A fume hood, fume cupboard, or just hood device common to chemistry laboratories designed to keep hazardous fumes out of the room air by exhausting them out of the building before anyone can potentially breathe them.
Fume hoods are generally available in 5 different widths; 1000mm, 1200mm, 1500mm, 1800mm and 2000mm. The depth varies between 700mm and 900mm, and the height between 1900mm and 2400mm. These can accomodate from 1 to 3 operators. They are generally set back against the walls and are often fitted with infills above, to cover up the extract ductwork. Because of their shape they are generally dim inside, so many have internal lights with gas-proof covers. The front is usually glass so you can see into it and able to move up and down.
If the hood is working properly, a constant air flow is created through the device, usually using fans, exhausting the air inside it through the top of the fume hood and out of the building or through a decontamination process if the fumes can't be released to the open air (for instance, vinyl chloride).
To determine whether a chemical is likely to require a fume hood for safe usage, its MSDS should be consulted. If there is doubt, use a hood.
Even though a properly functioning fume hood provides adequate ventilation be sure not to directly smell any chemicals directly even when using one. Doing this could cause severe damage to your trachea and lungs. Instead take your palm and wave it above the test tube or beaker to waft reduced amounts of the substance towards your nose.
