Filters are probably the most important items of purification equipment in a compress air system, which designed not only remove oil vapor and water, but also to remove solid particles to a acceptable levels such as small to 0.01 micron in size. Usually in Coalescing the system installation, the first filter have the purpose of pre-filtration and protecting the second high efficiency filter from bulk contamination to provide high quality compressed air. If filters worked with water adsorption or in damp condition, which will make air, cannot get through element, and airflow will force liquid through element media, increase working pressure loss and reduce filtration performance.