Approval/Type
1. All cabinets must be NSF listed, UL approved, and installed in accordance with the manufacturer’s requirements.
Good Practice per Stanford University
Cabinets, which when used and installed properly, will provide both product and personnel protection. However, if the cabinet is not installed properly (e.g., not ducting a Class II, B2 cabinet), then it will not be serviceable. Installation of a cabinet which deviates from the listed NSF requirements, will void the NSF Standard 49 approved listing.
2. For Biosafety Level 2 applications involving toxic chemicals or radionuclides, a Class II- B type cabinet must be installed.
Good Practice per Stanford University EH&S
Class II-B cabinets do not allow in-room venting of exhaust air and are thus appropriate for such uses. For Biosafety Level 2 applications, fume hoods are not appropriate; a fume hood is not designed for the usage of biological materials. An appropriate biosafety cabinet must be used. The exact type of BSC should be specified early in the design process.
Venting
3. The Biosafety cabinet shall be vented from the building if toxic or malodorous chemicals are used. A thimble connection to the exhaust is one way to exhaust a Class IIA cabinet.
Primary containment for Biohazards, CDC/NIH
Good Practice per Stanford University EH&S
4. Venting to external ducts shall be monitored.
8 CCR 5142
Where cabinets are connected to external ducts, a flow monitoring system with audible and visual annunciations shall be used to alert the cabinet users of loss of external ventilation. Alternatively, thimble connections or canopy mini-enclosures in cabinets shall be fitted with a ribbon streamer or equivalent attached at an edge through which air enters the device to indicate the airflow direction.
Location
5. Biological safety cabinets (BSCs) must be located away from doors and other high traffic areas.
NSF Standard 49, Annex E, I.A.1
Good Practice per Stanford University EH&S
Currents of air can disrupt and degrade the protective capability of the cabinet. All attempts should be made to neutralize any interferences.
6. A biosafety cabinet should not be installed directly opposite of another biosafety cabinet if spatial considerations allow otherwise.
NSF Standard 49, Appendix E
Good Practice per Stanford University EH&S
Laminar airflow is greatly hindered by the operation of a biosafety cabinet located directly opposite of another biosafety cabinet or autoclave. It is recommended to provide at least six feet between cabinets.
7. A biosafety cabinet should not be installed directly under air supply inlets
NSF Standard 49, Appendix E
Good Practice per Stanford University EH&S
External air currents degrade the effectiveness of Biosafety cabinets. If possible, locate cabinets where air supply inlets will not interfere with performance
8. A Biosafety cabinet should not be installed within ten feet of an autoclave.
Good Practice per Stanford University EH&S
Exhaust from an autoclave may contain heat and moisture that will blow into the face of the cabinet. This will cause air turbulence in the cabinet and adversely affect the performance of the unit. There is also an increase of potential contamination within the cabinet if the autoclave is not functioning properly since the steam may contain spores or aerosols.
9. A 12-inch clearance should be provided behind and on each side of the cabinet to allow easy access for maintenance, and to ensure that the air return to the laboratory is not hindered. When the BSC is hard-ducted or connected by thimble unit to the ventilation system adequate space must be provided so as not to interfere with air flow.
Primary containment for Biohazards, CDC/NIH
Good Practice per Stanford University EH&S
These placement considerations are required to ensure maximum effectiveness of the primary barrier (BSC).
Natural Gas
10. Open flames are not to be used in Biosafety Cabinets
Good Practice per Stanford University EH&S
Stanford University has taken a strong stance against the use of gas burners or alcohol flames in Biosafety cabinets. The decision has been made in accordance with recommendations from numerous agencies. The Center for Disease Control and Prevention (CDC) reports that ‘open-flames are not required in the near microbe-free environment of a biological safety cabinet’ and create ‘turbulence which disrupts the pattern of air supplied to the work surface’ jeopardizing the sterility of the work area. This is also the recommendation of the World Health Organization (WHO) as well as the major Biosafety cabinet manufacturers.
Restraints
11. All biosafety cabinets must be provided with an appropriate means of seismic stabilization.
Good Practice per Stanford University EH&S
(Note: The manufacturer should always be consulted to avoid possible damage to the pressurized cabinet volumes.)
Autoclaves
12. Laboratory design must include an autoclave for sterilizing media, lab instruments, and medical waste as necessary.
CDC-NIH Biosafety in Microbiological and Biomedical Laboratories 5th Edition, Section IV – Laboratory Biosafety Level CriteriaSection, Biosafety Level 2 D. Laboratory Facilities (Secondary Barriers) -# 11
Guidelines for Research Involving Recombinant DNA Molecules (NIH Guidelines) Appendix G-II-B-4. Laboratory Facilities (BL2) App. G-II-B-4-f
An autoclave may be required since heat and pressure can kill potentially infectious spores that resist other disinfectants. The autoclave need not be in the actual lab room, however should be available in close proximity. All autoclaves shall be seismically anchored. All medical/biohazardous waste must be disposed in a manner consistent with the Stanford Biosafety Manual section on biohazardous waste.
