Chemical Fume Hood Safety

A web version of the Drexel University Chemical Fume Hood Maintenance and Testing Policy can be viewed here. Portions of this document relating to Safe Work Practices and contact information for reporting Fume Hood Problems is reproduced below. A PDF version of the current Drexel University Chemical Fume Hood Maintenance and Testing Policy can be downloaded here.

Safe Work Practices for Laboratory Chemical Fume Hoods

No large open face hood with a low face velocity can provide complete safety against all events that may occur in the hood, nor provide protection for volatile airborne contaminants with a threshold limit value (TLV) in the low parts per billion range. For more ordinary exposures, a well-designed hood in a properly ventilated laboratory can provide adequate protection. However, certain work practices are necessary in order for the hood to perform capably. The following work practices are generally required; more stringent practices may be necessary under some circumstances.  

Conduct all operations that may generate air contaminants at or above the appropriate TLV inside a hood.

Keep all apparatus at least 6 inches back from the face of the hood. A stripe on the bench surface is a good reminder.

Users should keep their faces outside the plane of the hood sash.

Hood sash openings should be kept to a minimum. Hoods are tested (and should be used) with a hood sash opening of 15 inches.

Do not use the hood as a waste disposal mechanism except for small quantities (< 10 mL) of volatile materials.

Do not store chemicals or apparatus in the hood. Store chemicals in an approved safety storage cabinet.

Keep the slots in the hood baffle free of obstruction by apparatus or containers.

Minimize foot traffic past the face of the hood to prevent disruptions in air flow.

Keep laboratory doors closed when working in the hood.

Traps, scrubbers or incinerators should be used to prevent toxic and/or noxious materials from being vented into the hood exhaust system.

Do not place electrical receptacles or other spark sources inside the hood when flammable liquids or gases are present. No permanent electrical receptacles are permitted in the hood.

Use an appropriate barricade (e.g. a blast shield) if there is a chance of explosion or implosion.

Remain alert to changes in air flow.

Do not remove hood sash or panels except when necessary for apparatus set-up; replace the sash or panels before operating.

Exhaust ports from the hood and supply air vents to the room (Nesbitt units or unit ventilators) should not be blocked.

Prepare a plan of action in case of an emergency, e.g., a power failure.

To save energy, turn off the blower and close the hood sash when the hood is not in use.

Useful References

W.G. Mikell, W.C. Drinkard, "Good Practices for Hood Use", J. Chem. Ed., 61(1), A13-4, (1984).

W.G. Mikell, F.H. Fuller, "Good Hood Practices for Safe Hood Operation", J. Chem. Ed., 65(2), A36-7, (1988).

J.B. Adams, Jr., "Synthesis Laboratory Fumehoods", J. Chem. Ed., 66(12), A289-91, (1989).

G.T. Saunders, Upgrading Laboratory Fume Hoods", J. Chem. Ed., 64(11), A272-5, (1987).

G.T. Saunders, Upgrading Older Fume Hoods", J. Chem. Ed., 62(6), A178-80, (1985).

Rev. 1/25/99  kgo

A PDF version of the Fume Hood Safe Work Practices Notice can be downloaded here.

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Fume Hood Problems

Any problems with the operation of a hood should be reported immediately by contacting the Facilities Management Department directly, with follow-up contact with the departmental CHO and Safety & Health Department.

Mr. Henry McIlhenny, Facilities Management Department

tel: 215-895-2825, fax: 215-895-6754

Mr. Armour Floyd, Director, University Safety & Health Department

tel: 215-762-1098, fax: 215-762-7899

Dr. Kevin Owens, Departmental Chemical Hygiene Officer

tel: 215-895-2621

Hood Testing Procedure: All hoods are tested with a hood sash opening of 15 inches. A calibrated velometer is used to measure the hood face velocity in linear feet/minute (lfpm); the hood is considered approved for unlimited use if the average of 6 readings across the face is at least 80 lfpm and no one reading differs by more than 20%. Alternative testing methods and other information concerning fume hood safety and usage is contained in the Drexel University Chemical Fume Hood Testing and Maintenance Policy (revision 1/98).

Hood certification: Hood certification is performed annually (and after any repair) by the University Safety & Health Department. All preventive maintenance (scheduled quarterly) and repairs (when necessary) are performed by trained Building Engineers from the Facilities Management Department. All fume hoods need to be re-certified for use after repair. Questions concerning the status of the repair of a malfunctioning hood should be directed to Mr. Henry McIlhenny at Facilities Management (tel: 215-895-2825).

Rev. 10/1/01  kgo  

A PDF version of the Fume Hood Problem Contact Notice can be downloaded here.

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Copyright © 2002-2005, Department of Chemistry, Drexel University, All Rights Reserved.