Recommendations for local exhaust ventilation systems in premises manufacturing products containing asbestos

IS 12080: Scope - Key Specifications & Tables

1. Scope Summary

• Covers inspection, testing, and maintenance of exhaust ventilation systems.
• Emphasizes both weekly and yearly checks to ensure system efficiency and safety.

2. Yearly Inspection Checklist (Appendix E, Clause 8.1.3)

• Verify all hoods and ducts are intact.
• Check for air leakages.
• Inspect filter elements and cleaning mechanisms.
• Ensure lubrication points are charged.
• Confirm fan and drive conditions.
• Measure airflow and fan inlet pressure against design specs.

Note: Some items (wear, lubrication, fan condition) should be checked quarterly.

3. Typical Exhaust Rates (Table 1, Clause 2.1)

4. Ducting Sheet Thickness (Clause 2.1, Table B-2)

5. SI Units Used

• Length: metre (m)
• Pressure: pascal (Pa) = N/m²
• Flow: m³/min

flowchart TD
    A[Machine] --> B[Exhaust Rate]
    B --> C{Connection Type}
    C -->|Top| D[Rate m³/min]
    C -->|

IS 12080: Local Exhaust Ventilation (LEV) for Asbestos Product Manufacturing

General Principles of LEV (Clause 3.1 & 4)

• Applicability: All operations generating asbestos dust (e.g., cutting, mixing, spinning).
• Objective: Capture dust at the source to prevent airborne asbestos fiber exposure.

Key Specifications & Formulas

1. Capture Velocity (V_c):
   Minimum air velocity required at the hood opening to capture contaminants.
   Typical range for asbestos dust:
   [ V_c = 0.5 \text{ to } 2.5 , m/s ]

2. Volumetric Flow Rate (Q):
   [ Q = A \times V_c ]
   Where:

   • ( A ) = Area of hood opening (m²)
   • ( V_c ) = Capture velocity (m/s)

3. Duct Velocity (V_d):
   To prevent dust settling inside ducts:
   [ V_d \geq 15 , m/s ]

4. Hood Design:

   • Should be as close as possible to the emission source.
   • Enclose the source partially or fully.

Typical Capture Velocity Recommendations for Asbestos Dust

Summary Diagram

flowchart LR
    Source[Asbestos Dust Source]
    Hood[Local Exhaust Hood]
    CaptureVelocity[Capture Velocity Vc]
    Duct[Duct with Velocity Vd >= 15 m/s]
    Fan[Exhaust Fan]
    Filter[Filter/Collector]

    Source --> Hood --> Duct --> Fan --> Filter
    Hood -.-> CaptureVelocity
    Duct -.-> DuctVelocity

Note: Always ensure regular maintenance and monitoring of LEV systems for effective asbestos dust control as per IS 12080.

IS 12080: Hood Design and Placement - Key Points

1. Hood Air Velocity (Clause 4.2.2)

• Captor-type hood: Air velocity must be sufficient to entrain dust.
• Enclosure-type hood: Must maintain negative pressure inside to prevent dust escape.
• Opening size: Should be minimized to reduce air volume and maintain efficiency.

2. Hood Shape & Position (Clauses 5.2.2 & 5.2.3)

• Hood should be close to the dust source and ideally enclose it.
• Shape must streamline dust particles toward the hood mouth for effective capture.

3. Design Considerations (Clause 4.2)

• Locate dust source and free dust path using high intensity light beams.
• Design hood to cover the source and direct dust flow efficiently.

Typical Formula for Airflow (from Appendix A guidance):

[ Q = A \times V ]

• (Q) = Air volume flow rate (m³/s)
• (A) = Hood opening area (m²)
• (V) = Capture velocity (m/s), typically 0.5 to 2.5 m/s depending on dust type

Summary Table: Capture Velocity Guidelines

flowchart LR
    DustSource((Dust Source))
    HoodMouth((Hood Mouth))
    Airflow[Airflow Direction]
    DustParticles((Dust Particles))

    DustSource -->|Dust Emission| DustParticles
    DustParticles -->|Streamlined| HoodMouth
    HoodMouth -->|Suction| Airflow

In brief: Minimize hood opening, maintain adequate capture velocity, position hood close to source, and design shape to guide dust efficiently into the hood.

