Working with Laminar Airflow
Laminar airflows are ventilation systems in a laboratory setup used to prevent contamination in the work space. They are available in forms of laminar flow hoods where the entire space has uniform velocity and direction. The hoods are designed with addition of advanced HEPA (high-efficiency particulate absorbing) filters that can trap even the tiniest particles like dust mites, pollen, or even tobacco smoke, and prevent the systems from all kinds of contamination. This kind of airflow system is used while working with biological samples or any sensitive materials.
The laminar airflow was first developed during 1960s when sir John Charnley saw a significant reduction in the infection rates during joint replacement implementations, using laminar airflow in the operating rooms. From then on, the laminar airflow has undergone certain configural modifications to fit the procedure requirements.
The laminar airflow is used in research, pharmacy, medical, electronic, educational, and plastic industries. It plays a major role in the processes where a clean and sterile environment is of critical importance.
Laminar Air Flow: How the system works?
Laminar airflows are used to create a sterile environment to conduct the experiments. The airflow system works in a uni-directional air stream that are regulated by advanced filters. The whole setup ensures to clean the air within the system to offer a space free from contaminants.
The laminar airflow cabinet, also known as laminar airflow hood or clean benches, is made of stainless steel. The hood consists of an open working space and the protecting glass that seals the system while allowing the user to see through. Laminar airflow works with the in-flow of air in a steady velocity and constant pressure, which is further drawn into two sets of filters, namely, pre-filters and HEPA filters. HEPA filters are the most advanced kind of filters that can trap particles of even 0.3 microns, with an efficiency of 99.97%, while pre-filters trap the bigger contaminants.
The hood is a basic work bench without any joints or hinges to avoid any bacterial build-up. The air is pushed in through air in-take fans which is sent to the filter systems mentioned earlier, and finally pushed in under constant conditions of speed and pressure. The air inside the cabinet is exposed to UV-light to sterilize it completely. The windows of the cabinet help in thermal insulation and also acts as an opening to work inside the space. The other components of the cabinet include glass shield and protection plate, which are placed to offer protection to the user.
Types of laminar airflow:
- Vertical Laminar Air Flow
- Horizontal Laminar Air Flow
These two configurations of the airflow are defined based on the direction of the airflow.
Vertical Laminar Air Flow: In this configuration, the air enters vertically onto the working space. The air than leaves the cabinet through the holes located at the base. They work on the principle of gravity; here the airflow coming from top sweeps the particles down and pushes them out of the system. Sometimes the particles also settle on the workspace, but they don’t linger around to contaminant the samples. Furthermore, the UV-light helps in killing any microbes present in the cabinet.
- Offers complete user protection as the air is not blowing directly
- Hood requires less floor space
- Since filters are on top, it is easier to use
- The chances of cross-contamination are negligible
- Less turbulent effect from air
Horizontal Laminar Air Flow: In the horizontal configuration, the air enters the system from the behind of the airflow bench. It is than sent to the filters in a horizontal direction to the working environment. The horizonal configuration requires huge operational space, otherwise, it might get difficult to work with. This kind of system may be often risky to work with, as the fumes or fine powder of the sample have chances of blowing the operator’s face.
- With larger operational space, they are easier to work with
- The vertical airflows cause turbulent effect as the air hits perpendicular to the workspace, such turbulent effects are eliminated while working with horizontal configuration
Based on the requirement, one can choose the kind of airflow systems with the specific configuration.
Working with Biosafety Cabinets
Biosafety cabinets are enclosed, sterilized, and ventilated workspaces that offer protection to the laboratory personnel and the environment from pathogenic microbes like the aerosols, accidental spills, and splashes.
Here the air from the cabinet is sent to HEPA filters to filter off any harmful microbes present in the air, before finally sending it to the exhaust. The major difference between Biosafety Cabinet and Laminar Air Flow is that unlike laminar airflow, where the air is filtered before sending in the cabinet, the biological safety filters air while sending out.
There are three kinds of bio safety cabinets namely Class I, II, and III. The uses of the them include:
Biological Safety Cabinets Class I
Biosafety cabinet Class I is the basic cabinet that is designed to offer protection to the personnel and the environment. Here, protection to the product is not offered as the unsterilized space is drawn on the work surface. The room air is drawn in the working space and then sent out by passing through the HEPA filters.
This cabinet is most suitable for working with chemicals and powders.
Biological Safety Cabinets Class II
The Class II biosafety cabinets provide protection to the environment and the personnel working on the sample. Here, the air is HEPA filtered to remove any microbes present in the air. The Class II cabinet, further, has five different types namely:
- Type A1
- Type A2
- Type B1
- Type B2
- Type C1
The requirements of each type are defined by the NSF international standards and used as per the requirement. It is to be noted that the Type A2 is the most popular ones and about 90% of the biosafety class II cabinets installed across the world are Type A2.
Biological Safety Cabinets Class III
The Class III biosafety cabinet are used in maximum containment laboratories. They are designed to work with Bio Safety Level – 4 pathogens, which have highest biosafety containment and easily transmitted through aerosol. The cabinet is enclosed in an air-tight environment and the materials enter and exit through double door autoclave. The cabinet is often custom-built to suit the laboratory requirements.
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