There should not be any turbulence at the hood face which could spill contaminated air into the room. All areas of the open hood face should have a velocity sufficient to draw room air and not spill contaminated air from the hood. These average face velocities and the date of survey will appear on the inspection sticker located on the front of the ventilation hood. All work involving hazardous chemicals should be performed inside a ventilation hood. Before work begins, check to be sure the hood fan is turned on.
Excessive storage can obstruct air flow and cause areas of low air velocity at the face opening.
Do not extend face or head inside the hood. When using electrical equipment in a hood take extra precautions to prevent spark sources from causing fire or explosion. All electrical connections should be made outside the hood. Do not use perchloric acid heated above ambient temperature in a ventilation hood unless it is a specifically designed perchloric acid hood with a wash-down system. Emergency plans should be understood by all hood users in the event of an unexpected occurrence such as fire or explosion in the hood.