IS 12080 - Ducting Requirements (Clause 4.3.1 & Appendix B)

Key Specifications:

• Duct Shape: Circular section, mild steel.
• Interior Surface: Smooth, obstruction-free.
• Air Velocity:
  • Minimum: 17.5 m/s
  • For dust with metal particles: up to 22.5 m/s

Thickness of Mild Steel Sheet (Table B-2):

General Principles:

• Size ducts to maintain adequate air velocity.
• Use generous radii for bends.
• Connect to main ducts from top or side only.
• Provide access doors near bends and at intervals.
• Install test points for monitoring.
• Ensure stable support for all ducting.

flowchart LR
    A[Circular Duct] --> B[Minimum Velocity 17.5 m/s]
    B --> C{Dust Particles?}
    C -- Yes --> D[Velocity up to 22.5 m/s]
    C -- No --> E[Maintain 17.5 m/s]
    A --> F[Smooth Interior]
    A --> G[Generous Bend Radii]
    A --> H[Connections from Top/Side]
    A --> I[Access Doors & Test Points]
    A --> J[Stable Supports]

This ensures efficient air conveyance and durability per IS 12080.

IS 12080: Dust Collection and Filtration Key Points

1. Exhaust Air Volumes (Clause 2.1, Table 1)

2. Dust Collectors (Clause 4.4)

• Two main types:
  • Cyclones
  • Fabric filter collectors

3. Filter Area Calculation (Clause 4.4.2.2)

[ \text{Total filter area} = \frac{\text{Volume of air to be handled (m}^3/\text{min)}}{\text{Filtering speed (m/min)}} ]

• Filtering speed depends on filter media and dust type.
• Ensure adequate filter area to maintain efficiency and minimize pressure drop.

4. Fine Dust Collection (Clause 9.1)

• Use fixed extraction systems with:
  • Filtered air discharge
  • Dust collected in hoppers with bagging-off outlets
  • Polyethylene bags for visibility and easy changing
  • Design to minimize dust leakage during bag change

flowchart LR
    A[Machine Dust Source] --> B[Hood Capture]
    B --> C[Exhaust System]
    C --> D{Dust Collector}
    D -->|Cyclone| E[Cyclone Unit]
    D -->|Fabric Filter| F[Filter Unit]
    F --> G[Filtered Air]
    E --> G
    F --> H[Collected Dust in Hopper]
    H --> I[Bagging-off Outlet]

Summary: Design dust collection based on machine exhaust rates (Table 1), use

IS 12080: Low-Volume, High-Velocity Exhaust Systems (Clause 6.1)

Key Specifications:

• Capture Velocity: 50 to 60 m/s (very high velocity)
• Air Volume: 0.3 to 7 m³/min (low volume)
• Application: Hand tools, machining operations, dust control at source
• Hoods/Nozzles: Close-fitting, custom-made, placed very near dust source
• Ducting: Small-bore plastic hose near tool; fixed steel piping elsewhere
• Operator Safety: Operator must not stand between hood and dust source (Clause 5.2.7)

Design Principles:

• High velocity compensates for low volume by proximity to source.
• Flexible hose ensures tool mobility.
• System is less bulky than high-volume, low-velocity systems.

