Research labs typically have a chemical fume hood or a biosafety cabinet as the primary engineering control. However, there are an assortment of task-oriented engineering controls to choose from when deciding which control is safest for the task at hand. A risk assessment should be conducted to determine the proper control. Below is a list of local exhaust systems and containment devices for consideration.
Glove Box
Controlled work environment.
Enclosure that is typically used when there is a need for an oxygen-free atmosphere.
User performs tasks by inserting hands into sealed gloves built into the front of the enclosure.
Protects the user, the environment, and/or the product being used. Reactive chemicals are often used and stored in glove boxes.
Does not exclude the user from having to wear appropriate personal protective equipment.
Snorkel Vent or Fume Extractor
Extracts fume or particulate away from the user's breathing zone if used correctly.
Also called elephant trunk or flex duct. Recommended for soldering, light grinding, working with pharmaceutical powders, and/or during animal surgeries where backdraft or downdraft tables are unavailable or impractical.
May be ordered with a flexible or rigid arm.
Depending on its use, a snorkel can be purchased with:
- no filter,
- a HEPA filter, and/or
- a carbon filter.
User must work very close (4-6 inches away) from the end of the snorkle (the flange) in order to have appropriate capture of the fume or contaminant.
Often used improperly and without training.
Ductless Hood
A ventilated enclosure that has its own fan(s). The fan(s) draws air out of the enclosure through HEPA, ULPA or carbon filters and recirculates the filtered air back into lab
Can only be used with limited types and amounts of dilute chemicals. Filter efficiency decreases over time, which may cause chemicals to desorb from the filters. Often use alot of energy.
UVM recommends against the use of ductless hoods, as ducted chemical fume hoods are better designed to reduce exposures.
Downdraft Table
Draws contaminants down and away from user's breathing zone without hindering user's movement or productivity. Highly effective at removing contaminants with low vapor densities since these types of hazardous vapors will more readily be drawn downward.
Downdraft tables can either be connected to building exhaust system or be installed as a stand alone unit with filters that are designed to capture specific vapors from limited amounts and types of chemicals.
Backdraft table
Uses a negative air source to pull air, odors, vapors or aerosols back and away from the user's breathing zone and into a perforated or slotted exhaust panel(s) on the back of the table or station.
Backdraft tables can either be connected to the building exhaust system or be installed as a stand-alone unit with filters that are designed to capture specific vapors from limited amounts and types of chemicals.
Often used for animal surgery or necropsy stations.
Slot Ventilation
Designed to draw contaminants away from the user's breathing zone and into slot vents.
Slots must be at the proper height and positioned less than 4 inches away from the contaminant in order to capture.
Often used in photography developing areas or for mixing dry ceramic glazes.
Less common local exhaust and containment devices used on campus include:
- biobubble
- dust filtration devices (wood shop and soil science labs)
- anaerobic chamber
- weighing chamber for fine particulate
- paint spray booth