Molecular sieve 4A is suitable for the drying of gases(e.g: natural gas, petrol gas) and liquids, with an aperture of about 4 angstroms The working principle of molecular sieves is mainly related to the pore size of molecular sieves, which are 0.3nm/0.4nm/0.5nm respectively. They can adsorb gas molecules whose molecular diameter is smaller than the pore size. The larger the size of the pore size, the greater the adsorption capacity. The pore size is different, and the things that are filtered and separated are also different. In simple terms, 3a molecular sieve can only adsorb molecules below 0.3nm, 4a molecular sieve, the adsorbed molecules must also be less than 0.4nm, and 5a molecular sieve is the same. When used as a desiccant, a molecular sieve can absorb up to 22% of its own weight in moisture.