A hood in laboratories are an effective means of capturing flammable, irritant, corrosive, carcinogenic vapors, etc. to prevent personnel exposures and avoid their dissemination in the laboratory atmosphere. When the hatch is down, the cab is also a physical barrier that protects the operator from hazards such as splashes, aerosols, fires, and minor explosions.
Fume hoods are a type of ventilation system with the primary function of protecting the user against exposure to chemical vapors, gases, dust, and aerosols. They function as physical barriers between reagents and the laboratory, offering protection against inhalations, spills of hazardous substances and fire.
A typical hood has a box-shaped structure with a movable window. The experiments are carried out inside the hood that is ventilated constantly and safely, usually by means of ducts. Chemical vapors are extracted and diluted many times in the atmosphere rendering them harmless to human health. If there are environmental concerns, a treated exhaust system can be installed to remove most of the vapors from the outside air stream.
It works by maintaining negative air pressures inside the cabin and preventing any air particles from escaping to the outside. The speed at which the air enters the hood is very important to guarantee the safety of the equipment. High speeds can create turbulence that will allow the air inside to escape, but low speeds may not be enough containment.