Typically consisting of a large enclosed, standing-height workspace with a sash-window front, fume hoods are a type of local ventilation device designed to protect workers from the hazardous materials they’re working with. Fume hoods achieve this feat by containing and removing fumes, gases, and particulate from the air, preventing hazardous materials from escaping containment, where they could potentially harm workers and contaminate the workplace.

There are two types of Fume Hoods: Ducted and Recirculating (or Ductless)

The way the two types of hoods operate is almost identical. A fan draws in air from the business end of the fume hood, providing the pressure needed to capture contaminated air and keep it from escaping. The big difference is what is done with the air afterwards, as Ducted Fume Hoods exhaust hazardous materials outside the building, whereas Recirculating Fume Hoods filter contaminated air, before recirculating it back into the room.

Ducted and Recirculating Fume Hoods each have their own advantages and disadvantages, allowing the proper choice for your industrial or laboratory process to be dictated by the needs of the user, the specifics of the workspace and the type of materials you’ll be handling.

Ducted Fume Hoods

Ducted fume hoods exhaust contaminants outside and should be considered when working with hazardous materials that produce high concentrations of contaminants, including chemicals that produce toxic gases or vapors, radioactive materials, and substances that may cause explosions.

The Benefits of Ducted Fume Hoods are as follows:

More effective removal of contaminants:

Ducted fume hoods exhaust the air outside through a duct system, which ensures that all contaminants are removed from the workspace. This is particularly important when working with hazardous materials that produce high concentrations of contaminants.

Safer work environment:

By removing contaminants from the workspace, ducted fume hoods help to create a safer work environment for laboratory workers and industrial technicians. This can help to reduce the risk of exposure to harmful substances and minimize the potential for accidents.

Greater flexibility:

Ducted fume hoods can handle a wider range of hazardous materials, including those that produce toxic gases, vapors, or particulate matter. This makes them a more versatile option for laboratories and industrial facilities that work with a variety of materials.

 Regulatory compliance:

Ducted fume hoods are typically required for compliance with local, state, and federal regulations governing laboratory and industrial safety. By using a ducted fume hood, you can ensure that you are meeting all relevant safety standards and avoiding potential penalties or fines.

Long-term cost savings:

Although ducted fume hoods may be more expensive to install initially, they can be more cost-effective over the long term. This is because they require less maintenance than ductless fume hoods and have a longer lifespan, reducing the need for frequent replacement or repairs. Additionally, they can help to minimize the risk of workplace accidents, which can result in significant cost savings over time.

Recirculating (Ductless) Fume Hoods

Ductless fume hoods recirculate scrubbed air after passing it through filters, and thus don’t require duct systems. While less effective than their ducted counterparts at removing gases or vapors, recirculating fume foods are quite good at removing particulate matter and can be used when working with less hazardous substances or when it is not possible or practical to install a duct system.

The Benefits of Recirculating Fume Hoods are as follows:


Ductless fume hoods are typically less expensive to install than ducted fume hoods, as they do not require ductwork. This can be beneficial for smaller laboratories or those with limited budgets.

Easy installation:

Since they do not require ductwork, ductless fume hoods are easier to install and can be moved around more easily if needed.

Greater flexibility:

Ductless fume hoods can be used in a variety of settings, including those where it is not practical or feasible to install ductwork. They are particularly useful in situations where there is limited space or where it would be difficult to run ductwork through walls or ceilings.


Ductless fume hoods typically use less energy than ducted fume hoods, as they do not need to constantly exhaust air outside. This can help to reduce energy costs and minimize the carbon footprint of a laboratory or industrial facility.

Lower maintenance:

Ductless fume hoods require less maintenance than ducted fume hoods, as they do not have ductwork that needs to be cleaned or maintained. The filters in ductless fume hoods can be easily replaced or cleaned, making maintenance relatively simple and cost-effective.


Ductless fume hoods can be customized with a variety of filters to meet specific needs, such as HEPA filters for biological hazards or activated carbon filters for volatile organic compounds (VOCs). This allows for greater flexibility in the types of materials that can be used in the laboratory or industrial setting.

In summary, if you’re working with hazardous materials that produce high concentrations of contaminants, a ducted fume hood may be the better option. But if you’re working with less hazardous materials or have budget or installation constraints, a ductless fume hood could be a viable alternative.

Are you looking to better protect your lab or facilities employees with the purchase of a new flow hood? Would you like to know more about the options available to you, including spill containment, upgraded lighting, airflow monitors, temperature & humidity controls, alarms, fire suppression systems and glove boxes?  Or maybe you’re looking to refurbish your lab, or design a new lab all together?

If so, give us a call at 908-541-1010 or click on the (contact us) button on the bottom of the screen. We are ready to answer your questions and discuss your needs.