Method & apparatus for spraying a liquid coating containing supercritical fluid or liquified gas.

摘要

A method and apparatus for spraying liquid coating material containing supercritical fluid or liquified gas as a diluent comprises a spray gun having internal passages which transmit the liquid coating material under high pressure from an inlet (64) to a nozzle (50) at the tip of the gun (14) and then to an outlet (66) so that the liquid coating material can be continuously recirculated. A relatively short flow discharge path is formed between the internal passages in the spray gun (14) and the nozzle (50) to avoid the formation of an area of ambient or reduced pressure so that the supercritical fluid of liquified gas is substantially maintained in solution in the liquified coating until it is discharged from the gun (14). A pressure regulator (128) is provided to maintain a substantially constant pressure drop across the inlet (64) and outlet (66) of the gun (14) to induce flow of liquid coating material through the gun (14), and to permit several guns (14) to be connected in series without creating a substantial pressure drop therebetween.