Laminar flows are special devices that are used to regulate the flow of air in a particular velocity and in a particular direction. This is done to control the spreading of particles in the air that might contaminate the area. It is a form of sterilisation where the air itself is controlled so that the air-borne contaminants don’t go and contaminate other substances or the operator.
They help in creating particle free environment where the air, after it is pushed in a particular direction and given a particular velocity, is then sucked and filtered. They are also called Class 2 Biosafety desiccator cabinets and there are various types of them:
Type A cabinets: These are the cabinets in which the air is filtered and then recirculated back into the laboratory.
Type B cabinets:These cabinets do not recirculate back the air. They are connected to exhausts through which the contaminated air is expelled.
Type C1 cabinets: These cabinets are the hybrid of Type A and Type B and can be made to work either way
All of these cabinets have their air circulation inwards so that the contaminants are not blasted towards other people.
Then we have vertical and horizontal laminar flows.
Vertical laminar flows: In these cabinets, the air is circulated in a vertical direction. In this, the air is circulated from the top of the cabinet and sent to the bottom where the air then escapes through the holes in the base. This ensures that the airborne particles of the chemical substances do not reach the nose of the lab operators.
Horizontal laminar flows: In this type of cabinet, the air flows from the top, but then the direction of the air is changed and made to flow in a horizontal direction. This constant flow of clean air acts as an air shield for the substances underneath which prevents other pollutants in the air from from coming into contact with the protected substances.
Why are laminar cabinets important?
Laminar cabinets are important because they help in keeping a pollutant free zone so that the chemicals do not interact with air borne particles. This is very important for experiments which require an environment that is devoid of all other unwanted particles.
Another aspect of these laminar flows hoods is that they help in prevention of any turbulent air. This aspect is key for experiments where a chemical is required to have a uniform level of particle density all over its surface.
Difference between laminar flow cabinets and glove boxes
Although both of them are used to create an environment where experiments can be done without any external influence, there is a stark difference between the flow cabinets and the glove boxes. In a glove box, the air is allowed to be defused with the particles of substance that is being experimented upon to dilute the internal atmosphere of the glove box. Then the air is filtered out and its dilution rate is measured to determine how long we would have to wait before it’s safe to take out the substance inside. In this, the air inside is allowed to be diffused, which is not so in the case of air flow cabinets. The purpose of laminar flow is to simply keep the chemical substances free from any form of contamination.