Other meanings of Fume hood
Laboratory Equipment
A fume hood (also called a fume cupboard or fume closet) is a ventilated enclosure in a laboratory that captures and exhausts airborne contaminants—such as toxic gases, vapors, and particulates—to protect the user and the environment. It is a primary engineering control for chemical safety, operating by drawing air through an adjustable sash and expelling it via ductwork or filtration. Fume hoods are distinct from biological safety cabinets, which filter air to protect samples and personnel from biological agents.
A fume hood consists of a work surface, an enclosing cabinet with a movable sash, and an exhaust system that draws air inward. The sash can be raised or lowered to adjust the opening size, which controls face velocity—the speed of air entering the hood. Typical face velocities range from 0.4 to 0.6 m/s (80–120 ft/min) for most chemical applications, but higher velocities are needed for highly toxic substances.1 The exhaust air is either ducted to the outside through a building's ventilation system or filtered and recirculated in ductless hoods. Baffles at the rear of the hood ensure uniform airflow and prevent dead zones where contaminants could accumulate.
Fume hoods are classified by construction and exhaust method. Constant-volume hoods maintain a fixed exhaust rate, while variable-air-volume (VAV) hoods adjust airflow to maintain a constant face velocity as the sash moves, saving energy. Ductless hoods use activated carbon or HEPA filters to remove contaminants and recirculate air, but they are only suitable for low-hazard applications. Standards such as ANSI/ASHRAE 110 and EN 14175 define performance testing methods, including tracer gas containment tests to verify that no fumes leak into the room.2 In the United States, OSHA and NFPA 45 provide regulatory guidance for installation and use.
Proper use of a fume hood is critical for safety. Users should keep the sash at the recommended height, work at least 15 cm (6 inches) inside the hood, and avoid rapid movements that disrupt airflow. The hood should never be used for storage of chemicals, as clutter can obstruct airflow and increase fire risk. Regular maintenance, including airflow monitoring and alarm systems, is essential. Fume hoods are not designed for protection against explosions or for handling radioactive materials without special modifications.3 Training in correct procedures is mandatory in most institutions.
The first modern fume hood is credited to J. W. Mellor at the University of Leeds in 1923, though earlier ventilated enclosures existed in the 19th century. Fume hoods are significant energy consumers; a single hood can exhaust as much air as a small house's heating system, leading to the development of energy-efficient designs like low-flow and auxiliary-air hoods. In the 1980s, the concept of 'fume hood density' became a metric for laboratory design, influencing building codes. Some hoods are equipped with wash-down systems for radioactive work, and others use perchloric acid–rated construction to prevent explosive residue buildup. The 'sash alarm' is a relatively recent innovation that alerts users when the sash is left open, reducing energy waste.
Fume hoods are a cornerstone of laboratory safety, yet their energy impact and specialized variants remain underappreciated.
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