Patent ID: 7478976

Claim:
Device for pneumatic conveyance of powdered material, comprising: a chamber that alternately is filled with powder and emptied, the chamber being at least partially defined by a gas-permeable material such that alternating application of positive and negative pressure to the chamber interior though the gas-permeable material conveys powder into and out of the chamber, a first valve positioned at a first end of the chamber adapted to receive powder from a supply inlet, a second valve positioned at a second end of the chamber adapted to convey powder from the chamber to a delivery outlet, and a purge arrangement for applying pressurized purge gas into the chamber interior with at least a portion of the purge gas entering the chamber interior other than by filtering though said gas-permeable material, wherein during at least a portion of the time of a purge operation, the first valve and the second valve are adapted to be open to allow purge gas to blow out of the first end and the second end of the chamber.