VORTEX ll®
Bi-Stable Vortex Fume Safety Cabinet

VFVTM Fume Hood Control Makes VAV Obsolete
(Contd.)

Benefits

The fume hood's open sash hydraulic radius must be supported by the hydraulic radius of the chamber above the sash window opening. It is important that this chamber produce a bi-stable vortex which can expand and contract with sash movement. The internal dimensions of both depth and height of the vortex chamber are critical and must be designed to support the varying sash window openings. The present day fume hood totally disregards the size of the sash opening and these other critical dimensions.

The dimensions of the present day hood are determined by some manufacturers on their ability to walk through a door and be place on a bench, as if it were a kitchen appliance. Some manufacturers size their hood purely on maximizing the use of a 4 x 8 sheet of material, and others build the cabinet to the dimensions given to them by the specifying A & E. All of these hoods produce a weak mono-stable vortex. This mono-stable vortex collapses with sash movement, space pressure fluctuations, cross drafts, and activity in front of the hood. The robust, Bi-stable vortex found in the VFVTM fume hood, adjusts for such environmental conditions to maintain maximum containment.

Whenever a fume hood spills, it is because the vortex within the vortex chamber above the sash collapsed. The VFVTM control system's unique real time pressure transducer constantly monitors the vortex's stability and constantly repositions the internal baffle slots to compensate for hood loading, sash movement, space pressure fluctuations, cross drafts, and activity in front of the hood.

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