Valve operation is based on periodic pressure rise upon operation of some device in the circuit. The pipeline in which the periodic rise occurs is connected to port 1 and the tank for accumulating moisture drained from the compressed air mains is connected to port 7. The moisture fills the right end of the valve up to ball valve 6. When the pressure is raised in port 1, plunger 2, overcoming the resistance of spring 3, shifts to the right and first closes ports 4, connected to the atmosphere, and then pushes ball 6 to the right, off its seat. At this, the moisture flows into intermediate chamber 5. When the pressure in port 1 drops again, spring 3 returns the plunger into its initial position. First ball valve 6 closes, shutting off intermediate chamber 5 from the mains, and then the chamber is connected through ports 4 to the atmosphere. The accumulated moisture flows out through ports 4. The cycle is repeated each time the pressure changes in port 1. A feature of the valve is that the compressed air mains are not connected directly to the atmosphere outlet when the moisture is drained off so that no loss of compressed air occurs.
$3630$SHP,Va$