Abstract: A blasting apparatus, for removing coatings and contaminants on a surface by feeding a controlled volume of an abrasive medium into a compressed air stream, includes a vessel for holding the abrasive medium and an aerated-type feed valve assembly, operatively connected to the vessel, for controlling and metering an effective amount of abrasive medium into the compressed air stream, the feed valve assembly having a shaft tube having an inside diameter of at least 11/4 inches. The blasting apparatus also includes air stream hoses or manifold pipes for conveying the compressed air stream to the feed valve assembly from a source of compressed air. In addition, a blast hose is included for blasting the abrasive medium in the compressed air stream at the surface from which the coatings or contaminants are to be removed.

Abstract: A particle blast cleaning apparatus for use with sublimable blast media, a source of compressed gas, and a discharge nozzle. The apparatus includes a mixing device for mixing the sublimable media with compressed gas, which mixing device includes a lower section having an outlet port formed therein and an upper section positioned over the lower section and having two sublimable media inlet ports and a compressed gas inlet port. A transfer member is mounted between the lower section and the upper section for reciprocal movement and has at least two transfer chambers for transporting sublimable media. A control mechanism is provided for controlling the flow of compressed gas to the compressed gas inlet port such that compressed gas is only provided to the compressed gas inlet port when at least one of the transfer chambers is in fluid communication with the compressed gas inlet port.

Abstract: Improvements to blast cleaning apparatus, and particularly to a media control device which contains a fixed orifice placed between the abrasive supply pot and a media outlet to the compressed air line to meter the media flow into the air line and means to maintain a positive pressure differential between the supply pot and the air line further includes a means to equalize the pressure between the air line and a media passage immediately below the orifice. An additional improvement comprises adding a flow straightening device upstream of a bend in the air line so as to reduce back-mixing in the bend and consequently the turbulence of air downstream of the bend and across the media outlet into the air line.

Abstract: A media control valve used to meter and dispense an amount of abrasive media from a supply pot to a compressed air line for blast cleaning comprises a vertical media passage communicating with the supply pot and an air flow tube and a restricting orifice in the media passage to meter the amount of abrasive media flowing therethrough the vertical passage into the air flow tube, the media passage downstream of the orifice converging into a slot-shaped outlet into the air flow tube wherein the length of the outlet is directed along the direction of air flow through the air flow tube so as to reduce the perimeter of the outlet placed perpendicular to air flow and consequently reduce turbulence as the air passes across the outlet. The media valve is particularly useful in metering and dispensing sodium bicarbonate media from a supply pot to the air conveying line by means of differential pressure across the orifice.

Abstract: This invention relates to a carbon dioxide blast cleaning system for propelling dry-ice pellets by cryogens, namely high pressure nitrogen, helium and/or oxygen, against a surface being cleaned. Carbon dioxide pellets, in a pellet hopper, a blast unit and a blast gun are located at a blast site near the surface being cleaned. A portable cryogenic liquid nitrogen, liquid helium and/or liquid air tank with an ambient air vaporizer is also located at or near the blast site. Cryogenic liquid nitrogen, liquid helium and/or oxygen flow through the ambient air vaporizer to the liquid and is vaporized to form a high pressure gas. The high pressure, cryogenic gas is then brought into the blast unit and mixed with the pellets. The mixture of the high pressure gas and the pellets exit the gun nozzle at high velocities to blast the surface being cleaned.