GB384667A - Improvements in or relating to a method of and apparatus for partially vaporizing and - Google Patents

Abstract

384,667. Cleaning masonry. HOMESTEAD VALVE MANUFACTURING CO., Coraopolis, Pennsylvania, U.S.A.-(Assignees of Ofeldt, F. W. ; 532, Locust Street, McKeesport, Pennsylvania, U.S.A.) June 4, 1931, No. 16365. Convention date, June 14, 1930. [Classes 60 and 138 (i).] Sand blast.-A jet or spray of mixed liquid and vapour is produced by supplying liquid under pressure to a heating coil, heating it to a temperature below the boiling-point at such pressure but above the boiling-point at a lower pressure, and releasing the pressure at the outlet of the coil to cause a sudden change of the liquid phase in part to the vapour phase whereby a mixture of liquid and vapour is ejected. Preferably a portable apparatus is employed which is furnished with liquid and fuel pumps so proportioned as to give the required temperature and controlled by a spring to give a predetermined pressure. As shown, a casing 2 supports a coil 3 to which liquid is supplied from a reservoir 9 through a pump 7 ; also a liquid fuel burner 4 disposed above a pilot burner 6 and supplied from a reservoir 12 through a pump 10 and preheating coil 5. The pumps 7, 10 are actuated through a lever 29 adapted to be raised by a piston 26 in a cylinder 25 supplied with steam from a superheating connection 16 from the coil 3 through a valve 20 controlled by the lever 29 which is urged downwardly by a spring 39. The coil 3 is connected through a valve 15 to a nozzle 14a fitted with a throttle valve 14b. In starting the lever 29 is operated manually until sufficient steam is generated to operate the piston 26, the pumps are then operated automatically until the pressure determined by the spring 39 is attained. A modification is described in which the pump lever is actuated by a cam roller driven by an electromotor; to ensure circulation of liquid during idling periods, the outlet end of the heating coil is connected to the liquid reservoir through a relief valve and the fuel pump is supplied through a needle valve controlled by a spring piston acted upon by the liquid supply, the fuel pump piston being connected to the lever through a lost-motion connection. The heating coil is made of gradually increasing cross-sectional area and is composed of single or multiple conduits. In a typical system, the pressure corresponds to a boiling temperature of 260‹ F. and the temperature is 250-255‹ F. The invention is applicable to agricultural spraying, disinfecting, deodorizing, cleaning and the application of a weatherproof mixture to masonry. The liquid may contain a solution or suspension of cleaning or spraying material. Sand blasting may be effected by introducing a sand stream into the jet.