Biological Safety Cabinets

Biological Safety Cabinets (BSC) are an effective piece of safety equipment when used, maintained and located properly.  The information presented on this site can help you with the proper selection and use of a BSC.

Click on the image for useful BSC information:

Biological Safety Cabinet Poster

Safety Cabinet Selection

The type of cabinet you will need is determined by the materials you plan to handle within the cabinet.  If you are unsure, please consult with the Biosafety Officer (8-5294).

For more information about selection of biosafety cabinets, consult the information provided by the Centers for Disease Control and Prevention.

Safety Cabinet Maintenance and Certification

The installation, certification, decontamination and maintenance of BSCs must be performed by certified professionals who can demonstrate accreditation by the National Sanitation Foundation.
Cabinets must be certified by NSF accredited individuals:
  • upon installation
  • after relocation
If a cabinet is in need of troubleshooting or repairs, ask your departmental safety manager for the name and contact information of the certification firm that has been contracted to maintain BSCs in your department.   Princeton University maintenance and janitorial staff should not be asked to conduct any type of service on a biosafety cabinet.
If a cabinet has been used for research involving potentially infectious agents or human-sourced material, it must be decontaminated by an NSF accredited professional  prior to repairs,  relocation or disposal.
To prepare your BSC for maintenance, certification or repair:
  • Empty the BSC of all items.  The cabinet must be completely cleared of any equipment, pipettes, waste, liquids and tubing.
  • Decontaminate the surfaces of the BSC with an appropriate disinfectant, such as a 10% bleach solution followed by 70% ethanol solution.
  • If you have scheduled a specific time for the maintenance to be performed, a lab member should be available to meet with the certification technician.

Working Safely in a Biosafety Cabinet

Preparing to work in the BSC

  • Wear appropriate personal protective equipment. Lab coat should be buttoned over street clothes and gloves should be worn to provide hand protection. Additional PPE may be used depending upon the outcome of a risk assessment.
  • Check certification sticker to confirm that BSC has been certified within the past 12 months.
  • Operate cabinet blowers for at least 5 minutes prior to starting work.
  • Disinfect cabinet surface prior to starting work.
  • Set the sash at the correct height, 8” to 10” depending on manufacturer’s guidelines.
  • Close the drain valve under the work surface prior to beginning work so that all contaminated materials are contained within the cabinet should a large spill occur.
  • Before beginning work, the investigator must adjust the stool height so that his/her face is above the front opening.
  • Set up your cabinet to reduce potential for contamination.  All materials must be placed as far   back in the cabinet as practical, toward the rear edge of the work surface and away from the front grille of the cabinet.

BSC set up

  • Aspirator suction flasks must contain an appropriate disinfectant, and a High Efficiency Particulate Air (HEPA) in-line filter.
  • All operations should be performed on the work surface at least four (4) inches from the inside edge of the front grille.
  • Active work should flow from the clean to contaminated area across the work surface.
  • Open flames (i.e., Bunsen burners) are rarely necessary in the near microbe-free environment of a biological safety cabinet and are an artifact left over from usage older model cabinets that only provided personnel protection.

Clean Up

Wipe-down  interior surfaces with the appropriate disinfectant.  Remove  gloves and gowns in a manner to prevent contamination of unprotected skin and aerosol generation and wash hands.

Protection of Vacuum Systems Used in Tissue Culture Work

The CDC/NIH Biosafety In Microbiological and Biomedical Laboratories, 5th ed., contains recommendations regarding protection of vacuum systems when working with biosafety level 2 materials.  The combination of disinfectant-filled flasks and an in-line filter protects personnel who service the equipment and the vacuum system from contamination.

Assembly of a Vacuum Flask System

Equipment Needed:

  • Two vacuum flasks, preferably plastic to avoid breakage
  • Thick-walled plastic tubing
  • Glass or plastic tubes
  • Rubber Stoppers
  • Filters:


Manufacturer's Part Number

Fisher Scientific Part Number

Vacushield Vent Device, Pall Life Sciences Part 4402  
Whatman HEPA-vent Filter 6723-5000 0974479
Millipore Millex Vacuum Line Protection





Vacuum Set-Up

Image published with permission from Weill Cornell Medical School , Environmental Health and Safety Department


Aspirator bottles or suction flasks should be connected to overflow collection flasks containing an appropriate disinfectant ( A and B)  and to an in-line HEPA (C) or equivalent filter before the vacuum line (D).  Note that the glass or plastic tube should be placed into the solution in flask B to minimize aerosols.

If the flasks are located outside of a biosafety cabinet, use secondary containment ( bin or tray) to contain spills if flasks are knocked over or in the event of breakage.


Fill the Aspiration Vacuum Flask with a disinfectant.  If using bleach, fill to about 10% of the flask’s volume. Keep in mind that when bleach and water are mixed together, the disinfectant qualities of bleach will degrade after 24 hours.    You will need to add additional bleach prior to disposal. Do not use alcohol due to flammability and disposal concerns.

Disposal of flask fluid

When flask (A) is approximately 75% full, it is time to disinfect and dispose of the fluid.   Add fresh bleach to achieve a 10% bleach solution.   If using other disinfectants, such as Wescodyne ©, add fresh product to achieve manufacturer’s recommended concentration. Stir the fluid and let sit overnight or at least one hour.    Dispose of the solution down the drain with plenty of cool water.


Change filter at least annually.  Dispose of expired filters into the regulated medical waste receptacle.

Use of Open Flames in a Biosafety Cabinet

The Centers for Disease Control and Prevention state that “open flames are not required in the near microbe free environment of a biological safety cabinet”.   Several major BSC manufacturers and the World Health Organization (WHO) recommended against the use of gas burners or alcohol flames within a cabinet.

Open flames:

  • disrupt air flow, compromising integrity of your research materials and protection of the worker.
  • result in excessive heat buildup, possibly leading to damage of HEPA filters.
  • present a potential fire or explosion hazard.
  • could inactivate manufacturer’s warranties on the cabinet.  In the event of a fire, explosion of worker exposure due to use of a flammable gas in the cabinet, cabinet manufacturers will assume no liability.

If you believe that you must use a flame inside the cabinet, consider these alternatives to continuous burning flames:

Bacticinerator for sterilization of loops and needles

Touch-O-Matic provides flame only when needed

Safety Lab Gas Burner: reduces airflow disturbances. Unit can be operated with touch-free DoubleClick IR-Sensor, button, or foot pedal.


UV Lights in Biosafety Cabinets

The Centers for Disease Control and Prevention (CDC) and the National Institutes of Health agree that UV lamps are not recommended nor required in BSCs.  Proper cleaning and disinfection using liquid disinfectant negates the need for use of UV lamps.

Please read the American Biological Safety Association’s position paper on the use of UV Lights in BSCs.