A fume hood creates a safer laboratory work environment by extracting and expelling dangerous fumes. There are basically two types of laboratory fume hoods: ductless and ducted hoods. Ducted hoods take the fumes from the laboratory through a system of internal building ducts to carry the contaminated air outside. A ductless hood has a built-in air recirculation system with a filter. Because it is not always possible to recirculate the laboratory air safely, ductless fume hoods are less common in laboratories using potentially harmful chemicals. However, ductless fume hoods have a few advantages over ducted hoods in that they can be installed in smaller laboratories that do not have access to preexisting ducts in the building. Ductless fume hoods are also cheaper to operate because they do not affect the temperature of the air in the room.
Both ducted and ductless types of fume hoods are designed to draw the fumes into the hood, where they are either carried through ducts and expelled outside or sent through an air purification system. In many laboratories, fume hoods can be considered essential equipment to meet workplace safety requirements. Fume hoods also ensure that the chemical vapors do not contaminate the workplace environment, disrupting laboratory results and experiments. Ductless fume hoods and fume hoods that divert the fumes through an air purification system may also be necessary to reduce toxic chemical emissions, either to help an organization reach its environmental ethics goals or to operate within legal emissions standards.
Fume hoods can also be designed to work in tandem with specific laboratory equipment. When laboratory equipment generates fumes, those fumes can be hazardous or flammable. Likewise, fume hoods can be designed to work with spill protectors and other laboratory accessories. Ducted fume hoods can be costly to operate because of the way they affect the temperature-controlled air within the laboratory, but they are often essential equipment.
