The present COVID situation has presented with the most dangerous situation and it is important to use the best-in-line masks. We are talking about n95 masks that claim to filtrate 95% of particles. But is that true? So does all N95 masks filtrate 95% of particles? To know the answer you need to understand how a filtration process is conducted by N95 mask manufacturers. A good N95 mask manufacturer would always conduct a specific filtration process to make its N95 masks 95% effective.
The filtration principle of N95 masks
The filtration process implemented in N95 masks is seriously fibrous. And believe it or not, filter thickness does play a role in fixing the efficiency rate of a mask. And to be fully effective an N95 mask goes through a 4-stepped mechanism process to filter 95% of particles from the airstream. These are as follows:
1. inertial impaction
2. interception
3. Diffusion
4. Electrostatic filtration
Mechanisms
The pore size of the mask filters should be smaller than that of the particles that enter. But if it is too small then an individual will be unable to breathe. So these pore sizes should not cross a definite limit where a person can breathe comfortably as well as it filtrates efficiently too. And to meet this optimization level, these N95 masks are subjected to these mechanisms:
1. Inertial impaction: This mechanism is for larger particles where particles with larger inertia i.e. bigger mass or size will be diverted towards the filter fabric. These particles are so huge that they cannot follow the airstream at all.
2. Interception: The humongous particles when passing close to that of filter fabric, are intercepted by the filter fibre.
3. Diffusion: When small particles enter the air stream, they are constantly bombarded with air molecules, so they deviate from the airstream and come in contact with the filter fibre.
4. Electrostatic filtration: This mechanism is not dependent on the size of the particles. This mechanism follows the principle of attracting an oppositely charged particle towards a negatively charged filter fabric. This is a severe NIOSH-mandated procedure that, when followed, ensures that 95 per cent of efficiency and breathing resistance standards are met, as it improves particle collection without raising breathing resistance.
The 1st, 2nd, and 3rd mechanisms can be achieved by any of the masks available in the market but the 4th one is for special masks like N95 masks by the help of which it could efficiently filtrate 95% of particles from the airflow. Many of the best N95 mask manufacturers use this filtration process to produce good quality masks that have a very high demand in the market.
Electro-charged filtration in detail
To understand electro-charged filtration, you have to have a close look into the concepts of physics where people living in cold climatic weather conditions usually wore warm clothes. And these warm fabrics when rubbed against each other gain static electricity. So the separately charged positive and negative surfaces stick to each other. This is what happens in the N95 masks where different types of fabrics are used to create N95 masks, where when rubbed create static charge and sticks to each other. Electrospun polymer is the main fabric used in the N95 masks.
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