Biosafety cabinet VAV or CAV

[martinakenic]

Hi to all,

I have a question regarding to laboratory biosafety cabinets. I know that fume hoods can be CAV (constant air flow) and VAV (variable air flow), and on internet have a lots of schematic how to control the air for laboratory room with few fume hoods , supply air , return air..
But Biosafety cabinets looks similar but i cant find what is recommendation , because we have few types, we have fan and hepa filters inside, do we need to separate every exhaust from bio safety cabinets ( i know that this depend from laboratory condition and test inside of cabinet ) , if is separate do we need CAV (i heard some people which says that only can be constant) , does bio cabinet works all night.. what happen if I shut down the cabinet is that mean that the exhaust fan will shut down?
On the internet I can find all types but i cant find how to control this cabinets , how to make exhaust system, do i need some control element on this exhaust system. What is recommendation and good practice.

Best Regards

Thanks

 

[SAK9]

Biosafety cabinets are constant volume devices unlike fume hoods and they need to be connected to the exhaust through a thimble connection. BSCs depending on the type allow recirculation of air as high as 70% unlike fume cupboards

 

[nglty]

depending on type of BSC. Check VA guidelines

https://www.cfm.va.gov/til/sDetail/Div11Equip/SD115353-02.pdf

https://www.cfm.va.gov/til/sDetail/Div11Equip/SD115353-01.pdf