ABSTRACT
The of chemical fume hoods is to personnel safety. It is a ventilated enclosure where hazardous materials can be handled. The chemical fume hood prevents contaminants from escaping into laboratory. This is accomplished by drawing fumes within the work chamber away from the worker so inhalation and contact are minimized. The concentration of contaminants in the
and the
zone must be kept as exceed the threshold
handled. The containment contaminants is on the principle
that a air entering at the hood through the exiting the exhaust port the escape of airborne contaminants from the hood into the room. The degree to which this is accomplished depends on the design of the hood, its installation, and its operation. There are three fume hood application levels:
In addition, there are several basic hood designs:
Many special purpose hoods are available. Among the most common special purpose hoods are:
Research technicians often use the term "hood" for other laboratory equipment that is similar in appearance to a fume hood, but are not considered fume hoods. These nonhoods include:
The location a chemical hood a lab is important. Generally, it should not be adjacent to the path of egress or heavy traffic area since explosions or fires are more likely at the hood, due to the activities being performed. It should be remote from cross drafts and air currents that could influence the hood velocity 8.4). Obviously, the hood should relate closely to the vertical shaft that contains the exhaust ducts to minimize horizontal duct runs.
