Category: Uncategorised Comments: 0 Post Date: 4th June 2025

Ducted vs Recirculating Extraction Units: Which System is Best for Labs, Schools & Educational Facilities?

ducted vs recirculating extraction units

Ducted vs. Recirculating Extraction Units: Choosing the Right System for Labs, Schools, and Educational Facilities

In environments such as laboratories, science classrooms, and vocational training centres, effective air extraction systems are essential for maintaining a safe and healthy atmosphere. Moreover, they are critical for protecting operators from harmful airborne contaminants. These systems are specifically designed to remove chemical vapours, particulates, and fumes, which can otherwise pose serious health and safety risks.

Among the various options available, two common types of extraction units are ducted and recirculating (or ductless) systems. Each comes with its own set of advantages, limitations, and ideal applications. In the following sections, we’ll explore the key differences and guide you through selecting the most suitable option.

1. Overview of Extraction Systems

Ducted Extraction Units

To begin with, ducted systems physically vent contaminated air outside the building through a connected ductwork system. Typically, the air is filtered before it is expelled, reducing indoor exposure to harmful substances.

Recirculating Extraction Units

On the other hand, recirculating systems—also known as ductless fume hoods—filter air internally and return it safely back into the room. These systems often feature multi-stage filters, including activated carbon for vapours and odours, as well as a HEPA,EPA or IFA filters for particulates.

2. Key Differences

Feature Ducted Units Recirculating Units
Air Discharge Expelled to atmosphere Cleaned and returned to the room
Filtration Basic pre-discharge filtration High-efficiency, multi-stage filtration
Installation Requires ductwork Freestanding; no ductwork needed
Mobility Fixed installation Portable or semi-portable
Running Costs Higher (energy loss from HVAC) Lower (but needs filter replacement)
Maintenance Duct checks, fan service, LEV Filter monitoring, LEV, timely replacement
Chemical Handling Broad range, high-volume use Limited by filter type and volume

3. Applications and Suitability

Ducted Systems are typically preferred in:

  • University and industrial labs handling volatile, corrosive, or toxic chemicals

  • Workplaces requiring high-volume extraction

  • Permanent installations with proper infrastructure

On the other hand, Recirculating Systems are ideal for:

  • School science labs using low-risk chemicals

  • Environments where structural changes are not feasible

  • Temporary or mobile setups

  • Buildings focused on energy efficiency

4. Pros and Cons Summary

Ducted Units – Pros

  • Handle a wide range of hazardous substances

  • Long-term reliability for frequent use

  • Compliant with stringent safety regulations

However, Ducted Units – Cons

  • Higher installation costs

  • Energy loss from expelling conditioned air

  • Fixed installations limit flexibility

Recirculating Units – Pros

  • Simple installation with no structural changes

  • More energy-efficient in climate-controlled spaces

  • Portable and flexible for evolving setups

That said, Recirculating Units – Cons

  • Not suitable for all chemicals (e.g., corrosives)

  • Require consistent filter monitoring and changes

  • Less effective in high-volume or heavy-duty scenarios

5. Regulatory and Safety Considerations

When choosing between these systems, it’s crucial to consider compliance with safety regulations, such as:

Importantly, compliance ensures user safety and may dictate system eligibility for specific environments.

6. Conclusion

Ultimately, the decision between ducted and recirculating extraction units depends on your facility’s needs. While ducted systems offer robust, long-term solutions for high-risk labs, they demand greater investment and fixed infrastructure.

Conversely, recirculating systems provide flexibility, efficiency, and ease of use—making them ideal for educational and temporary environments.

Therefore, consider the types of chemicals handled, volume of use, regulatory obligations, and space limitations. BenchVent can help you make an informed choice, ensuring you choose the right extraction unit for your process.

Want to learn more about ventilation standards?

Check out the COSHH guidance on Local Exhaust Ventilation for detailed safety requirements.

BenchVent can help you make an informed choice, ensuring you choose the right extraction unit for your process.

Explore our full range of ducted and recirculating fume cabinets to find the perfect solution for your workspace.

Contact our experts today. Let BenchVent help you build a cleaner, safer, and more productive workplace—one breath at a time.