The Five Core Principles of Industrial Ventilation: A Guide to Safer Work Environments

Industrial ventilation system name it local exhaust ventilation system or general ventilation system is a critical component of occupational health and safety, designed to control workplace contaminants and protect workers from hazardous airborne chemical exposures. Whether managing aerosols (mist, fog 0.1-100 micron, particulate matter /dust, fibres, 0.0001-100 microns, smoke, fumes 0.001-100 microns), vapour and gaseous effective ventilation systems rely on a series of core principles. In this article, we’ll explore these principles in detail and explain how they contribute to a safer and healthier workplace.

1. Enclose the Contaminant as Closely as Possible

The first line of defence in controlling contaminants using the tenets of hierarchy of control is to prevent the escape of airborne hazards into the work environment. Enclosing the source of a contaminant reduces its spread and minimises worker exposure.

Why it Matters: Enclosures confine and contains airborne hazards close to their point of generation, making them easier to capture.

• Examples of Enclosure:

• Laboratory hoods.

• Fully enclosed machining systems.

• Spray booths for painting or coating applications.

By containing the airborne hazard, the emission of air impurities into the occupational settings will be eliminated reducing the overall burden of ventilation system to eliminate any airborne entering the breathing zone of a worker, leading to more efficient contaminant control.

2. Capture the Contaminant with Adequate Capture Velocity

Once contaminants are released, they must be captured quickly and effectively before dispersing into the workspace. This is achieved by maintaining proper capture velocity at the point of emission.

What is Capture Velocity? It is the air velocity required to draw contaminants into the ventilation system. The negative displacement of the ventilation system creates will create air displacement with the adequate intensity to MOVE the air into the hood conveying the airborne hazards together is part of movement. The range of capture velocity is subjective to :

• The energy of dispersion.

• The toxicity of the airborne hazards.

• The strength of cross draft caused by traffic, existing room draft, make up air and etc.

• Recommended Values: Capture velocities typically ranges from 75 to 2000 feet per minute subjective to the energy of dispersion (thermal, mechanical and chemical) depending not the process of airborne emission generation. Proper system design ensures that contaminants are captured efficiently, keeping the work environment clean and safe while being energy saving as high capture velocity does not necessarily means effective mitigate of exposure concentration. Effective selection of suitable hood which induces generation of homogenous flow is crucial for the capture velocity to do its job. 

3. Keep Contaminants Out of Workers’ Breathing Zone

What is breathing zone ?

Protecting workers from direct exposure is a fundamental goal of any ventilation system. Contaminants must be controlled in a way that keeps them out of their breathing zone—the space around the worker’s head where air is inhaled.

How to Achieve This:

• Use localised exhaust ventilation (LEV) systems which eliminates possibilities of airborne hazard entry.

• Position hoods or extraction points close to the source of contamination breaking the airflow path to the breathing zone.

• Optimise airflow to direct movement of air conveying the contaminants away from the workers breathing zones.

By designing ventilation systems with worker safety in mind, and understanding the full principles of the LEV system, companies can reduce the risk of respiratory illnesses and other health hazards. The selection of suitable hoods which fulfils the above mentioned needs, establishment of capture velocity based on dispersion energy and guiding the user the concept of LEV system will ensure high capture efficiency of airborne contaminant.

4. Supply Adequate Makeup Air

Ventilation systems remove air from a workspace, but this air must be replaced to maintain balance and ensure proper system performance. Supplying adequate makeup air is essential to avoid creating excessive negative pressure in the facility.

Why Makeup Air is Critical:

• Prevents backdrafting or the unintended flow of contaminants into occupied spaces due to extreme negative pressure. Significant amount of positive pressure can transfer contaminated air into adjacent enclosure.

• Maintains comfort and air quality for workers.

• Ensures ventilation systems work efficiently. Extreme negative pressure will create restriction of airflow into the exhaust fan causing the fan failing to meet the system design point of the system.

How to Supply Makeup Air:

• Install dedicated makeup air units to replace exhausted air by using the design room pressurisation and setting the right amount of pressure variance (10~15% recommended).

• Design systems to account for the volume and temperature of replacement air. Interface the air infiltration values with the AHU’s cooling load to the relevant AHU vendor. 

Properly balanced ventilation systems prevent operational inefficiencies and ensure a consistent flow of clean air.

5. Discharge Exhausted Air Away from the Inlet System

The air removed from a workspace contains hazardous substances, and its proper disposal is crucial to prevent recontamination. Exhaust air must be discharged far away from air intakes or occupied areas.

Best Practices for Exhaust Discharge:

• Position exhaust stacks at sufficient heights and distances away from the building envelope and wake region to form effective plume rise. Eliminate downwash which can increase ground level concentration of pollutants.

• Consider wind direction and local air dispersion patterns.

• Avoid short-circuiting, where exhausted air reenters the ventilation system increasing airborne hazards concentrations.

By safely discharging contaminated air, facilities can maintain a healthy environment and comply with regulatory standards.

Conclusion

Effective industrial ventilation is not just about installing fans or ducts—it’s about applying these five core principles to design systems that protect workers and maintain compliance with safety standards. By enclosing contaminants, capturing them effectively, protecting workers’ breathing zones, balancing airflows, and safely discharging exhaust air, businesses can create a safer and more productive work environment.

Investing in well-designed ventilation systems isn’t just a regulatory requirement; it’s a commitment to worker health and safety. By adhering to these principles, companies can foster a culture of care, reduce occupational risks, and enhance overall workplace efficiency.

Do you need help designing or optimising your ventilation system? Reach out to our team of experts to ensure your workplace stays safe and compliant!