Patent ID: 7470176

Claim:
A stable vortex fume hood converted from an existing fume hood having a front face with an access opening into a working chamber and a vortex chamber above the working chamber comprising: i) an exhaust system connected to the fume hood including a fan and an exhaust duct; ii) a rear baffle conduit connected to the exhaust system; iii) a vortex bypass conduit adjacent the front face of said fume hood and connected to the exhaust system; and iv) a means for dynamically controlling the amount of air flowing through the vortex chamber by variably bypassing air though one or both of the rear baffle conduit and vortex bypass conduit, wherein the vortex bypass conduit is formed with a vortex chamber turning vane that is adjustable and positioned at an angle in accordance with an Effective Reynolds number to sustain a stable vortex in the vortex chamber.