The secondary biosafety cabinet is divided into 4 levels according to the exhaust method.

Biosafety cabinets in Shanghai Xinzhuang are designed with high-performance filters on both the intake and exhaust systems to ensure maximum safety during laboratory operations. Among these, the first-class biosafety cabinet does not have an internal fan and relies entirely on an external air duct fan for airflow. However, due to its inability to protect the test samples or products from contamination, it is rarely used today. The second-class biosafety cabinet, on the other hand, is the most commonly used type in laboratories worldwide. It features an inlet airflow that enters through the front window, preventing aerosols generated during microbial procedures from escaping. Unlike the first-class model, the unfiltered air is captured by a pre-filter before reaching the work area, ensuring that the test samples remain uncontaminated. A key feature of the second-class cabinet is the downward laminar airflow, which is filtered through a HEPA filter and directed over the work surface to protect the samples from airborne particles. According to regulatory standards, second-class biosafety cabinets are categorized into four types based on airflow velocity, exhaust method, and air circulation: A1, A2, B1, and B2. All of them provide protection for the operator, the environment, and the test samples. For example, the A1 type requires a minimum airflow velocity of 0.38 m/s at the front window, with 70% of the air recirculated through the HEPA filter and 30% exhausted through the vent. The A2 type has a higher airflow requirement, with a minimum of 0.5 m/s and similar air distribution. The A2 model also creates a negative pressure zone around contaminated areas to prevent leaks. The B1 and B2 types are connected directly to the lab’s exhaust system. The B1 model recycles 30% of the air through a supply HEPA filter while exhausting 70%, whereas the B2 model operates as a fully exhausted cabinet with no internal air recirculation, making it ideal for handling hazardous chemicals and biological agents. The highest level of safety is found in the third-class biosafety cabinets, which are designed to handle level 4 pathogens. These cabinets are completely sealed, operate under full negative pressure, and require the use of gloves for operation—commonly referred to as glove boxes. Samples are transferred in and out via a double-door transfer chamber to maintain sterility and prevent contamination. Some A2 models come with an external drain pipe cover that includes an air intake hole. This allows the cabinet to draw air from the room without disrupting the internal airflow balance, which is essential when working with volatile chemical substances. However, this setup is only suitable for trace amounts of toxic chemicals. At Shanghai Xinzhuang, we specialize in manufacturing high-quality, safe, and cost-effective biosafety cabinets. Our commitment to excellence ensures that every product meets the highest industry standards. With years of experience and a focus on innovation, we are dedicated to providing reliable solutions for laboratories around the world. Trust us for superior quality and performance. Welcome to Shanghai Xinzhuang—where safety meets precision.

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