1. All laboratory hoods are part of a mechanical exhaust system which is subject to failure. An
emergency plan, based on the type of work being done in the hood, should be prepared in case the
exhaust system fails. The emergency plan should be kept near the lab entrance door.
2. Hoods should not be considered ventilated storage cabinets. Any item placed in the hood will create
some turbulence in the hood or block airflow. Keep only those items necessary for the experimental
procedure in the hood enclosure.
3. Keep the sash closed when the hood is not in use. When using the hood, keep the sash at least
half closed to ensure proper ventilation and to provide eye and face protection.
4. Keep all work at least 10 cm. away from the front edge of the hood to allow proper ventilation.
5. Be aware of any warning devices located at the hood which monitor the hood's function. All new
hoods must have a direct reading instrument that indicates air flow velocity and that goes into alarm
if the airflow in the hood drops. Warning devices which are installed must not be removed or
6. Chemical fume hoods should have a face velocity of 80-100 fpm. Radiation fume hoods should
operate at about 125 fpm face velocity. If there are any questions concerning proper hood operation,
call Maintenance or OEHS. OEHS certifies hoods on an annual basis, or if there are problems.
7. Laboratory hoods are safety devices meant to contain and exhaust toxic, offensive, or flammable
materials. If there are any questions as to the use of a hood, please call OEHS.
8. Biological safety cabinets must be certified:
- after initial installation
- whenever they are moved
- on an annual basis.
The OEHS is able to provide this service at TUMC facilities for a minimal fee. The fee is based
uponthe type of unit involved.
9. Perchloric acid must be used only in those hoods designed and designated for that material. These
hoods are to be used only for perchloric acid. The interior of the hoods must be frequently cleaned
along with the ductwork; special washdown features are built into the ductwork for this purpose.
There is always a danger of explosion when using perchloric acid; be sure that all personnel are