Summary of knowledge related to air filters

1 , ULPA

Ultra-high efficiency air filter Or called an ultra-low penetration air filter, the filtration efficiency MPPS for dust particles such as 0.1~0.2μm particles, smoke and microorganisms is greater than 99.9995% span>.

2. HEPA

High-efficiency air filter, for particles with a particle size of 0.3μm, the filtration effect is about DOP 99.97% or more;MPPS reaches 85% – 99.995%, and the EN1822 standard level is level H.
3. High efficiency filter

High-efficiency filters are mainly used to capture particle dust and various dust particles above 0.5um Suspended solids, as the end filtration of various filtration systems. Each unit has been tested by the flame method and has the characteristics of high filtration efficiency, low resistance, and large dust holding capacity. Used to separate: tiny contaminants such as bacteria, viruses, carbon black and radioactive particles. High-efficiency air filters can be widely used in the air supply terminals of air-conditioning in dust-free purification workshops in industries such as optical electronics, LCD liquid crystal manufacturing, biomedicine, precision instruments, beverages and food, PCB printing and other industries. High-efficiency and ultra-high-efficiency filters are used at the end of the clean room. Their structural forms can be divided into: high-efficiency filters with partitions, high-efficiency filters without partitions, high-efficiency filters with large air volume, ultra-high-efficiency filters, etc.

4. Medium efficiency filter

Medium-efficiency filter belongs to the F series filter among air filters. F series medium-efficiency air filters are divided into bag type and non-bag type. Bag type includes F5, F6, F7, F8, F9. Non-bag type includes FB (plate type medium efficiency filter), FS (partition type medium efficiency filter). filter), FV (combined medium-efficiency filter).
5. Primary filter

Primary filter is usually the primary filtration device of the filtration system, which can prevent the high-quality fine dust filter from being blocked or damaged by coarse dust. Mainly used to filter dust particles above 5μm. For the separation of: coarse dusts such as bugs, textile fibres, hair, sand, airborne dust and pollen. There are three types of primary filters: plate type, pleated type, and bag type.

6. Pressure drop

The pressure difference between two points upstream and downstream of an air filter carrying airflow. Also called resistance or differential pressure.
7. MPPS

Easiest to penetrate particle size, can penetrate air filters The maximum particle size of the filter material. Compared to smaller particles, MPPS penetrates HEPA filters more easily (less susceptible to cyclones and van der Waals forces). In other words, the filtration capacity of HEPA for MPPS is 99.97%, and the filtration capacity for smaller particles than MPPSP may be 99.99%. There are misunderstandings in our previous understanding of HEPA filters.

8. Supplementary knowledge points

Dust particles smaller than 1mm do not move with the airflow, but move irregularly due to the impact of air molecules, which is called “Brownian diffusion motion”. If it hits the filter fibers it is captured. The smaller the particles, the more intense the diffusion movement, the more opportunities to hit the fibers, and the better the filtration effect. Many friends have a misunderstanding, that is, the larger the volume of particles, the stronger the removal ability of HEPA. In fact, this is not the case. HEPA relies on the van der Waals force between fine particles and solids to work, so it is effective for 0.5 microns and above and 0.1 microns. The filtration efficiency of particles below microns is very good. Since particles of 0.1 microns undergo Brownian motion, the smaller the particles, the stronger the Brownian motion and the more times they are hit, and the adsorption effect is good. Particles above 0.5 microns undergo inertial motion. In motion, the greater the mass, the greater the inertia, so the filtering effect is better. In comparison, particles with a diameter of 0.1-0.3 microns have become difficult to remove by HEPA. Note: The attraction between molecules, molecular groups and the surface of molecular groups includes orientation force, induction force and dispersion force. Dust adheres to the filter media mainly by van der Waals force.
9. Service life

<font face=" The length of time before the air filter reaches the recommended final resistance value, at which point the air filter must be replaced or cleaned.

If you put aside the problem of the filter itself, it depends on the environment and pre-filter used.

The atmospheric environment of the fresh air intake is poor

Pre-filter efficiency and filter material area directly affect the service life

The quality of the air filter itself affects its service life

10. DHC

dust holding capacity, when the air filter reaches the final pressure drop The amount of dust contained.
11. Filter function

Remove solids from fluids (fluids: air, water, etc.)
12. Dust-free workshop

refers to removing particles, harmful gases, bacteria, etc. in the air within a certain space Specially designed rooms are designed to eliminate pollutants and control indoor temperature, cleanliness, indoor pressure, air flow speed and air flow distribution, noise, vibration, lighting, and static electricity within a certain range.
13. Air filter sealing method

Contact packing seal, (the sealing fillers include solid gaskets such as neoprene rubber, closed-cell sponge rubber, etc.) and liquid sealants (such as: Silicone rubber, neoprene, natural rubber). The solid sealing gasket generally adopts the sealing method of mechanical compression of the bolt nut. The compression amount of rubber sheets is generally 30%-50%. Liquid sealant seals by filling and adhering. This sealing method is the most commonly used sealing method in general clean rooms.

Liquid tank knife edge seal, injecting a certain height of non-Newtonian sealing liquid into the groove frame (such as: chloroisobutylene, etc.), the knife edge of the filter is inserted into the sealing liquid, so that the air passages on both sides are blocked to achieve sealing purposes. This sealing method has strong reliability and is easy to disassemble and assemble the filter. It is usually used in clean room sealing of class 100, class 10 and higher.

14. Relative humidity

Air can run humidity level. Expressed as a percentage of the maximum amount of water vapor that can be present when the steam is saturated.

ight:bold;font-size:19px”>12. Dust-free workshop

Refers to the elimination of pollutants such as particulates, harmful gases, bacteria, etc. in the air within a certain space and the indoor temperature, cleanliness, indoor pressure, air flow velocity and air flow distribution, noise vibration and Lighting and static electricity are controlled within a certain range, and a specially designed room is given.
13. Air filter sealing method

Contact packing seal, (the sealing filler has a solid gasket such as : chloroprene rubber, closed-cell sponge rubber, etc.) and liquid sealants (such as: silicone rubber, chloroprene rubber, natural rubber). Solid sealing pads generally use bolt nut machinery Compression sealing method. The compression amount of rubber plate is generally 30%-50%. Liquid sealant seals by filling and adhering. This sealing method is the most commonly used sealing method in general clean rooms.

Liquid tank knife edge seal, injecting a certain height of non-Newtonian sealing liquid into the groove frame (such as: chloroisobutylene, etc.), the knife edge of the filter is inserted into the sealing liquid, so that the air passages on both sides are blocked to achieve sealing purposes. This sealing method has strong reliability and is easy to disassemble and assemble the filter. It is usually used in clean room sealing of class 100, class 10 and higher.

14. Relative humidity

Air can run humidity level. Expressed as a percentage of the maximum amount of water vapor that can be present when the steam is saturated.