What is the difference between a ducted and a ductless fume hood cabinet?

As a seasoned supplier in the fume hood cabinet industry, I've witnessed firsthand the diverse needs of laboratories and research facilities. One of the most common questions I encounter is the difference between ducted and ductless fume hood cabinets. In this blog, I'll delve into the intricacies of both types, highlighting their features, advantages, and limitations to help you make an informed decision for your specific requirements.

Ducted Fume Hood Cabinets

Ducted fume hoods, also known as exhausted fume hoods, are the traditional and widely used solution in laboratories. These hoods are connected to a building's ventilation system through a series of ducts, which expel hazardous fumes and contaminants outside the building.

How They Work

The basic principle of a ducted fume hood is to create a negative pressure environment inside the cabinet. When the fan is turned on, air is drawn into the hood through the front opening, carrying with it any fumes, vapors, or particles generated during the experiment. The contaminated air is then filtered and expelled through the ducts to the outside atmosphere, ensuring that the laboratory environment remains safe and clean.

Advantages

• High Efficiency: Ducted fume hoods are highly effective at removing hazardous substances from the laboratory. They can handle a wide range of chemicals and gases, making them suitable for most laboratory applications.
• Continuous Ventilation: Since they are connected to the building's ventilation system, ducted fume hoods provide continuous ventilation, ensuring a constant supply of fresh air to the laboratory.
• Compliance: Many regulatory agencies require the use of ducted fume hoods in laboratories that handle hazardous chemicals. Using a ducted fume hood can help you meet these regulatory requirements and ensure the safety of your laboratory personnel.

Limitations

• Installation and Maintenance: Ducted fume hoods require a complex installation process, including the installation of ducts, fans, and exhaust systems. They also require regular maintenance to ensure proper functioning, which can be costly and time-consuming.
• Energy Consumption: Ducted fume hoods consume a significant amount of energy, as they require continuous operation of the ventilation system. This can result in high energy bills and a negative impact on the environment.
• Limited Mobility: Once installed, ducted fume hoods are difficult to move or relocate. This can be a problem if you need to change the layout of your laboratory or move the hood to a different location.

For more information on ducted fume hoods, you can visit our Duct Fume Hood page.

Ductless Fume Hood Cabinets

Ductless fume hoods, also known as recirculating fume hoods, are a newer alternative to ducted fume hoods. These hoods use a filtration system to remove hazardous substances from the air inside the cabinet, and then recirculate the clean air back into the laboratory.

How They Work

Ductless fume hoods use a combination of filters, such as activated carbon filters, HEPA filters, and chemical filters, to remove contaminants from the air. When the fan is turned on, air is drawn into the hood through the front opening, passing through the filters to remove any fumes, vapors, or particles. The clean air is then recirculated back into the laboratory, providing a safe and clean working environment.

Advantages

• Easy Installation and Mobility: Ductless fume hoods are easy to install and can be moved or relocated easily. They do not require any ductwork or exhaust systems, making them a convenient option for laboratories with limited space or those that need to change the layout frequently.
• Energy Efficiency: Ductless fume hoods consume less energy than ducted fume hoods, as they do not require continuous operation of the ventilation system. This can result in significant energy savings and a reduced carbon footprint.
• Cost-Effective: Ductless fume hoods are generally less expensive than ducted fume hoods, both in terms of initial purchase cost and ongoing maintenance costs. This makes them a cost-effective option for laboratories with budget constraints.

Limitations

• Limited Chemical Compatibility: Ductless fume hoods are not suitable for all types of chemicals and gases. The effectiveness of the filtration system depends on the type of filter used and the specific chemicals being handled. Some chemicals may require specialized filters or may not be effectively removed by the filtration system.
• Filter Replacement: The filters in ductless fume hoods need to be replaced regularly to ensure proper functioning. This can be a hassle and can add to the ongoing cost of using the hood.
• Reduced Ventilation: Since ductless fume hoods recirculate the air back into the laboratory, they do not provide the same level of ventilation as ducted fume hoods. This can be a problem in laboratories that generate a large amount of fumes or require a high level of air exchange.

For more information on ductless fume hoods, you can visit our Chemistry Fume Hood page.

Choosing the Right Fume Hood Cabinet

When choosing between a ducted and a ductless fume hood cabinet, there are several factors to consider, including the type of chemicals you will be handling, the size of your laboratory, your budget, and your regulatory requirements.

• Type of Chemicals: If you will be handling a wide range of chemicals and gases, a ducted fume hood may be the best option. Ducted fume hoods are more effective at removing hazardous substances from the air and can handle a greater variety of chemicals. However, if you will be handling only a few specific chemicals, a ductless fume hood may be sufficient.
• Size of Laboratory: If you have a large laboratory with plenty of space, a ducted fume hood may be a good choice. Ducted fume hoods require more space for installation and maintenance, but they provide a higher level of ventilation and can handle a larger volume of fumes. On the other hand, if you have a small laboratory or limited space, a ductless fume hood may be a more practical option.
• Budget: Ducted fume hoods are generally more expensive than ductless fume hoods, both in terms of initial purchase cost and ongoing maintenance costs. If you have a limited budget, a ductless fume hood may be a more cost-effective option. However, it's important to consider the long-term costs of using a fume hood, including energy consumption and filter replacement.
• Regulatory Requirements: Many regulatory agencies have specific requirements for the use of fume hoods in laboratories. It's important to check with your local regulatory agency to determine the requirements for your laboratory. In some cases, a ducted fume hood may be required to meet these regulatory requirements.

Additional Considerations

In addition to the type of fume hood, there are several other factors to consider when choosing a fume hood cabinet, including the sash design, the airflow rate, and the noise level.

• Sash Design: The sash is the transparent window at the front of the fume hood that allows you to access the interior of the cabinet. There are several different types of sash designs available, including vertical, horizontal, and combination sashes. The type of sash you choose will depend on your specific needs and preferences. For more information on fume hood sashes, you can visit our Fume Hood Sashes page.
• Airflow Rate: The airflow rate is the amount of air that is drawn into the fume hood per minute. The airflow rate is measured in cubic feet per minute (CFM). The higher the airflow rate, the more effective the fume hood will be at removing hazardous substances from the air. However, a higher airflow rate also means higher energy consumption. It's important to choose an airflow rate that is appropriate for your specific needs and applications.
• Noise Level: Fume hoods can generate a significant amount of noise, especially if they are operating at a high airflow rate. If noise is a concern in your laboratory, you may want to choose a fume hood with a low noise level. Some fume hoods are designed with noise-reducing features, such as sound insulation and quiet fans, to minimize the noise level.

Conclusion

In conclusion, both ducted and ductless fume hood cabinets have their own advantages and limitations. The choice between the two will depend on your specific needs and requirements, including the type of chemicals you will be handling, the size of your laboratory, your budget, and your regulatory requirements. As a supplier of fume hood cabinets, we can help you choose the right fume hood for your laboratory and provide you with the support and service you need to ensure its proper functioning.

If you have any questions or need further information about fume hood cabinets, please don't hesitate to contact us. We are here to help you make an informed decision and ensure the safety of your laboratory personnel.

References

• American National Standards Institute (ANSI). (2016). ANSI/AIHA Z9.5-2016, Laboratory Ventilation.
• Occupational Safety and Health Administration (OSHA). (2012). OSHA Technical Manual (OTM), Section III: Chapter 6, Ventilation.
• National Fire Protection Association (NFPA). (2015). NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals.