1. Water detection, this is also the most critical and simplest method of identification. For the inexperienced, water is the best way to detect the quality of the air filter. Place the air filter flat on the ground or on the table and sprinkle some water on the filter paper. 
    1） If the filter paper seeps into the water within 5 minutes, it is an air filter made of cotton pulp paper and absolutely cannot be used. This kind of product is used by a few cheap people in the air compressor industry;
    2）If the filter paper seeps into water within 2-5 hours, it is made of low-grade wood pulp paper and can be used, but it will affect the air compressor efficiency (more power consumption, less air). As the price of the air filter made of this kind of filter paper is relatively low, it can also be used on the air compressor, but it consumes more power and less air, so now the air filter of this kind of filter paper in the air compressor industry is the mainstream;
    3） If the filter paper only seeps in within 12-15 hours, it is a decent filter paper (mid-range filter paper). Generally, domestically produced machine factories with better quality use the air filter of this type of filter paper as the original consumables;
    4） If the filter paper does not seep in for 24 hours, it is definitely a premium product (high-end filter paper). Usually, high-end machine manufacturers choose this type of filter paper as the original consumables;

2. If the filter paper does not seep in for 24 hours, it is definitely a premium product (high-end filter paper). Usually, high-end machine manufacturers choose this type of filter paper as the original consumables;

3. Look at the depth of the filter paper and the number of folds. If the filter paper is deep and the number of folds of the filter paper is large, it means that the air filter has a large filtering area, and the air filter has a large filtering area, and the air permeability will be better.