A chemical fume hood protects the user: it exhausts hazardous fumes and gases out of the room. A laminar flow hood protects the sample: it blows HEPA-filtered air over the work surface to prevent contamination. A Class II biosafety cabinet protects both and is used for biological material. The choice depends on what you need to protect: the person, the sample, or both.
A fume hood works under negative pressure: room air enters through the sash opening and is exhausted through a duct or a carbon filter. It is meant for solvents, acids and volatile chemicals. It does not protect the sample, because room air flows over it.
Ducted hoods connect to the building exhaust; ductless hoods use activated carbon filters. Ductless hoods are easy to install but only suit chemicals the filter can adsorb, and the filters need replacing.
A laminar flow hood pushes HEPA-filtered air in a uniform flow, horizontal or vertical, over the work surface, keeping the sample sterile. The air exits toward the user, so it must not be used with hazardous chemicals or pathogens.
A Class II cabinet combines both: downflow of clean air protects the sample, and an air curtain at the front opening protects the user. Exhaust air is HEPA-filtered. It is the right equipment for cell culture and biological work. The European standard for these cabinets is EN 12469; for chemical fume hoods it is EN 14175.
No. A laminar flow hood blows air toward the user, so chemical work needs a chemical fume hood.
Ducted hoods handle a wider range of chemicals. Ductless hoods are easier to install but only suit chemicals the carbon filter is rated for, and need filter changes.
Yes. Airflow testing and certification are done at the site where the hood is installed, so plan for them in advance.