Drain valve forming automatic gas seal - comprises float held above seat by fluid in vessel

摘要

The drain valve is for a vessel having a union for compressed gas used to expel the fluid contained, particularly where this is chemically aggressive. Its plug is in the form of a float (7), whose buoyancy causes it to be held in the open position above its seat (20,21) by the fluid. It drops onto the seat under gravity once the vessel is emptied, thus shutting off the gas automatically. The plug can be spherical and hollow, while there can be a cage (8,22) above the seat partly accommodating it and limiting its opening movement.