A fume hood (sometimes called a fume cupboard or fume closet) is a type of local ventilation device that is designed to limit exposure to hazardous or toxic fumes, vapors or dusts.

Standard Fume Hood

A standard fume hood is a constant air volume (CAV) hood, an older, traditionally less elaborate hood design used for general protection of the worker. Because the amount of exhausted air is constant, the face velocity of a CAV hood is inversely proportional to the sash height. That is, the lower the sash, the higher the face velocity. CAV hoods can be installed with or without a bypass provision which is an additional opening for air supply into the hood.

Bypass Fume Hood
The bypass fume hood is an improved variation on the conventional fume hood. The bypass is located above the sash face opening and protected by a grille which helps to direct air flow. The bypass is intended to address the varying face velocities that create air turbulence leading to air spillage. The bypass limits the increase in face velocity as the sash nears the fully closed position, maintaining a relatively constant volume of exhaust air regardless of sash position.

Auxiliary Air Hood

This fume hood, sometimes referred to as a makeup air fume hood, was developed as a variation on the bypass fume hood and reduces the amount of conditioned room air that is consumed. The auxiliary fume hood is a bypass hood with the addition of directly ducted auxiliary air to provide unconditioned or partially conditioned outside makeup air. Auxiliary air hoods were designed to save heating and cooling energy costs, but increase the mechanical and operational costs due to the additional ductwork, fans, and air tempering facilities. Unless the volume (and therefore velocity) of auxiliary air is carefully adjusted, the air curtain created will affect the hood operation and may pull vapors out of the hood interior. Installation of this type of hood is not permitted at OSU since the disadvantages outweigh the benefits.
 

Close The Sash
When an employee is not working inside the hood, the sash should remain closed.

Avoid Storing Chemicals In The Hood
Employees should never store any chemicals inside the hood when it is not in use. Chemicals should instead be stored in industrial furniture cabinets equipped to hold hazardous chemicals. However, large equipment can be stored in the hood as long as it is on top of blocks to allow air flow under the equipment.

Report Any Problems
Promptly report any issues you have experienced with the fume hood to a supervisor. It is important that a supervisor takes this fume hood out of service until it can be repaired to ensure the safety of employees.

What should do if accident accurs?

No one likes to think that an accident may occur. However, if it does, it is always better to be prepared and know what the proper response looks like.

The most important step to take in the immediate aftermath of a fume hood accident is its response. Take any and all actions to safeguard people working in the lab first and foremost. That may include putting out any fires, containing spills, evacuating the area, attending to the injured and contacting emergency services.

After the accident, an investigation must immediately begin. This will prevent important data from being lost and witness forgetting important details. By determining whether safety procedures were followed and whether equipment worked as it should have, new protocols can be put into place to prevent similar future accidents.