Ductless fume hoods are held to the same stringent regulatory standards as ducted fume hoods for operator safety and construction. In fact, in many cases ductless fume hoods exceed existing laboratory standards and requirements.

Face Velocity

The American National Standards for Laboratory Ventilation (ANSI/AIHA Z9.5-2003) states the required face velocity must be sufficient to capture and contain hazardous chemicals generated under “as-used” conditions.

Specifically, face velocities that operate within the range of 80-100 fpm provide adequate face velocity to evacuate the majority of hazardous chemicals, assuming proper containment characteristics throughout the rest of the ductless hood. Nearly all ductless fume hoods adhere to average face velocity of at least 100 fpm and are tested based on the best practice procedures outlined in ASHRAE 110 “Method of Testing Performance of Laboratory Fume Hoods.”

Face velocity in ductless fume hoods are typically indicated by a velocity monitor, flow alarm or face velocity alarm indicator, per ANSI/AIHA Z9.5-2003 requirements. Many models are now equipped with extremely advanced audible and visible alarms. Click here to learn more about advanced ductless fume hood alarm systems.


ANSI/AIHA Z9.5-2003 contains provisions for ductless fume hood filtration requirements as well, including section 9.3.1 for particulate contamination and 9.3.2 for vapors and chemical fumes contamination.

Ductless hoods are equipped with carbon filters and pre-filters that can be customized to a variety of chemical families. In addition, HEPA and ULPA filters can be incorporated to manage particulate contaminants for certain applications.

Learn more about ductless hood filters and the standards they adhere to by visiting Filtco Filters.

Carbon Filtration Efficiency

The efficiency of carbon filtration relates to how effectively a carbon filter is able to capture target contaminants from a ductless fume hood, while maintaining turbulence-free airflow in the hood. The air cleaning performance of ductless fume hoods must be evaluated to ensure proper filtration is taking place.

Chemical-specific detectors located downstream of adsorption media and pressure drop meters can help ensure effective contamination filtering based on existing TLV for known chemical families. Layered carbon filtration beds can provide protection from multiple chemicals at once. Learn more about layering carbon filters here.

Read more about application evaluations of ductless fume hoods or start a new evaluation of your application here.

Overall System

Ductless fume hood systems are held to stringent regulations based on ANSI/AIHA Z9.5-2003 standards and tested at ANSI/ASHRAE 110-1995 performance requirements. SEFA 1-2002, “Laboratory Fume Hoods Recommended Practices,” provides best practice ideas for ductless fume hood use in laboratory settings and distinguishes a set of operational standards for operators to ensure safe use practices.

NFPA45-2000 and CFR 29 Part 1910 provide additional regulations to which ducted and ductless fume hoods must adhere to ensure operator safety across a wide range of procedures.