Patent attributes
Material is pneumatically excavated and removed by discharging air under pressure from an excavation nozzle at supersonic speeds in a forward direction for excavating the material, and simultaneously discharging air under pressure from an evacuation nozzle also at supersonic speeds in a rearward direction at an adjacent position rearward of the point of forward discharge for assisting the removal of the excavated material in a rearward direction. The evacuation nozzle is in the form of a continuous annular air stream that is maintained concentric with the excavation nozzle. The nozzles are sized to provide maximum excavation and removal efficiency in co-relation to the PSI and the CFM output capabilities of the selected air source and the nozzles are positioned sufficiently close to each other whereby dynamic flow coupling is established between the nozzles such that material digging and removal performance and efficiency are maximized.
