Correct use of
biological safety cabinets is an important part of laboratory safety operation and can minimize the risks to laboratory staff and the environment.
1. Placement
The air velocity entering the biological safety cabinet is about 0.45 m/s. At this rate, the integrity of the airflow is easily affected by factors such as the movement of nearby people, the opening and closing of windows, the opening and closing of doors, and the operation of air conditioners. To avoid interference from the above factors, the biological safety cabinet should be placed away from human activities, the flow of objects, and places that may disturb the airflow. For convenience, 30 cm of space should be left behind the safety cabinet and on both the left and right sides to facilitate the maintenance of the safety cabinet. 30 to 35 cm of space should be left at the top to accurately measure the speed of air passing through the exhaust filter and replace the exhaust filter.
2. Operators
When using a biological safety cabinet, the operator's arm should be inserted or removed slowly and perpendicular to the front opening to ensure the integrity of the airflow at the front of the safety cabinet. Operation should be started 1 minute after the hand or arm is inserted into the cabinet so that the safety cabinet can purify the air on the surface of the hand or arm. The equipment required for the experiment should be placed in the biosafety cabinet at one time, and the number of times the operator's hands enter and exit the safety cabinet should be minimized or limited.
3. Placement of experimental materials
The front opening of the Class II biosafety cabinet is strictly prohibited from being covered by paper, equipment or other items. After the items are placed in the biosafety cabinet, the surface should be wiped with 70% ethanol. A towel soaked in disinfectant should be prepared in the cabinet to absorb the splashed liquid. Experimental materials should be placed at the back of the cabinet as much as possible, and bulky items should be placed aside. Items that generate aerosols should also be placed at the back of the cabinet. Experimental equipment should be discharged in order from clean to contaminated. Contaminated experimental materials should not be taken out of the cabinet at any time, and the operator's hands should not frequently enter and exit the safety cabinet.
4. Operation and maintenance
Most biosafety cabinets are designed to be turned on 24 hours a day. Investigations have found that continuous operation is conducive to controlling laboratory dust and particles. Class II A can be turned off when not in use. Class II B should maintain laboratory air balance when in use, so if there are several operation processes in a day, the operation should not be interrupted during the period. The biosafety cabinet should be started 5 rain before the experiment begins to purify the local air. If any fault occurs during use, it should be reported to the superior in time and repaired by a full-time technician.
5. Ultraviolet light
Ultraviolet light is not required in the biosafety cabinet. If it is used, the lamp tube should be cleaned every week to remove dust and ensure the sterilization effect. The radiation intensity of the ultraviolet lamp should be monitored regularly. Prevent ultraviolet light from burning the eyes or skin.
6. Open flame
Open flame should be avoided in the nearly sterile environment of the biosafety cabinet. On the one hand, it can interfere with the airflow operation, and secondly, it will cause danger if volatile or flammable substances are used during the operation. If an inoculation loop is required during the operation, a disposable plastic inoculation loop should be used as much as possible. If a metal inoculation loop is used, it should be sterilized with a micro burner or electric furnace instead of an open flame.
7. Overflow
Everyone working in the laboratory should be familiar with the handling procedures for the overflow of samples containing microorganisms. Once a biohazardous item overflows in the biosafety cabinet, it should be cleaned up immediately while the cabinet is in working condition. Use effective disinfectants and minimize aerosol generation during the process. After the experiment is completed, all materials in the cabinet that come into contact with pathogens should be disinfected and sterilized.
8. Cleaning and disinfection
After the work is completed, all items in the cabinet should be cleaned of surface contamination and removed from the cabinet. The surface of the workbench and the inner wall of the cabinet should be disinfected with chlorine-containing lime (bleaching powder) or 70% ethanol. If corrosive chemicals are used for disinfection, sterile water should be used to scrub again. The machine should be run for 5 minutes before shutting down to purify the residual gas.
9. Decontamination
Before replacing the filter membrane, the biosafety cabinet should be fumigated with formaldehyde by professionals.
10. Personal protective facilities
Operators using biosafety cabinets should wear work clothes. People working in biosafety level 1-2 laboratories can wear ordinary work clothes; people working in biosafety level 3-4 laboratories wear reverse-back laboratory isolation gowns for better protection. Gloves should cover the protective clothing on the wrist joints. Some operations may require masks and goggles.
11. Alarm
The biosafety cabinet has the function of issuing one or two alarms. When the window frame moves, the alarm will sound, indicating that the operator has moved the window frame to an inappropriate place. The alarm will be lifted after correction. The airflow alarm indicates that the normal airflow operation mode in the cabinet is interrupted, the protection of the operator and the anti-contamination effect on the sample are minimized, and there is a danger. When the alarm sounds, you should stop working immediately and report to your superiors quickly. As a manufacturer, this content should be discussed in detail in the operation section of the product's instruction manual, and this content should also be included in the training materials for relevant personnel using biosafety cabinets.
For managers of medical laboratories, correctly selecting the type of biosafety cabinet, reasonably placing it, correctly using it, and annual certification is a complex but necessary process. These activities should be carried out under the guidance of experienced and well-trained experts. These experts should be familiar with relevant literature and have received training related to biosafety cabinets. As operators, they should receive formal training in operation, care, and maintenance before use.
