Laboratory hoods are a aggregate containment gadget and exhaust system. When the air in the lab hood is fouled with smoke or odor, the exhaust machine will vent the contained area and shield the room occupants. Sophisticated hood designs encompass furnish fans, utility outlets, hearth safety structures and variable-speed fan controls. If the chemical substances used in the laboratory are corrosive or volatile, unique building is necessary. Corrosion resistant alloys, spark resistant materials, exceptional motors and fan shaft seals are required.