Fume Hoods

How a Fume Hood Works

The complexities of hood operation become apparent when the many variables involved in exhausting fumes generated in the space are considered. First, there must be an adequate “pull” of air , known as face velocity, tomove fumes from the hood through the ductwork. Face velocity is measured in feet per minute (FPM) at the vertical sash plane. In order to maintain consistent face velocity, a certain quantity of air , or exhaust volume, is required. Exhaust volume is measured in cubic feet per minute (CFM). Sash position also impacts face velocity. The sash is a transparent panel set in the fume hood face, that provides access to the hood interior during set-up procedures and minimizes contact with dangerous chemicals and fumes during hood operation with the sash lowered.

Airflow patterns into the hood are influenced by the air foil.Located just beneath the sash, the air foil decreases turbulence of air entering the hood. (Some fume hoods feature air foils on the left and right sides of the sash as well).

Located across the inside rear of the hood, baffles control airflow patterns through the hood. Baffle panels are located in a position determined to be most effective for the application. A remote adjustment option allows the user to re-position the baffles according to characteristics of effluents generated in the hood.