Hermetic bi-flow filter driers, types DMB and DCB are for use in liquid lines on heat pumps. Hermetic bi-flow filter driers have built-in check valves which ensure that refrigerant liquid always flows through the filter driers from the outer side of the filter core towards the center. Thus all dirt particles are retained irrespective of flow direction. DMB and DCB filter driers ensure fast and effective adsorption of moisture as well as organic and inorganic acids. When building heat pump systems, the use of bi-flow filters can, depending on the type of system, save up to ten solder connections. This reduces production costs and the number of potential leakage points. Available with flare and solder (Copper and cuplated steel) connections.