Observation Chamber; Techni-Dome, 22" W x 22" D x 22" H, Bel-Art

Laboratory hoods serve a number of critical purposes in the lab environment.

Product protection from particulate contaminants in the lab environment, including microbes

这种引擎盖通常称为层流工作站或干净的长凳，使用大量的HEPA过滤空气来防止可行和不可行的颗粒流入封闭状态，并扫除工作过程产生的任何污染物。

Protection of personnel and lab environment from substances generated inside the enclosure

For fume containment, laboratory fume hoods use a ducted ventilation system that maintains negative pressure. Where ducting is impractical, ductless hoods are also available for removal of non-hazardous contaminants (fumes or particles), using either HEPA or activated carbon filters.

Protection of product, operator and environment

Biological safety cabinets combine aspects of both hood types: a laminar flow of micro-filtered air and negative-pressure containment of bio-hazard fumes.

Laminar flow hoods (also called laminar flow clean benches) force air through a HEPA or ULPA filter to create a clean work area free of nearly all contaminating particulates, including bacteria, mold spores and many viruses. These hoods use a vertical or horizontal airflow design. Both provide excellent protection of products from particulates and cross-contamination, but do not protect the operator or environment.

那么，为什么选择一个呢？垂直层状流动引擎盖（VLF引擎盖）需要更少的地板空间，但开销间隙更多。此外，VLF引擎盖前部的腰带在离开引擎盖和操作员的脸之间为空气提供了障碍。当空气撞击工作表面时，VLF引擎盖会产生湍流，需要在工作表面上方执行无菌工作。

HLF hoods minimize air turbulence (and particle backflow) on the work surface except where equipment disrupts the horizontal airflow. However, they direct the airflow directly at the operator’s face and require more depth to accommodate placement of the fan filter unit at the rear of the hood.

阅读有关水平和垂直层流罩之间的差异的更多信息

Laboratory fume hoods draw air from the environment through the opening of the hood, allowing environmental contaminants into the work area. Thus, lab fume hoods do not offer a sterile environment or product protection. Instead, chemical fume hoods are designed to protect the operator from dangerous or irritating fumes and powders generated from work performed inside the hood.

In ducted fume hoods and canopy fume hoods, air passes out of the hood through a duct leading to an in-house ventilation system that contains and/or neutralizes hazardous materials.

在无管的通风罩中，风扇通过一系列过滤器吸取了排气，这些过滤器会去除刺激性物质，然后再释放回房间。由于这些过滤器在去除所有物质方面并不是100％效率，因此在存在生物危害的情况下不建议无管烟发罩。但是，它们为无法访问内部HVAC系统的设施中的刺激性但无害的烟雾提供了方便，具有成本效益的解决方案。

Biological Safety cabinets combine design aspects of both laminar flow and fume hoods. Filtered air is directed downward onto the work surface and then travels into a plenum through openings on the front and sides of the hood. Depending on the classification of the biosafety hood, some percentage of air is recirculated through a HEPA filter while the rest is directed out of the hood through an exhaust system. Thus, biosafety cabinets offer operator, environmental and product protection.

这些实验室安全柜(有时称为IV hoods or compounding hoods) are ideal when preparing sterile medications such as chemotherapeutic agents that may pose a risk to the operator.

在使用危险或潜在的传染性材料时，保护人员必须是主要问题。但是，提供人员保护不必以冒着产品完整性冒险的成本。II类BSC同时为人员和产品提供保护。他们维护一个ISO 5级清洁工作区域进行产品操作，同时确保将排气空气过滤并从环境中进行管道。因此，当使用中等危险的材料以及人员和产品安全性时，II类BSC是理想的解决方案。

阅读更多about these lab hoods here regarding their biological safety rating