Formula for Volumetric Flow Rate (Q):

[ Q = A \times V ] Where:

• (Q) = Air volume (m³/s)
• (A) = Cross-sectional area of nozzle (m²)
• (V) = Capture velocity (m/s)

Typical Values:

Example Calculation:

For a 30 mm diameter nozzle at 50 m/s: [ A = \pi \times (0.015)^2 = 7.07 \times 10^{-4} , m^2 ] [ Q = 7.07 \times 10^{-4} \times 50 = 0.035 , m^3/s = 2.1 , m^3/min ]

flowchart LR
    Dust_Source -->|Dust particles| Hood[Close-fitting Hood]
    Hood -->|Exhaust air at 50-60 m/s| Hose[Small-bore Hose]
    Hose --> Steel_Pipe[Fixed Steel Piping]
    Steel_Pipe --> Exhaust_Fan[Exhaust Fan]

This system ensures **

IS 12080: System Balancing and Airflow Control Key Points

1. System Balancing (Clause 7.1)

• Balancing devices:
  • Balancing cones: Fixed, tamper-proof, require access doors for adjustment.
  • Slide dampers: Adjustable externally, must be locked after initial setting to prevent tampering.

2. Airflow Measurement (Clause 9.1)

• Test holes:
  • Diameter: 10 mm
  • Purpose: Check airflow at various points.
  • Must be covered when not in use.

3. Duct Design & Airflow (Clause 4.3.1 & Appendix B)

• Duct sizing: Circular ducts sized for adequate air velocity.
• Surface: Smooth interior to reduce friction losses.
• Bends: Generous radii to minimize pressure drop.
• Connections: From top or side; avoid upward connections from bottom of main duct.
• Access: Doors near bends and intervals for maintenance.
• Support: Proper supports for stability.

4. Typical Airflow Velocities (Clause 2.2 & Table 2)

Summary Formula for Airflow (Q), Velocity (V), and Duct Area (A):

[ Q = A \times V ]

• Q: Volumetric airflow (m³/s)
• A: Cross-sectional area of duct (m²)
• V: Air velocity (m/s)

flowchart LR
    A[Air Source] --> B[Ducting System]
    B --> C{Balancing Device}
    C -->|Balancing Cone| D[Fixed, Access Door]
    C -->|Slide Damper| E[Adjustable, Locked]
    B --> F[Test Holes (10 mm)]
    B --> G[Access Doors Near Bends]
    B --> H[Supports for Stability]

Note: Always lock slide dampers post-adjustment to maintain system balance integrity.

IS 12080: Inspection, Testing & Maintenance of Exhaust Ventilation Systems

Key Specifications (Clause 8.1.3 & Appendix E)

Yearly Examination & Testing Checklist:

• Hoods & ducting: Confirm all are present and in good condition.
• Air leakages: Ensure no leaks in any part of the system.
• Filter elements: Check for good condition.
• Wear & tear: Inspect filter shaking/cleaning gear for unacceptable wear.
• Lubrication: All lubrication points must be charged.
• Fan & drive: Verify condition and correct adjustment.
• Air flow & pressure: Confirm airflow and fan inlet pressure meet design specs.

Note: Items on wear, lubrication, and fan condition should also be checked quarterly.

Weekly Inspection (Appendix D)

• General handling and operational checks to ensure system integrity.

Testing & Measurement Tips

• Use permanent gauges mounted on rigid parts near test points (Clause 7.4.1).
• Connect gauges with small-bore piping for accurate pressure readings.

SI Units Reference (for Measurements)

flowchart TD
    A[Yearly Inspection] --> B[Check Hoods & Ducting]
    A --> C[Check Air Leakages]
    A --> D[Inspect Filters]
    A --> E[Check Wear & Lubrication]
    A --> F[Verify Fan & Drive]
    A --> G[Measure Air Flow & Pressure]
    E --> H[Quarterly Check on Wear & Lubrication]

Summary: Follow Appendix E checklist annually, with quarterly focus on mechanical wear and lubrication, ensuring system performance and safety.

IS 12080: Dust Handling and Disposal – Key Points

1. Air Requirements (Clause 4.2.2 & Appendix A)

• Air quantity depends on hood design and proximity to dust source.
• Total air volume from all hoods determines collector and fan sizes.
• Air velocity at dust origin must be sufficient to capture dust.
• Hoods must be designed for effective dust capture.

2. Typical Exhaust Rates (Clause 2.1, Table 1)

3. Fine Dust Collection (Clause 9.1)

• Use fixed extraction systems with air filtration.
• Dust collects in hoppers fitted with bagging outlets.
• Polyethylene bags of adequate strength, visible dust levels.
• Design outlets for easy bag changing and minimal dust leakage.

