A fume hood (sometimes called a fume cupboard or fume closet, not to be confused with extractor hood) is a type of local exhaust ventilation device that is designed to prevent users from being exposed to hazardous fumes, vapors, and dusts. The device is an enclosure with a movable sash window on one side that traps and exhausts gases and particulates either out of the area (through a duct) or back into the room (through air filtration), and is most frequently used in laboratory settings. The first fume hoods, constructed from wood and glass, were developed in the early 1900s as a measure to protect individuals from harmful gaseous reaction by-products. Later developments in the 1970s and 80s allowed for the construction of more efficient devices out of epoxy powder-coated steel and flame-retardant plastic laminates. Contemporary fume hoods are built to various standards to meet the needs of different laboratory practices. They may be built to different sizes, with some demonstration models small enough to be moved between locations on an island and bigger "walk-in" designs that can enclose large equipment. They may also be constructed to allow for the safe handling and ventilation of perchloric acid and radionuclides and may be equipped with scrubber systems. Fume hoods of all types require regular maintenance to ensure the safety of users. Most fume hoods are ducted and vent air out of the room they are built in, which constantly removes conditioned air from a room and thus results in major energy costs for laboratories and academic institutions. Efforts to curtail the energy use associated with fume hoods have been researched since the early 2000s, resulting in technical advances, such as variable air volume, high-performance and occupancy sensor-enabled fume hoods, as well as the promulgation of "Shut the Sash" campaigns that promote closing the window on fume hoods that are not in use to reduce the volume of air drawn from a room.
History
The need for ventilation has been apparent from early days of chemical research and education. Some early approaches to the problem were adaptations of the conventional chimney. A hearth constructed by Thomas Jefferson in 1822–1826 at the University of Virginia was equipped with a sand bath and special flues to vent toxic gases. The draft of a chimney was also used by Thomas Edison to provide ventilation in his work around the year 1900. In 1904 the newly built Faculty of Chemistry at the Technical University in Gdańsk was equipped with fume hoods made of wood and glass in auditoria, several lecture rooms, student laboratories and rooms for scientists. Vertical sliding front glass panels protected from fumes and explosions. Each fume hood was illuminated, equipped with gas for heating, and running water with a drain. Harmful and corrosive gaseous reaction byproducts were actively removed using the natural draft of a fireplace chimney. This early design is still functioning after over 110 years. The first known modern "fume cupboard" design with rising sashes was introduced at the University of Leeds in 1923. 13 years later, Labconco, now a prominent fume hood manufacturer, developed the first fume hood for commercial sale, reminiscent of modern designs with a front-facing sash window. Soon after, in 1943 during World War II, John Weber, Jr. developed a fume hood concept with a dedicated exhaust fan, vertically rising sash window, and constant face velocity in response to concerns about exposure to toxic and radioactive substances. This design would become standard among atomic laboratories at the time, and many aspects of his concept are incorporated in modern fume hood designs. The first mass-produced fume hoods were variously manufactured from stone and glass, most likely soapstone or transite, though stainless steel was being used by at least the 1960s. Labconco introduced the concept of a fume hood lined with fiberglass to improve durability and chemical resistance, though from the 1990s onward, epoxy powder-coated steel, teflon and polypropylene coatings were being recommended by literature for use in fume hood and exhaust construction.
Description
A fume hood is typically a large piece of equipment enclosing six sides of a work area (including a movable sash window or door), the bottom of which is most commonly located at a standing work height (at least 28 to 34 inches (71 to 86 cm) above the floor). Fume hoods are most often found in laboratories that require the use of materials that may produce harmful particulates, gaseous by-products, or aerosols of hazardous materials such as those found in biocontainment laboratories. Two main types of fume hood exist: Ducted and recirculating (ductless). The principle is the same for both types: air is drawn in from the front (open) side of the cabinet, and either expelled outside the building or made safe through filtration and fed back into the room. This method of airflow control is intended to:
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