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Air compressors are widely used in various industries, but it’s not only the compressors that need to be chosen – attention should also be paid to post-treatment purification equipment. What factors should be considered when selecting compression air purification equipment to ensure a scientific approach? 1) Selection based on the precision required for particle filtration: 1) When compressed air comes into direct contact with the product or there is a possibility of such contact, and any particulate impurities could affect the quality of the production process as well as the final product, it is necessary to restrict impurities such as solids, microorganisms, water, and oil in the compressed air in accordance with the specifications outlined in the technical documents, and select appropriate purification equipment accordingly. Such as healthcare, medical devices, food, high-tech electronics, chips, high-precision recording discs, etc. 2) For general-purpose processes and pneumatic systems, the degree of purification of compressed air from solid and liquid contaminants can be determined based on the following factors: 1) the structure and materials of the pneumatic equipment and control systems; 2) the size and precision of the air flow channels and holes in the pneumatic components and instruments; 3) the requirements regarding system reliability and lifespan; 4) the operating conditions and the nature of the impact of contaminants. It must be noted that the higher the hardness of the impurity particles, the greater the wear on the various components in the pneumatic system, and eventually these components will be damaged due to wear and frictional heating. The larger the geometric size of the impurities, the easier it is for them to block the ventilation pores in the components. The table below shows the grades for solid particles as specified in GB/T 13227.1-2010 \"Compressed air – Part 1: Pollution control levels\". II. Selection based on the required dew point: 1) When compressed air is in direct contact with the product or there is a possibility of such contact, and the moisture content in the compressed air can affect the process quality and final quality of the product, it is necessary to limit the moisture content in the compressed air in accordance with the specifications outlined in the technical documents, and select appropriate drying equipment. For example: healthcare, medical devices, food, high-tech electronics, chips, high-precision recording discs, etc. In other general-purpose processes and pneumatic systems, the dew point of compressed air must be determined based on the sensitivity of each specific component to moisture content. There are also some pneumatic devices whose friction surfaces do not come into direct contact with compressed air, for which no requirements are set regarding the liquid water content in the compressed air. 2) The general approach is to ensure that the dew point temperature of compressed air under operating pressure (pressure dew point) is at least 6–10°C lower than the lowest possible ambient temperature. However, the following points should be kept in mind: ① The dew point must be selected based on actual requirements; a lower dew point is not necessarily better. According to the law of conservation of energy, a lower dew point requires additional energy to be supplied; in other words, the lower the dew point, the more energy is needed. In a market characterized by energy shortages and cost competition, energy saved translates into pure profit and cost competitiveness. ②The exhaust dew point is the ultimate indicator of dryer efficiency; it is determined by factors such as inlet temperature and inlet pressure, and is closely related to the energy consumption during the drying process. Lowering the intake air temperature and appropriately increasing the intake air pressure are beneficial to the performance of the dryer; conversely, they will have a negative impact on the exhaust dew point and energy consumption of the dryer. For example, at an intake air temperature of 38°C, the saturated water content in the compressed air is 46.1 g/m3; when the intake air temperature rises to 45°C, this value increases to 65.3 g/m3. The energy consumption also increases accordingly. For instance, if the intake air temperature to the refrigerated dryer exceeds 38°C, it is recommended to use a pre-cooler to lower the temperature before it enters the refrigerated dryer. The same is true for adsorption dryers; the inlet air temperature should be reduced as much as possible. ③During the regeneration of adsorption drying, some compressed air is consumed; therefore, zero air consumption is not achievable in 100% of cases. As such, this loss must be taken into account when selecting the flow rate of the air compressor. ④Also, pay attention to the significant impact of changes in thermodynamic parameters on the compressed air drying process. For example, in the working chamber, due to the rapid movement of the piston, when air supply is interrupted or throttled, and in pneumatic actuating elements (cylinders and pneumatic motors), expansion occurs as air is discharged from the element’s exhaust chamber; this can lead to the condensation of water vapor and oil vapor. GB/T 13227.1-2010 \"Compressed air – Part 1: Pollution level classification\" specifies the dew point levels. III. Selection based on oil content: In pneumatic systems that do not require the addition of lubricants during operation, any oil present in the compressed air should be considered a contaminant. In pneumatic systems that do require the addition of lubricants, any anti-rust oils or compressor oils present in the compressed air are also regarded as contaminants. In processes that are highly sensitive to oil contaminants, such as high-end painting applications, the food and pharmaceutical industries, and oxygen production equipment, it is required that the compressed air be 100% oil-free. In short, all oil-based impurities (including oil vapor) present in the compressed air discharged from air compressors are harmful to pneumatic systems. They not only contaminate products and affect the proper operation of these systems, but they can also lead to catastrophic consequences due to the accumulation of oil vapor. GB/T 13227.1-2010 \"Compressed air – Part 1: Pollution control levels\" specifies the levels and values related to oil content. The oil grade is shown in the table below. The measurement of suspended oil and liquid oil is carried out in accordance with ISO 8573-2, while the measurement of oil vapor is done according to ISO 8573-5; their sum represents the total oil content. The control elements and actuating elements used in many pneumatic systems generally require lubrication; otherwise, friction increases, accelerating the wear of the sealing elements and thus affecting their service life. Special-shaped components (such as oil misters) can be installed in the air ducts to turn ordinary liquid oil droplets—these being specialized, clean, and harmless lubricants, as opposed to the compressor oil found in compressed air—into fine oil mist that is mixed into the air and delivered to the areas where it is needed. To remove various contaminants such as water, oil, and dust present in compressed air, thereby improving the reliability and service life of pneumatic equipment and reducing the impact of these contaminants on the processes that rely on compressed air, it is necessary to use compressed air purification equipment. However, the specific number of such units required depends on the actual air usage standards of different industries. Of course, in many practical applications, this fine full-mouth P-spoon effectively removes impurities, without affecting the normal performance of pneumatic equipment and systems, nor does it impact product quality. Therefore, if a blind pursuit of complete purification is undertaken, huge costs will be incurred, and its economic viability may not be reasonable.