Abstract: There is disclosed an automatic drain valve which consists of a control block with a central bore and a coaxial inlet bore. The central bore and the inlet bore are divided from each other by a seal which is seated in the inlet bore and held in place by a threaded fitting. An outlet bore communicates with the central bore at a position displaced from the seal, and a gauge bore intersects and communicates with the central bore at a position between the inlet bore seal and the outlet bore. The seal has an opening with a beveled edge that matches the beveled leading edge on a valve stem which is slidably mounted within the central bore and operated by means of pneumatic cylinder which is in turned controlled by solenoid operated either by a conventional timer or by a humidity sensor. The seal is placed out of the direct line of flow of the water and air being drained and the valve stem is closed at high velocity in order to minimize the wear on the round seal and extend the life of the drain valve.