Stanford University Fumehood Certification Program

Fumehoods at Stanford University are certified for use only if all of the following criteria are meet:

The average face velocity of the fumehood is 80 fpm or greater at a 15-in sash height.

All single-point velocity measurements are 70 fpm or greater at a 15-in sash height.

The centerline velocity measurement with the fumehood sash fully open is 70 fpm or greater.

Fumehood containment is shown using the ASHRAE 110 smoke test.

The operation of the fumehood is approved by the Stanford University Chemical Hygiene Officer (CHO) and all the above criteria are met. NOTE: Required only when the average face velocity at a 15-in sash height is greater than 400 fpm.

If the fumehood cannot meet all of the above criteria, the fumehood is posted and taken out of service.

Fumehoods can be operated over a range of average face velocities and still achieve containment, as demonstrated by the ASHRAE 110 smoke test. However, optimum containment provides the best possible protection to laboratory personnel. Therefore, fumehoods will be certified at a target average face velocity of 100-120 fpm and a minimum single-point velocity of 90 pm at a 15-in sash height. In addition, the target centerline velocity measurement with the sash fully open is 80 fpm.

NOTE: The optimum performance of a fumehood (optimum containment) is at 80-100 fpm. The target average face velocity of 100-120 fpm at a 15-in sash height was established to increase the likelihood that the average face velocity will not fall below 80 fpm during operation and to account for common use conditions.

If the fumehood has an average face velocity greater than 120 fpm at a 15-in sash height, and fumehood containment is shown using the ASHRAE 110 smoke test; the fumehood can remain in service. However, if the average face velocity is greater than 400 fpm, the certification results are reported to the Stanford University CHO. The CHO reports the certification results to the appropriate Heating, Ventilation, and Air Conditioning (HVAC) shop, Principal Investigator (PI), and University Safety Partner (USPer) and evaluates the fumehood performance with regard to safe operation at an elevated face velocity. If the CHO determines that the fumehood cannot be operated safely at an average face velocity greater than 400 fpm, the fumehood is posted and taken out of service, and the above parties are notified.

NOTE: At an average face velocity greater than 120 fpm, the optimum performance of the fumehood is degraded; however, if containment is achieved per the ASHRAE 110 smoke test, then the safety of laboratory personnel is maintained.

NOTE: At an average face velocity greater than 120 fpm, the additional volume of air flowing through the fumehood does not increase the protection provided to the laboratory personnel; however, it does add to the cost of operating the fumehood. For example, a 6-ft fumehood operating at 200 fpm with the sash fully open compared to one operating at 100 fpm fully open results in an additional, unnecessary cost per year of $5,400 per fumehood ($3.00/cfm/yr in 1999). If 10 fumehoods were operating in this manner within a building, the cost savings resulting from the fumehoods meeting the target average face velocity is $54,000/yr.

Stanford University Environmental Health and Safety (EH&S) oversights the safety criteria for inclusion into the standard operating procedure (SOP) for certification of fumehoods; however, the responsible HVAC shop produces, implements, and maintains the SOP for fumehood certification. The fumehood certification SOP is cosigned by the Stanford University CHO to show mutual agreement that the SOP contains the important certification criteria and meets regulatory requirements.