Abstract: A sluice type apparatus for discharging batches of material from a pressurized enclosure has a container with an upper inlet and a lower outlet each closable by a slide gate. Preferably, each slide gate has two slide gate members driven by respective piston cylinder devices so that one gate is closed while the other gate is open and vice versa. At least the slide gate members for opening and closing the inlet are withdrawn from their inlet closing position into a respective outwardly closed or sealed chamber for making it easier to keep the container pressurized. The seals between the chamber entrance slots and the respective slide gate member are not required to be precision seals because any material that may pass into these outwardly closed or sealed chambers is easily removed again.