The second class A2 biosafety cabinet is defined as the third class medical device in the medical de

The working principle of the two-stage A2 type biosafety cabinet: the air enters the negative pressure air duct from the front fresh air outlet and fully mixes with the air in the cabinet, then is sent to the static pressure cabinet by the fan. After being filtered by the filter, it enters the operation area in a vertical laminar flow state. The left and right sides of the operation area and the rear wall are negative pressure air ducts, so that the working area forms a double-layer isolation between the air curtain and the cabinet and the external environment. At the same time, the work area is surrounded by negative pressure to ensure that the sample does not leak. Due to the effect of exhaust fan, the air flow in the operation area mixes with the air entering the fresh air through the negative pressure air duct. Some of the mixed gas (about 70%) is sent to the plenum by the fan for recycling.

The cabinet body is air-tight and fully discharged, and all gases do not participate in the circulation. The staff operate through the gloves connected to the cabinet body, commonly known as Golve box. The test products enter and exit the safety cabinet through the double-door transfer box to ensure that they are not contaminated. If circulating chemical gases are not allowed, a type B2 secondary biosafety cabinet equipped with hard tubes must be used. Because the B-type safety cabinet is not an independent balancing system, its built-in fan can only produce downdraft, and the safety cabinet relies on the external exhaust fan to produce air intake. This type of safety cabinet will be complicated to install and maintain, because the external exhaust fan must be balanced with the internal fan, otherwise it will lead to the failure of the safety performance of the operator or the product.

Exhaust Collar type A2 secondary biosafety cabinet may be used under operating conditions that allow recycling of chemical gases. Discharge pipe cover and general hard pipe is different from the air intake can be inhaled; The discharge pipe cover is connected to the external exhaust pipe and then to an external exhaust fan. The intake hole on the discharge pipe cover is essential for the type A2 secondary biosafety cabinet to maintain the balance of intake and downdraft through the built-in fan. If the sealed external air duct is used, the air intake will be too strong, which may lead to the protection effect of the safety cabinet on the product; The intake hole on the discharge pipe cover can draw air from the room without affecting the air balance in the safety cabinet. This condition applies only to trace amounts of toxic chemicals.

The secondary A2 type biosafety cabinet is widely used in medical and health, food safety, biopharmaceutical and other fields. Its main function is to protect experimenters handling infectious experimental materials such as primary cultures, strains of bacteria and diagnostic specimens, and avoid the harm caused by infectious aerosols or spillages that may be produced during the operation. It can also protect the laboratory environment and experimental samples. It is an indispensable safety protection equipment in the laboratory. It is classified as three types of medical devices in the medical device classification catalogue.