Abstract: Thermoplastic powder entrained in a stream of carrier gas is conveyed through a carrier gas line extending between a flame spray applicator and a remote supply hopper. A bypass line is included to divert the carrier gas before it reaches the hopper and introduce it into the carrier gas line immediately downstream of the hopper, whereby powder supply from the hopper can be terminated while the carrier gas continues to purge the carrier gas line downstream of the hopper to remove contained powder. The flame applicator delivers fuel gas, combustion air and a carrier gas-powder mixture in separate streams to maximize the quality of the flame and the surface coating. The carrier gas-powder mixture is delivered as a central stream, the combustion air as a generally concentric annular stream around the central stream and the fuel gas as an outermost generally concentric annular stream. The body member is formed with a first central bore for delivering the carrier gas-powder mixture.