METHOD AND APPARATUS FOR SPRAYING A LIQUID COATING CONTAINING SUPERCRITICAL FLUID OR LIQUIFIED GAS

摘要

METHOD AND APPARATUS FOR SPRAYING A LIQUID COATING CONTAINING SUPERCRITICAL FLUID OR LIQUIFIED GAS 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 to a nozzle at the tip of the gun and then to an outlet 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 and the nozzle to avoid the formation of an area of ambient or reduced pressure so that the supercritical fluid or liquid gas is substantially maintained in solution in the liquid coating until it is discharged from the gun. A pressure regulator is provided to maintain a substantially constant pressure drop across the inlet and outlet of the gun to induce flow of liquid coating material through the gun, and to permit several guns to be connected in series without creating a substantial pressure drop therebetween.