Similarities and differences between compressed air and ventilation air filters

Since ancient times, in order to survive and multiply better, human beings have invented various "filters" to filter impurities and harmful substances in food and water for human consumption, production and living needs. However, since the beginning of the human industrialization revolution, human beings have started the process of industrialization, which has increased the amount and types of pollutants that human beings emit into the nature, causing the air in the natural environment to be polluted more and more deeply, so that it threatens the survival and reproduction of human beings, such as: more and more serious haze, greenhouse gas emissions with higher and higher concentrations. Although the human body is born with a "body filter", its filtering capacity is limited within a certain range. At the same time, in some occasions, such as surgery, sterility must be required. Therefore, a filter independent of the outside of the human body must be invented and designed to filter the air, so there is an air filter or equipment, which we call ventilation air filter for short.

In view of the fact that the air in nature is free and unlimited, human invented the air compressor, which converts the natural air into air with certain pressure and turns it into a kind of kinetic energy, which is used in human production and life. At the same time, the compressed air filter is also derived. So, the ventilation air filter and the compressed air filter are both members of the "filter" family. What are their characteristics?

1. Whether it is a ventilation air filter or a compressed air filter, physical barrier technology is usually used to separate other components in the medium, such as solid particles, water droplets, oil mist and other aerosol impurities, so as to obtain clean air.

2. Their working environments, filtering objects and working pressure ranges are different. The ventilation air filter is mainly used to purify the air in the natural environment. It is applied in the fields of air conditioning, clean workshops, workshops, etc. Its working pressure is near the atmospheric pressure; Compressed air filter is mainly used for compressed air, that is, pipeline air. Its working pressure ranges from several atmospheres to hundreds of atmospheres.

3. Common categories and characteristics of ventilation air filter:

1) Coarse filter: mainly used for catching 5 μ Suspended particles above m and 10 μ Settling particles above m and various foreign matters shall be prevented from entering the clean space. It is mainly used for the first filter of the air supply system, with an efficiency of 80% ≥ η ≥ 20%, the efficiency is 5 μ M shall prevail.

2) Medium efficiency filter: mainly used for catching 1 μ m～10 μ M suspended particles. The filter is mainly used for air conditioning system, with efficiency of 70% ≥ η ≥ 20%, with the efficiency of 1 μ M shall prevail.

3) High and medium efficiency filter: mainly used for catching 1 μ m～5 μ M suspended particles. It is mainly used at the end of the system with high degree of purification, and the efficiency is 99% ≥ η ≥ 70%, with the efficiency of 1 μ M shall prevail.

4) Sub high efficiency filter: mainly used for catching 1 μ Submicron particles below m. Efficiency is 99.999% ≥ η ≥ 99.9%, with filtration efficiency of 0.5 μ M shall prevail.

5) High efficiency filter: mainly used for catching ≤ 0.5 μ M or ≤ 0.1 μ Submicron particles below m. Efficiency at η ≥ 99.999%, the efficiency is 0.3 μ M or 0.1 μ M shall prevail.

Among them, due to the high difficulty in filtering micro particles, high efficiency filters are generally divided into four categories: A, B, C and D to meet the requirements of different filtering accuracy and efficiency.

6) The filter materials of ventilation air filter are mostly fiber, glass fiber, melt blown fiber mesh, ePTFE film, etc. Its structural form is also mostly frame type, which is usually placed outdoors, and should also consider beautiful, reliable and pleasing to the eye.

4、 Features of compressed air filter:

1) The main task of compressed air filter is to filter out all pollution impurities except water vapor.

2) Because the physical properties of compressed air have obvious changes, such as temperature, pressure, density and specific enthalpy, which with the increase of pressure, and the specific volume decreases inversely with the pressure. At the same time, the concentration of impurities in the unit volume of compressed air has greatly increased, such as oil mist, oil vapor, and saturated liquid water. Therefore, the compressed air filter shall withstand the pressure of high temperature, high pressure, high humidity and load. The temperature may be higher than 80 ℃, and the pressure may reach dozens of atmospheres.

3) Based on the principle that the inlet and outlet gas velocities change due to the difference of the inner and outer surface areas of the filter element, the cylinder is usually used as the compressed air filter

On the one hand, multiple filtering mechanisms can be applied to improve filtering efficiency; The other is from the perspective of pressure bearing.

4) Due to the different purposes of using compressed air in various industries and processes, the requirements for filtering accuracy and impurity content of compressed air are different

of Therefore, the filter materials used for compressing the filter element are also rich, such as fiber, ceramics, filter paper, non-woven fabric, sintered metal, etc.

5) When the compressed air filter works, the intercepted water (except for water vapor) and mixed water of impurities will act together with gravity

It flows down and accumulates in the filter cartridge, but cannot be directly discharged immediately. For this reason, it is usually equipped with manual or automatic drainage

Device and window for monitoring liquid level.

6) As the compressed air is sealed in the filter cartridge under pressure, it is usually necessary to provide

The differential pressure indicator of inlet and outlet air pressure drop shall be prepared to indicate the degree of clogging of the filter element and the service life of the filter element

Life.

In a word, compressed air filters and ordinary air filters have their own application fields and needs. Their structural design

The design of filtration mechanism is also different. As an employee specializing in the R&D, production and manufacturing of compressed air system purification products and equipment

We must master the characteristics of compressed air, and then innovate and develop the compressed air filter to make it more efficient and have a longer service life

Long and more economical.

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