4. Waste Other Than Fine Dust (Clause 9.2)

• Follow specific disposal guidelines (not detailed here).

flowchart LR
    Dust_Source --> Hood[Hood Design]
    Hood -->|Capture dust| Air_Extraction[Air Extraction System]
    Air_Extraction --> Collector[Collector & Hopper]
    Collector --> Bagging[Bagging Outlet with Polyethylene Bag]
    Bagging --> Disposal[Disposal of Dust]

This summarizes IS 12080 dust handling essentials for design and disposal.

IS 12080: Guidelines for Assessment of Air Requirements (Clause 4.2.2 & Appendix A)

Key Points:

• Air quantity depends on hood design and distance from dust source.
• Sum of air volumes for all hoods determines collector and fan sizes.
• Air velocity at dust origin must be sufficient to capture dust.
• Hood openings should be minimum necessary to avoid excess air volume.

Typical Exhaust Rates (Table 1)

Airflow/Capture & Transport Velocities (Table 2)

IS 12080: Recommendations for Ducting (Clause 4.3.1, Appendix B)

Key Specifications:

• Duct Shape & Material:

  • Circular section, mild steel.
  • Interior surface smooth, free of obstructions.

• Air Velocity:

  • Minimum air conveying velocity: 17.5 m/s.
  • For dust with metal particles: up to 22.5 m/s.

• Duct Thickness (Mild Steel Sheet):

• Ducting Layout:
  • Bends with generous radii.
  • Connections from top or side only (no upward bottom connections).
  • Access doors near bends and at intervals.
  • Test points for inspection.
  • Adequate support for stability.

Summary Diagram:

flowchart TD
    A[Circular Mild Steel Duct] --> B[Minimum Velocity: 17.5 m/s]
    B --> C[Up to 22.5 m/s for dust]
    A --> D[Thickness by Diameter]
    D --> D1[≤300 mm: 0.90 mm]
    D --> D2[300-750 mm: 1.25 mm]
    D --> D3[750-1000 mm: 1.60 mm]
    D --> D4[>1000 mm: 2.00 mm]
    A --> E[Smooth Interior & Generous Bends]
    A --> F[Connections: Top or Side Only]
    A --> G[Access Doors & Test Points]
    A --> H[Proper Support for Stability]

This ensures efficient airflow, durability, and maintainability of ducting systems per IS 12080.

IS 12080 - Guidelines for Operation of Local Exhaust Ventilation (LEV) System

Key Operational Guidelines (Clause 4.6, Appendix C):

• System Start-Up:
  Ensure exhaust system is ON and suction is felt at all extraction hoods before starting machines.

• During Short Stoppages:
  Keep LEV running to prevent asbestos dust escape during maintenance or repairs.

• Shutdown Procedure:
  Run exhaust system for at least 2 minutes after machine stops to clear ducts and hoods.

• Filter Cleaning:
  Manually operate shaking gear filters during breaks or use automatic shaking if available.

• Damper Settings:
  Dampers used for initial balancing must be locked and not readjusted except by trained personnel.

• Weekly Inspection:
  Check for obstructions in hoods and verify hood positions using the light beam method to ensure effectiveness.

Additional Notes:

• Maintain continuous exhaust airflow to contain asbestos dust.
• Regular maintenance and inspection ensure system efficiency and worker safety.

flowchart TD
    A[Start Machine] --> B{Exhaust ON & Suction Felt?}
    B -- Yes --> C[Operate Machine]
    B -- No --> D[Switch ON Exhaust]
    C --> E[Short Stoppage?]
    E -- Yes --> F[Keep Exhaust ON]
    E -- No --> G[End Shift]
    G --> H[Run Exhaust for 2 mins]
    F --> I[Maintenance Work]
    I --> J[Exhaust ON to prevent dust escape]
    H --> K[Stop Exhaust]

This concise operational framework ensures effective asbestos dust control per IS 12080.