Abstract

A device for feeding metal powders suspended in a conveying gas uniformly and controllably to a point of utilization such as a flame spray gun comprising an enclosed hopper which contains the powder in particulate loose and by and large unfluidized form and is supplied in its upper portion with a controlled amount of fluidizing gas. A conduit with a downwardly opening powder intake conduit passes through the lower portion of the hopper and is supplied with a conveying gas at a pre-determined rate. The fluidizing gas passes through the mass of solids and is diffused thereby. It converges towards the orifice, suspends the powder in the vicinity of the orifice, upturning into the orifice to do so, and propels the fluidized powder therethrough into the conveying gas. The amount of fluidizing gas flow determines the amount of solids placed in the conveying gas. The fluidizing gas flow is controlled inversely responsive to the pressure at a point in the conveying gas line.Preferably, a fluidic amplifier or controller is integrated into the system for the purpose of regulating the flow of the fluidizing gas. In this embodiment, the control gas for the amplifier is tapped from the conveying gas line upstream of the solids inlet orifice. The flow of control gas is thereby automatically regulated by the pressure in the control gas line at the point of tapping, which pressure is responsive to the mass flow rate in the conveying gas line downstream of the solids inlet orifice.