Biosafety Cabinets

There are three main classes of Biological Safety Cabinets (BSCs).

  • Class I BSC provides personnel and environmental protection. It usually has an opening in the front below a sash where you can work with biohazards. Room air is drawn past the operator, past the product, and is exhausted through a single or dual HEPA filter to a dedicated exhaust duct or back into the room.
  • Class II BSC provides personnel, product and environmental protection. This is the most common type of BSC. It has an opening in the front where you reach in and work with the product like a Class I BSC. Unlike a Class I BSC, HEPA filtered air is supplied to the work area inside the hood allowing the BSC to provide product protection. Not only is the worker protected from the product, the product is protected from the worker. There are five types of Class II BSC that are differentiated in whether or not the exhaust air is vented to the room or ducted outside the building and how much air is recirculated within the BSC.
  • Class III BSC provides the highest level of personnel protection of the three classes of BSCs. A Class III BSC is a totally enclosed unit where access to the product is afforded by gloves attached to glove ports.


When people refer to biological safety cabinets, they normally mean a Class II BSC. Class II BSC manufacturers recommend certification at least once a year. NSF International supports a consensus standard (Standard 49) addressing Class II BSC design, construction, and performance, which requires certification at least annually. Different types of users may need to meet industry or regulatory certification requirements. The Joint Council of Accredited Hospital Organizations (JCAHO) recommends certifications at least annually for BSCs used in health care organizations. USP 797 requires Compounding Pharmacy’s BSCs to be certified semi-annually.

NSF International’s Standard 49 requires five containment tests for field certifications: downflow velocity profile test; inflow velocity test; airflow smoke patterns test; HEPA/ULPA filter leak test; site installation assessment tests; and cabinet integrity test (positive pressure plenum cabinets only). The four worker comfort and safety tests recommended by NSF International are: lighting intensity test; vibration test; noise level test; and electrical tests.

Class II BSCs are an important part of a biosafety program. With proper maintenance and service they can provide protection for many years. LTS Services, Inc. is uniquely qualified to execute a performance evaluation of your hood for certification, troubleshooting, repairs or general evaluation.

When LTS tests and certifies your contamination control equipment; such as a biosafety cabinet, you can be sure it will perform to appropriate standards or manufacturer specifications. We have been testing, certifying, and maintaining contamination control equipment since 1998.

We provide these services to a wide range of industries that use this equipment for research and production activities, including the pharmaceutical, health care, biomedical research, chemical, and biotechnology industries.