Drain valves serve to remove compressed air condensate from filters and filter pressure regulators on the equipment of all ewo series in all sizes. Manual drain valves are fitted on our filters as standard equipment. Other types of drain valves (semi-automatic drain valves, fully automatic externally fitted drain valves A or B, and fully automatic internally fitted drain valves) can be mounted as an option. Manual Drain Valves Manually operated drain valves are integrated as standard equipment in all filter bowls or filter-pressure-regulator bowls. On plastic bowls or metal bowls with sight glass a plastic drain screw is used. A metal drain screw is used on metal bowls without sight glass, but if desired it can be optionally screwed into any other bowl with female port thread in place of the plastic drain screw. Semi-Automatic Drain Valve Semi-automatic drain valves are open when there is no pressure (up to approx. 0,5 bar). At higher pressures they are opened manually. They are thus used in all situations where at least during the night the compressed air system is shut off and relieved. With the appropriate insert they can be installed in all bowls of plastic or metal having a sight glass. For installation in metal bowls without sight glass or G1/8 female thread no insert is necessary. The manual operation is carried out by pushing the brass plate up over the plug of the drain hose for condensation. External-Automatic Drain Valve Fully automatic drain valves can be fitted on all filters or filter pressure regulators in the ewo-programme instead of manually operated or semi-automatic ones. On bowls with G1/8 female thread the installation is possible at any time. The working pressure range runs from about 4 bar to 16 bar. At pressures below 4 bar the valve is closed and the automatic function turned off. Between 4 and 16 bar when a certain condensation level is reached, a float activates a pneumatic servo valve and the drain valve is opened. After brief draining the valve closes again. Emergency manual operation is carried out by pressing in a horizontally protruding pin. Internal-Automatic Drain Valves Fully automatic built-in drain valves (Ø24mm) are suitable for installation in all plastic bowls with Ø14mm hole and an WZ19 adaptor. The operating pressure range of the valves runs from approx. 1,5 to 12 bar. At pressures below 1,5 bar the valve is open. Between 1,5 and 12 bar when a certain condensation level is reached, a float activates a pneumatic servo valve and the drain valve is opened. Emergency manual operation is effected by pushing up the red ring.