The body of the daily respirator is made of filter material.The wearer overcomes the resistance of the filter material to the airflow by self-breathing, so it is called self-suction filter respirator.On inhalation, the low pressure in the mask causes air to enter the mask;On exhalation, the air pressure in the mask is higher than the ambient pressure, and the air flow is discharged through the mask.When the filter material of the mask meets the standard requirements and the mask is close enough to the user's face, most of the inspiratory air will be filtered out by the filter material.The daily use of protective masks can not be 100% close to the face, which is affected by the shape of the face, the smoothness of the skin, whether there is hair under the mask and other factors.Most of the particles inhaled by daily respirators come from leakage, so the strictness of daily respirators is the key to ensure the effective work of filter materials.To reduce leakage, daily protective masks must be designed with a human body structure, with the headband and nose clip applying some pressure to keep the mask close to the face.
Materials used to filter particulate matter include mineral fiber, natural fiber or synthetic fiber.There are five types of fiber filters that filter particles from the air and work together.
Settlement: the large particles in the airflow settle on the filter material under the action of gravity and are separated from the airflow;
Inertial impact: When the particles in the air flow bypass the filter fiber in front of the air flow, the particles with higher mass will deviate from the direction of the air flow due to inertia and collide with the filter fiber to be filtered.
Interception: the particles are located on the streamline closest to the filter material in the airflow. Because the particle radius is greater than the distance between the streamline and the filter material, the particles are intercepted by the filter material "scratch".
Diffusion: Due to the thermal movement of air molecules, extremely small particles are impacted by air molecules, constantly changing the direction of motion, showing Brownian motion, and randomly contacting the filtered filter fibers.
Electrostatic effect: If the filter fiber has weak static electricity, whether the particles in the airflow are static or not, when they are close to the filter fiber, they are easy to be attracted by static electricity and filtered out.Electrostatic effect can help filter material to improve filtration efficiency without increasing air resistance.
The healthy public is not advised to wear masks in daily life and normal social activities.Wear a mask for personal protection if you need to come into contact with people with infectious diseases or if you spend a long time in crowded, poorly ventilated places.