The Ductless Laboratory: Maximizing Safety, Flexibility and Cost Savings

Chemical fume hoods are typically the primary source of ventilation in laboratory facilities, helping provide a safe work environment for staff who handle hazardous or noxious chemicals. When deciding between conventional ducted fume hoods or ductless filtering fume enclosures, consider the following information.

Characteristics of Ductless Fume Hoods

• Ductless fume hoods are suited for moderate usage (three to four hours per day)
• They have chemical filters that capture or neutralize organics, amines, acids, sulfurous compounds, aldehydes, and other specific families of chemicals
  • If you use a variety of chemical compounds, it’s best to choose a mixed-bed filter
  • The number of chemicals should be limited to ten or fewer
• Ductless hoods may also have High-Efficiency Particulate Air (HEPA) filters to help remove powders and particulates

Characteristics of DuctedHoods

• Ducted hoods are useful for applications involving particularly high temperatures or for large quantities of lightweight or volatile organic compounds that may be poorly captured by filters
• Specialty hoods may be needed for applications with specific risks, like radioisotope and perchloric acid handling

Is my application suitable for a ductless fume hood?

✓	Ten or fewer chemicals are used
✓	No excessive heating required
✓	Limited chemical volumes (<500mL)
✓	Appropriate chemical filters are available
✓	Chemical exposure times are moderate (3 to 4 hours per day)

Budgetary Benefits of Going Ductless

A typical ductless fume hood can cost three or four times as much as a conventional hood, although the additional costs for modifying ductwork, mechanical systems, exhaust fans, roof elements, and other infrastructure may make the total expenses about the same. Adding ducted hoods to your existing ventilation system will also require an engineering evaluation. A new or larger system may need to be installed if your system cannot accommodate the additions.

The airflow required by ducted fume hoods can also add to overall heating, ventilation and air conditioning (HVAC) costs. In fact, for a standard six-foot hood, the overall operation can range from 4,600 to 9,300 USD per year depending on the local climate¹

With more than 750,000 fume hoods in use in the United States alone, the potential energy and cost savings is high. The annual operating costs total approximately 4.2 billion dollars, with a peak electrical demand of 5100 megawatts¹. Ductless systems allow conditioned air to be recirculated back into the lab, quickly reducing energy usage and lowering the cost of operation. Replacement filters for ductless hoods cost between 350 and 2,000 USD per year, another area for significant savings in comparison to standard hoods.

Efficiency and Flexibility

Ductless fume hoods offer convenient installation, while conventional fume hoods may require a long lead time and coordination with building support staff due to mechanical and HVAC upgrades and modifications. Your new system must also be inspected and certified prior to use.

Ductless hoods arrive fully certified and ready to use. They can also be placed in any laboratory space regardless of HVAC considerations and without assistance from maintenance or engineering personnel. This added flexibility minimizes downtime and allows you to adapt quickly to new applications and requirements.

Addressing Safety Concerns

Since ductless fume hoods route filtered air back into the lab, there may be questions about the risk of chemical contaminants being released into the space. Modern ductless fume hoods are equipped with sophisticated monitoring systems and are backed by a long safety track record. In contrast, solvent condensation in ductwork and the buildup of flammable dusts in conventional fume hoods can present a much greater risk, sparking fires and explosions.

Whether you are purchasing fume hoods, upgrading your existing laboratory equipment or planning new facilities, consider ventilation options that maximize flexibility and cost effectiveness and ensure the safety of your laboratory personnel.

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

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