It is usually kept under a negative pressure of approximately 0.5 inches of water. This is not a chemical fume hood. It is used for biological materials. Only small amounts of non-volatile chemicals can be used in these cabinets. The majority of hoods have one or two vertical sliding sashes, i.e., they move up and down.
Some hoods have three or more horizontal sliding sashes, i.e., they move left to right.
Atomic Absorption Spectrophotometer Exhausts. The University evaluates chemical fume hoods periodically to ensure that they are functioning appropriately. They also repair or replace faulty utilities, sashes and safety glass. The Division of Environmental and Occupational Health and Safety evaluates hood capture velocity and provides training to interested laboratory personnel regarding hood safety. However, if improperly used, even the best hood can be compromised beyond its capabilities.