Polluted air in an industrial building may contain dry dust, fumes, oil mist, paint overspray, aerosols or vapours. These contaminants behave differently, so a suitable control strategy begins with identifying what is released, where it is generated and how the process operates.
The most effective solution is usually a sequence: capture the pollutant at source, transport it through a correctly sized duct network, separate or filter it with suitable equipment, and provide the air balance needed for stable operation.
Identify the pollutant before selecting equipment
- coarse chips and heavy dust may benefit from pre-separation before the final filtration stage;
- fine dry dust requires filter media and cleaning methods selected for its particle characteristics and loading;
- welding and thermal-process fumes need close source capture because they disperse rapidly;
- oil mist and machining aerosols require equipment designed for liquid droplets rather than ordinary dry-dust filters;
- paint overspray can be retained by dedicated dry or water-based stages, according to the process;
- vapours and odours require an assessment of the compounds and concentrations before an adsorption or other treatment stage is specified.
Capture at source whenever possible
A hood, extraction arm, bench, wall or machine connection should intercept the pollutant before it reaches the operator’s breathing zone or spreads through the hall. The geometry and airflow must reflect the direction and velocity of the emission. General room ventilation can support air balance, but it does not replace effective local extraction for a concentrated source.
Build the treatment train around the process
Industrial systems often combine several components:
- cyclones or other pre-separators to reduce the load of larger particles;
- bag or cartridge filters for suitable dry-dust applications;
- electrostatic or NO MIST equipment for appropriate oil-mist processes;
- Paint Stop or labyrinth filters for paint overspray;
- activated-carbon stages where adsorption is technically suitable for the identified vapours;
- fans, ductwork, gates and controls selected for the total pressure loss and operating pattern.
The collected dust or liquid must also be removed safely. Collection bags, bins, rotary valves, conveyors or other discharge equipment are selected according to the material quantity and handling plan.
Consider make-up air and room pressure
An extraction system removes air from the building. If replacement air is insufficient or poorly distributed, doors may become difficult to open, uncontrolled draughts may develop and capture performance can fall. Make-up air and, where required, heating or air-handling equipment should be assessed as part of the same design.
Evaluate fire, explosion and corrosion conditions
The material safety data, process temperature and ignition sources influence equipment selection. Combustible dust or flammable substances require a dedicated risk assessment and appropriate protection concept. Corrosive or wet contaminants may call for different materials and maintenance procedures from those used for ordinary dry dust.
Verify performance after installation
Commissioning should confirm airflow, branch balance, filter pressure drop, control operation and the behaviour of the process under normal simultaneous demand. These readings form a baseline for preventive maintenance and make future performance changes easier to diagnose.
See ALWO’s capture and filtration equipment or contact us with details about the pollutant, machines and working schedule.
