Work Practices for Laboratory Hoods
No large open face hood with a low face velocity and a work standing at the face of the
hood can provide complete safety against all events which may occur in the hood, nor for
volatile or otherwise airborne contaminants with a TLV in the low part per billion range.
For more ordinary exposures, a properly designed hood in a properly ventilated room can
provide adequate protection. However, certain work practices are necessarily in order for
the hood to perform capably. The following work practices are generally required; more
stringent practices may be necessary in some circumstances.
- Conduct all operations which may generate air contaminants at or above the appropriate
TLV inside the a hood.
- Keep all apparatus at least 6 inches back from the face of the hood. A strip on the
bench surface is a good reminder.
- Do not put your head in the hood when contaminants are being generated.
- Do not use the hood as a waste disposal mechanism except for very small quantities of
volatile materials.
- Do not store chemicals or apparatus in the hood. Store hazardous chemicals in an
approved safety cabinet.
- Keep the hood sash closed as much as possible.
- Keep the slots in the hood baffle free of obstruction by apparatus and/or containers.
- Minimize foot traffic past the face of the hood.
- Keep laboratory doors closed (exception: some of the laboratory design requires the
doors to be open).
- Do not remove hood sash or panels except when necessary for apparatus set-up; replace
sash or panels before operating.
- Do not place electrical receptacles or other spark sources inside the hood when
flammable liquids or gasses are present. No permanent electrical receptacles are permitted
in the hood.
- Use an appropriate barricade if there is a chance of explosion or eruption.
- Provide adequate maintenance for the hood exhaust system and the building supply system.
Use static pressure gauges on the hood throat, across any filters in the exhaust system,
or other appropriate indicators to insure that exhaust flow is appropriate.
- If hood sash is supposed to be partially closed for the operation, the hood should be so
labeled and the appropriate closure point clearly indicated.
If you have any questions concerning this list or the operation of a chemical fume
hood, contact the Occupational Safety and Health Division at 410.706.3490.
OSHA Link (Ventilation)
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