Streamline flow or laminar flow describes a distinct pattern of movement often utilized within a controlled environment, such as a lab. Lab personnel should be familiar with all of the necessary procedures involved with using a laminar air flow unit before doing any critical processes or handling bio-hazardous materials.
What is a Flow Hood Used For?
A flow bench orflow hoodprovides the proper sterile work area for many types of laboratory devices and is also used to avoid contamination of samples in PCR applications.
How Does it Work?
Sterile air is achieved by producing positive pressure in individual streams through a HEPA-filter in a parallel direction. This sterile, pressurized air is continuously blown over the hood which also minimizes turbulence within the hood’s work area.
What Makes a Flow Bench Effective?
- The effectiveness of a unit is determined by how well its air handling system and cabinet are engineered.
- It should be ergonomically friendly, easy to clean, and fabricated from materials that are durable, such as fully-welded stainless steel.
- A unit’s HEPA filtration should match a specific application’s requirements. Many applications call for flow benches that provide ISO 5/Class 100 HEPA-filtered air that can remove particulates and organisms 0.3 microns in size and have an air efficiency of 99.99%.
Classes of Flow Benches
Laminar flow units are designated as Class I, II and III, and have been developed to meet diverse clinical and research requirements. Class III hoods provide the maximum level of protection to the environment and lab personnel. They are required for work involving known human pathogens and other BSL-4 materials.
What Type of Unit Should Be Used?
The type of unit chosen is typically determined by the availability of space within a facility and on the work being done there. The flow of a hood can blow horizontally or vertically to the work surface. Vertical flow benches provide significant protection to both the user and the cell culture while horizontal flow benches provide protection to either the culture or the user based on its design.
Tips to Remember
- Do not store chemicals against the baffle at the rear of the hood since this will interfere with the laminar airflow across the bench. Also, do not place objects in front of the unit which can stop air flow and draw contaminants outside of the unit and into the room. Additionally, minimize foot traffic in proximity to the hood.
- Raise large equipment that must be kept in the fume hood 1.5 inches off the surface of the work space to allow air to circulate underneath it; this will increase the hood’s efficiency and greatly minimize turbulence. Other key things to remember when using flow benches are the following:
- Modifications to the fume hood should not be done without proper authorization.
- The laboratory staff should not block the laminar flow exhaust system.
- Keep the number of items on the working station of the hood to a minimum.
Controlling the movement of air using flow benches creates a more sterile lab environment. However, this equipment must be properly maintained to prevent the air in a lab setting from being contaminated. Therefore, excessive storage of chemicals and other items should be avoided since this will disrupt the designed airflow within the flow bench.