Biological safety cabinet

A bio-safety cabinet comprising:

• an all metal frame defining an upper housing on top of a lower protected work chamber, said upper housing fitted with a combination of exhaust and downflow ULPA filters and a blower sealed within said upper housing to provide air inflow and air downflow into said work chamber, air outflow out of said work chamber, said upper housing having a front panel and said work chamber being enclosed on all sides and a back and having a front opening for work access into a work zone inside said work chamber for the performance of general microbiological work within said work zone, a slidable glass sash coupled to said frame, said sash movable to at least partially close said front opening for work access, and a microprocessor control and alarm system, and a plurality of downflow sensors positioned at multiple locations within said cabinet for detecting the downflow velocity of said air downflow and providing the results of said detection to said microprocesser, wherein said microprocessor determines the average of said detection results.