Laboratory fume hoods are a type of ventilation system with the primary function is to exhaust chemical fumes, vapors, gasses, dust, mist, laboratory hoods, SS fume hood and aerosol. Fume hoods also serve as physical barriers between reactions and the laboratory, offering a measure of protection against inhalation exposure, chemical spills, run-away reactions and fires.

A typical fume hood has a box like structure with a moveable sash window. Experimental procedures are performed within the hood which is consistently and safely ventilated, usually by means of an extract blower and ductwork. Chemical fumes exhausted and diluted many times over in the atmosphere and has a negligible effect to human health. When environment concerns are of importance, an extract treatment system, often referred to as a scrubber is installed to remove most of the vapors from the exhaust air stream.

The hood functions by maintaining a relatively negative pressure in the interior of the hood to prevent any contaminant from escaping while drawing air in through the hood opening at a consistent rate. A suitable hood face velocity (the speed at which air is drawn into the hood) is of importance to the safe and effective operation of a fume hood. While excessive face velocities can often result in turbulence and reduce containment, insufficient velocities can also compromise hood performance.

In general, a hood’s face velocity is recommended to be between 0.3 m/s (60 fpm) and 0.5 m/s (120 fpm), however it is important to check with local safety regulations on the face velocity recommendation before using the fume hoods.