Use of Biological Safety Cabinets
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Image compliments of The Baker Company |
A laminar flow biological safety cabinet is a valuable supplement to good sterile technique, but is not a replacement for it. To provide adequate protection, the cabinet user must understand and correctly operate the cabinet.
1. Ideally, the cabinet should be left running at all times. However, if it has been turned off, turn the blower switch to ON and before using it, let it run at least five minutes for room air to be removed from the cabinet. Make sure you have airflow by listening for blower sounds or by feeling the airflow with your fingers; also note that the magnahelic gauge reads in the proper range.
2. If your cabinet is equipped with a U.V. light, turn it off, and turn on the fluorescent light. Make sure the drain valve is closed.
3. The work surface, interior walls (not including the supply diffuser), and the interior surface of the window should be wiped with 70% ethanol (ETOH), a 1:100 dilution of household bleach (i.e., 0.05% sodium hypochlorite), or other disinfectant as determined by the investigator to meet the requirements of the particular activity. Remove residual chlorine by wiping the surface with 70% ETOH or sterile water. Similarly, the surfaces of all materials and containers placed into the cabinet should be wiped with 70% ETOH to reduce the introduction of contaminants. Further reduction of microbial load in materials to be placed or used in BSCs may be achieved by periodic decontamination of incubators and refrigerators.
4. After placing your equipment inside the cabinet, close the sash to the proper operating height (normally eight inches but on some cabinets, ten inches). Check the owners’ manual for proper height. Avoid working in and operating the cabinet with the sash in any other position than the manufacturers recommended sash height.
5. Wait another two to three minutes before working to clear all the contaminants from the work area.
6. Use proper personal protective equipment as a barrier to possible exposures and to reduce contamination of your research. Wear a lab coat, gloves, and eye or face protection, if appropriate.
1. Never operate a cabinet while a warning light or alarm is on.
2. The operator should be seated with the bottom of the sash level with his/her armpits.
3. Perform all work using a limited number of slow movements, as quick movements disrupt the air barrier. Try to minimize entering and exiting your arms from the cabinet, but if you need to, do it slowly, and straight in/out.
4. To avoid excessive movements in and out of the cabinet, discard pipettes into a tray, container, or biohazard bag within the cabinet.
5. Keep all materials at least four inches inside the sash opening.
6. Plastic backed absorbent toweling can be placed on the work surface (but not on the front or rear grill openings). This toweling facilitates cleanup and reduces splatter and aerosol formation during a spill.
7. All materials should 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. Similarly, aerosol-generating equipment (e.g., vortex mixers, tabletop centrifuges) should be placed toward the rear of the cabinet.
8. The general workflow should be from clean to contaminated (dirty). Materials and supplies should be placed in such a way as to limit the movement of dirty items over clean ones.
9. Activities that create eddy currents (opening and closing doors and windows, personnel walking near the cabinet), should be minimized as these types of activities can disrupt the air barrier.
10. Open flames in a biosafety cabinet create a fire hazard and can damage the HEPA filter. If it is absolutely necessary to use a flame, a touch-plate micro burner equipped with a pilot light or a micro-incinerator may be used. Place the burner at the rear of the work area where the air turbulence from the flame will have the least possible effect on the air stream. The burner must be turned off when the work is completed.
11. Aspirator bottles or suction flasks should be connected to an overflow collection flask containing appropriate disinfectant, and to an in-line HEPA or equivalent filter.
Completing Work in the Cabinet
1. All equipment that has come in contact with a biological agent should be decontaminated. The cabinet should be allowed to run for at least three minutes with no activity so that the airborne contaminants will be purged from the work area. Disinfect the surface of the equipment prior to removing it from the cabinet.
2. After all items have been removed, wipe down all surfaces of the cabinet with a disinfectant, including the sides and back, and the interior of the glass.
1. Cabinets should be placed away from doors, windows, vents or high traffic areas to reduce turbulence.
2. The cabinet exhaust should have a twelve to fourteen inch clearance from the ceiling for proper exhaust airflow. Also, allow a twelve-inch clearance on both sides of the cabinet for maintenance purposes.
1. Keep papers, paper towels, plastic backed absorbent toweling, vials, or any other objects from being pulled into the back, front, or side slots if no grill is in place to prevent this.
2. Do not store equipment or supplies in the cabinet.
3. Do not use the top of the cabinet for storage. The HEPA filter could be damaged and the airflow disrupted.
4. Do not place items on the front or rear perforated grills. This reduces the airflow.
5. Make sure the cabinet is level. If the cabinet is not, the airflow can be affected.
6. Never disengage the alarm, as it indicates improper airflow, thereby effecting performance and endangering the researcher or the experiment.
7. Never completely close the window sash with the motor running. This may cause the motor to burn out.
8. U.V. lights can accumulate dust and dirt that will block the germicidal effectiveness of the light. Clean U.V. lamps weekly to remove such build-up.
Your cabinet must be
certified upon installation, annually thereafter, and anytime it is moved (even
if just across the room). Biosafety cabinet certification is performed by the
Class II, Type A
BSC
Class II, Type B1 BSC
Class II, Type B2 BSC
Horizontal Flow "Clean Bench"
Updated February 21, 2006