1/2" particulate filter water trap seperator moisture compressed air compressor thb this is a low cost simple option to remove moisture from your air lines on single stage air compressors. this unit has a semi automatic drain that acts like an overnight drain. when pressure is applied to the bowl, the drain will hold the moisture contents unless you manually discharge it. when no pressure is applied to the bowl, the drain automatically opens to release the moisture. if you remove the bowl from the unit and do a water test to see if holds moisture, the bowl will leak. that is what its designed to do. when pressure is applied, the bowl will hold moisture contents and pressure. the best way to separate air and moisture from your compressed air lines, starts with your compressed air lines themselves. always force air to climb vertically while pooling liquid moisture is forced downwards by gravity. this allows only moisture vapor to reach your filters and will prolong the life of your filters and air tools. you can always search online " proper compressed air line installations" to get some ideas.