Long-term low-temperature operation of variable-frequency screw compressors leads to accumulated moisture inside the oil separator tank. Under such conditions, the filter paper requires relatively strong water resistance. When a variable-frequency screw air compressor runs under low frequency, the pressure of the oil circuit system will be low. Therefore, the oil filter must feature low resistance and excellent air permeability.

The main function of an oil filter is to remove impurities from lubricating oil. Most customers tend to believe that higher filtration precision delivers better filtering performance, yet they worry that excessively high precision will cause frequent clogging. In fact, this viewpoint is incorrect.

Experiments indicate that although filtration precision is somewhat related to filtering performance, the decisive factor is not precision itself, but the adsorption capacity of the oil filter paper. The greater the dust holding capacity, the stronger the adsorption capacity and the better the filtering effect. Fiber filter paper achieves outstanding filtration performance thanks to its large dust holding capacity, powerful adsorption capacity and strong anti-carbonization performance.

Nevertheless, fiber filter paper comes at a relatively high price. Moreover, most filter paper manufacturers do not support retail sales; customized orders require mass production. Custom fiber filter paper is difficult to obtain for customers with low oil consumption, which explains why only a small number of users select fiber filter paper.