Biological safety cabinet, fume hood, and ultra-clean workbench

A clear understanding of the distinction between biosafety cabinets and fume hoods/clean benches is required. Fume hoods and clean benches are not biosafety cabinets and should not be used in experiments or production processes involving microbial materials.

Biological safety cabinets (BSCs) are used to protect workers, laboratory environments, and laboratory products from the use of infectious experimental materials such as primary cultures, bacterial strains, and diagnostic specimens. Designed to be exposed to infectious aerosols and spills that may occur during the above operations. The Laboratory Biosafety Manual published by the WHO clearly states: “Biosafety cabinets can effectively reduce laboratory infections caused by aerosol exposure and contamination of cultures, and biosafety cabinets can also protect the working environment”. Of course, the premise of safe cabinet work is to purchase qualified safety cabinets and use safety cabinets correctly.

Fume hoods (ventilation cabinets) are designed to remove corrosive chemical gases and toxic fumes during chemical experiments. The fume hood does not effectively remove microbial media because it is not equipped with a HEPA filter. Microbiological samples placed in the fume hood will spread out of the cabinet and contaminate the laboratory environment.

The ultra-clean workbench (clean bench) is designed to protect the test piece or product. It prevents the test article or product from being contaminated by dust or bacteria outside the work area by blowing vertical or horizontal laminar air through the work area. Once the microbial sample is placed in the work area, laminar air will create a hazard by blowing air with microbial media to the front desk staff.

Attachment: Basic safety knowledge of biological safety cabinets and clean benches

Since most users are not very familiar with the performance, testing and testing of safety cabinets and clean benches, they have created a blind spot for these instruments. However, sometimes these blind spots can cause fatal injuries, such as laboratory virus leaks in Singapore, Taiwan and Beijing.

Whether it is a clean bench or a safety cabinet, it is not sufficient to rely on the wind speed to measure whether it is safe. Standard testing and certification rules guarantee the credibility of the inspection and the safety of the safety cabinet.

The current international standards for ultra-clean stations are:
Air cleanliness level in accordance with ISO14644.1;
Australian Standard AS 1807;
IEST-RP-CC002.2 standard.

Biological safety cabinet standard:
US ANSI/NSF49 (secondary safety cabinet);
European standard EN12469:2000 (first, second and third safety cabinets);

The clean bench can only protect the sample and does not protect the operator. The certification includes the following steps:
1) Measure the airflow rate of the clean bench with a rotating impeller anemometer and a heat anemometer. Average value of safe airflow: 0.4-0.5 m/s, maximum deviation 20%.
2) Measuring the integrity of the ultra-clean bench filter: using a natural aerosol tester.
3) Measure the internal light intensity and noise of the clean bench.

Biosafety cabinets are currently closely related to scientific research and are secondary biosafety cabinets and tertiary biosafety cabinets. Among them, the secondary biological safety cabinet can be divided into several categories, but the laboratory often uses 30% gas efflux, 70% gas circulation A/B3 type and 100% gas efflux type B2. The biosafety cabinet not only protects the sample but also protects the operator, so it becomes a "safe" cabinet. The detection steps are as follows:
1) Measure the inflow airflow (pre-intake airflow): Use a heat anemometer or a DIM airflow hood.
2) Measuring the downward airflow: There are two ways depending on the NSF49 and EN12469 standards. But both use a thermal anemometer to determine the downflow rate.
3) ULPA filter detection: aerosol photometer, aerosol generator, pressure gauge, PAO gauge.
4) There are also noise, light intensity, and vibration intensity measurements.
5) Finally, the smoke generator is used to test the airflow image.