The air-treatment equipment of the screw air compressor is mainly composed of an air storage tank, a dryer and a filter. In the filter part, it is divided into a pre-filter and a post-filter, which are generally separated by a dryer. The compressed air is discharged from the unit to the air storage tank, to the pre-filter, to the dryer, and then to the filter. The post-filter is used to complete the purification treatment such as filtration and drying.

Today, the editor will introduce to you the difference between the pre-filter and the post-filter of the air compressor?


The pre-filter can perform preliminary filtration and purification of compressed air, and can remove a large amount of water, oil and larger particles to be filtered out, playing the role of maintenance. Therefore, the pre-filtration of the air compressor is the pre-treatment of the compressed air, stop the preliminary filtration, and filter out larger particles.

Pre-filter: Remove some liquid water, lubricating oil and particles with a diameter larger than 1μm. Whether it is an adsorption dryer or a refrigeration dryer, a pre-filter is required. Otherwise, once the evaporator is blocked by rust and other particles on the pipe, the working efficiency of the cold dryer will be greatly reduced and the evaporator will be damaged.


The post-filter is relatively precise. Compressed air enters the post-processing stage, and basically no liquid is discharged. Assuming that the compressed air containing a large amount of impurities is directly processed through the post-filter, there is no need for maintenance of the pre-filter, which may cause gas-water separation. The phenomenon of blockage and damage of the drain valve and drain valve.

Post-filter: Remove the oil mist concentration in the compressed air to a higher standard, and remove the oil mist concentration greater than 0.01μm particles and oil content greater than 0.001ppm. Under normal circumstances, there is almost no liquid water discharged from the rear filter. If there is, it means that the gas-water separator or drain valve inside the cold dryer is faulty.

In summary, we can see that the main function of the pre-filter is to perform preliminary filtration and purification treatment on the compressed air, which can filter out a large amount of water, oil and larger particles, and at the same time protect the unit. Therefore, the pre-filter of the air compressor is the pretreatment of the compressed air, and performs preliminary filtration to filter out relatively large particles. The post-filter is relatively precise. When the compressed air enters the post-processing stage, basically no liquid is discharged. If the compressed air containing a large amount of impurities is not protected by the pre-filter, it will be directly processed by the post-filter. It may cause blockage or even damage to the gas-water separator and drain valve.


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