How to Control Dust & Fumes in Metal Processing

1. Install Local Exhaust Ventilation (LEV) Systems

LEV systems capture dust and fumes at their source — before they reach the breathing zone. Properly designed hoods and ducts are essential for processes like plasma cutting, grinding, and welding.
Use the guidelines of IS 14166 for ventilation rates, hood design, and capture velocity.

2. Design Hoods and Ducts Properly

The effectiveness of an LEV depends on capture velocity, hood geometry, and placement. Even a few centimetres’ deviation can reduce performance. Consult professional ventilation engineers to design ducts that maintain recommended air velocities and static pressures.

3. Select the Right Dust Collector

Use equipment matched to your application:

• Cartridge Dust Collectors – ideal for fine metal dust and welding fumes.

• Baghouse Collectors – suitable for heavy-dust processes such as grinding or shot-blasting.

• Wet Scrubbers – recommended for combustible-metal dusts and spark-prone environments.

Ensure collectors meet emission norms under CPCB Guidelines for Emission Standards for Foundries and Metal Industries.

4. Use High-Efficiency Filtration

Install HEPA or ULPA filters downstream of primary collectors for ultra-fine fumes or toxic metals. Maintain filters according to manufacturer recommendations and monitor pressure drop to ensure consistent performance.

5. Control Combustible Dust Hazards

For aluminum, magnesium, or titanium dusts, adopt preventive measures aligned with IS 3595:2002 (Code of Practice for Fire Safety of Industrial Buildings – Dust Explosion Hazards).

• Avoid dry collection where ignition risk exists — use wet collectors.

• Ground and bond equipment to prevent static discharge.

• Maintain proper spark arrestors in duct lines.

6. Adopt Safe Cleaning Practices

Avoid dry sweeping or compressed-air cleaning, which can re-suspend fine particles. Use HEPA-filtered industrial vacuums or wet cleaning methods. Train workers to clean ducts, beams, and surfaces where dust may settle unnoticed.

7. Combine LEV with General Ventilation

LEV systems handle localized emissions; general ventilation manages background air quality and temperature.
Ensure there’s adequate make-up air to balance exhaust rates — preventing negative pressure that could disrupt airflow or reduce LEV efficiency.

8. Maintain Systems Proactively

Schedule regular inspection and maintenance of fans, ducts, and filters. Keep a preventive maintenance log as recommended in IS 14166 Appendix E.
Key checks:

• Fan bearings and impeller balance

• Filter differential pressure

• Duct leakage

• Hood airflow tests

9. Monitor Air Quality Regularly

Conduct workplace air monitoring following IS 5182 (Part 23):2006 – Methods for Measurement of Air Pollution. Compare results with exposure limits defined by Directorate General Factory Advice Service & Labour Institutes (DGFASLI) and Schedule XI of the Factories Act for permissible dust and fume levels.

10. Implement a Respiratory Protection Programme

When ventilation alone cannot control exposures, provide approved respirators as per IS 9473:2002 and IS 15323:2003 (Respiratory Protective Devices — Selection, Use, and Maintenance).
Ensure medical evaluations, fit testing, and worker training are part of the program.

11. Conduct Training and Awareness Programs

Train employees on:

• Hazards of metal dust and fumes

• Proper positioning of extraction arms

• Cleaning methods

• Use and maintenance of PPE

Keep training records as proof of compliance under Section 111A of the Factories Act.

12. Substitute or Enclose Processes Where Possible

Where practical, switch to wet cutting, low-fume electrodes, or robotic welding booths equipped with built-in extraction. Enclosures reduce emission spread and make LEV more efficient.