must be recycled without compromising product quality.

4. Waste Disposal (Clause 7.1)

• Recycle asbestos cement waste to the maximum extent possible.
• Residual waste disposal must comply with IS 11768:1986.

Summary Table

Important Note:

• For low-density products (<1.20 density), refer to recommendations in Clauses 4.4.3 and 4.4.4 for specific recycling guidelines.

flowchart TD
    A[Asbestos Cement Waste] --> B{Type of Waste}
    B -->|Dry Waste| C[Pulverize in enclosed system]
    B -->|Green Waste| D[Recycle fully in process]
    B -->|Collected Dust| E[Recycle into process]
    C --> F[Use exhaust system to avoid dust]
    C --> G[Or wet ball mill grinding]
    F & G --> H[Safe recycling]
    D & E --> H