4 questions to ask

Is my application supported by a ductless fume hood?

Considering the amounts and types of chemicals your lab uses is the first step in selecting an appropriate fume hood for your application. Ductless fume hoods are typically designed for moderate usage and are equipped with chemical filters designed to capture or neutralize specific chemical families such as organics, amines, acids, sulfurous compounds, and aldehydes. If your lab uses a variety of compounds, a blended filtration bed is also available. Blended filtration beds effectively adsorb a percentage of virtually every chemical; however, it is best to limit the number of chemicals used in a ductless fume hood to less than ten. Additionally, ductless hoods can also be equipped with HEPA (high-efficiency particulate air) filters to remove powders and particulates.

While most chemicals and applications are suitable for ductless fume hoods, there are some situations where your application may be best performed in a ducted fume hood. Applications that involve particularly high temperatures, such as acid digestion, are best avoided. Some organic compounds that are particularly lightweight and volatile (such as methanol) may be poorly captured by the filter and present hazards when used in large quantities. In addition, some chemicals present specific risks (e.g., perchloric acid, some radioisotopes) and require specific hood designs for safe handling.

How does switching from a conventional hood affect my budget?

The upfront cost of a typical ductless fume hood is often 3-4 times that of a conventional ducted hood. However, once you factor in the costs of the required infrastructure, including ductwork, mechanical systems, exhaust fans, and roof elements, the overall expense can be quite similar. If you are adding ducted hoods to your existing ventilation system, you will need an engineer’s evaluation to determine if your infrastructure can accommodate additional load. This may require the addition of a new or larger mechanical system at significant cost.

Airclean EndeavourAirClean Systems Endeavour Serieswww.AircleanSYSTEMS.comFume hoods also depend on large amounts of airflow, driving up the overall cost of HVAC sizing and energy usage for buildings with ducted hoods. In fact, for a standard 6-foot hood, the overall cost of operation can range from $4,600 to $9,300 per year depending on the local climate1. With upward of 750,000 fume hoods in use in the U.S. alone, the energy and cost saving potential is staggering. In fact, the operating cost of U.S. fume hoods has been estimated at approximately $4.2 billion dollars annually, with a peak electrical demand of 5100 megawatts1. It is easy to see how recirculating heated and cooled air back into the lab with a ductless system can quickly reduce energy usage and thus lower the cost of operation. With only filter replacement costs to consider (often in the rage of $350–$2,000 per year) labs can save thousands of dollars annually by switching to ductless fume hoods.

How does moving toward ductless technology support my needs for efficiency and flexibility?

Ductless fume hoods offer several advantages in terms of convenience and flexibility which begin at installation. When adding a new fume hood to your lab, consider that conventional fume hoods often have long lead times and require coordination with installation and building support staff. Your lab’s mechanical and HVAC systems may need to be upgraded or modified and the new system will require inspection and certification prior to use. Ductless hoods, on the other hand, arrive fully certified and ready to work out of the box. Should a fume hood require relocation, a ductless fume hood can easily be moved within the laboratory space, regardless of HVAC considerations without assistance from maintenance or engineering personnel. This added flexibility prevents downtime and allows the lab to adapt quickly to support new applications and requirements—saving time and money.

Do ductless fume hoods protect laboratory workers as well as conventional hoods?

Airsafe TouchAirClean Systems AirSafe Touch Controlswww.aircleanSYSTEMS.comDue to the fact that ductless fume hoods return filtered air to the lab, some believe that there is risk of chemical breakthrough, resulting in contaminants being released into the laboratory space. However, this simply is not the case. Modern ductless fume hoods have a long track record of safety and are equipped with sophisticated monitoring   systems that, when configured with the appropriate filter type, present minimal risk to laboratory personnel. In fact, condensation of solvents in building ductwork and buildup of flammable dusts from conventional fume hoods present a much greater risk to laboratory staff and have been the cause of numerous laboratory ductwork fires and explosions. Whether you are purchasing new hoods, upgrading your existing laboratory equipment, or planning new facilities, considering your ventilation options can help you select a solution that maximizes, safety, flexibility, and cost effectiveness.  While the many advantages of ductless technologies seem self-evident, remember that your ventilation solution should ultimately be chosen to ensure the safety of laboratory personnel. 


1. Mills, E. & Sartor, D. (2006) Energy Use and Savings Potential for Laboratory Fume Hoods. Lawrence Berkley National Laboratory Energy Analysis Department. Berkley, CA.