A waterjet cutting method is provided which includes directing a waterjet onto a surface of a workpiece that is exposed to the surrounding atmosphere, the interaction of the waterjet with the exposed surface defining a cutting location, and simultaneously directing a gas stream onto the exposed surface of the workpiece at or adjacent the cutting location to maintain a cutting environment at the cutting location that is, apart from the waterjet, substantially devoid of fluid or particulate matter. The method may further include moving a source of the waterjet relative to the workpiece to cut the workpiece along a desired path while continuously directing the gas stream onto the exposed surface of the workpiece at or adjacent the cutting location.

A fragmenter provides fragmentation of frangible blast media entrained in a subsonic flow. The flow is converged prior to reaching a fragmenting element, and the convergence may be followed by a constant cross-section area section. Immediately upstream and downstream of the fragmenting element may be an expansion area to reduce the potential of water ice buildup.

The present invention is a nozzle assembly having a nozzle main body including an ejection material suction port and an ejection port which ejects the ejection material with the compressed air, and an air nozzle which jets the compressed air into the nozzle main body. The nozzle main body includes a mixing chamber which mixes the ejection material with the compressed air, a first pathway directed from the ejection material suction port toward the mixing chamber, and a second pathway directed from the mixing chamber toward the ejection port. The air nozzle includes a compressed air jet portion and a third pathway directed to the compressed air jet portion, and the third pathway is inserted into the nozzle main body. The compressed air jet portion of the air nozzle is provided with a flow contracting portion having an opening.

A method for cleaning tooth surfaces with a powder and a powder mixture, preferably by powder blasting with a powder-jet device, said device mixing the powder or the powder mixture with air to form a powder/air mixture, wherein said powder and/or powder mixture is an alditol or contains such alditol. Preferably, mannitol and/or erythritol are used, because of their anti-cariogenic effect. Xylitol is also suitable for cleaning tooth surfaces, especially of less strongly mineralized tooth surfaces like dentine.

A waterjet cutting head assembly is provided which includes an orifice unit to generate a high-pressure waterjet, a nozzle body and a nozzle component coupled to the nozzle body with the orifice unit positioned therebetween. The nozzle component may include a waterjet passage, at least one jet alteration passage and at least one environment control passage. The jet alteration passage may intersect with the waterjet passage to enable selective alteration of the waterjet during operation via the introduction of a secondary fluid or application of a vacuum. The environment control passage may include one or more downstream portions aligned relative to the fluid jet passage so that gas passed through the environment control passage during operation is directed to impinge on an exposed surface of a workpiece at or adjacent to a location where the waterjet is cutting the workpiece. Other high-pressure waterjet cutting systems, components and related methods are also provided.

The mixing device for mixing a powder with a pressurized gas, comprising a mixing chamber (20) with an inlet area (22), which has at least one inlet opening (24), by way of which powder and/or pressurized gas and/or a mixture thereof may be introduced into the mixing chamber (20), and at least one outlet area (26), which is designed for withdrawing from the mixing chamber (20) a main flow (HR) of a gas or powder or a powder and gas mixture directed along the mixing chamber (20) which essentially extends from the inlet area (22) to the outlet area (26), characterized in that a regulating device (10) is arranged along and/or in continuation of the main flow (HR), regulating the main flow (HR) of the gas or powder or powder and gas mixture.

An abrasive jet cutting system may include a differential pressure measurement apparatus configured to measure a differential pressure between points in an abrasive supply system. The differential pressure may be used to determine one or more conditions of the jet and the abrasive delivery. The measured differential pressure may be used in a feedback control system, feed forward control system, and/or an alarm or safety system.

An abrasive jet cutting system may include a differential pressure measurement apparatus configured to measure a differential pressure between points in an abrasive supply system. The differential pressure may be used to determine one or more conditions of the jet and the abrasive delivery. The measured differential pressure may be used in a feedback control system, feed forward control system, and/or an alarm or safety system.

A grit blasting arrangement for cleaning chemical reactor tubes includes means for ensuring the grit blast nozzle is coaxial with the longitudinal axis of the tube to be cleaned. The grit blasting device for cleaning tubes spaced apart by upper and lower tubesheets. The grit blasting device includes a grit blast nozzle mounted on a positioning frame and projecting outwardly with an outlet directed into a tube opening during a cleaning operation. The device includes a plurality of stop pins mounted on the positioning frame designed to abut a tubesheet and to define an imaginary plane coplanar with the tubesheet. The plurality of stop pins when abutting the tubesheet prevent the outlet of the nozzle from extending into the tube causing a venturi effect.

Nozzle system for a powder blasting device including a first nozzle element for transporting a powder-gas mixture stream along a transporting direction and a second nozzle element, where the second nozzle element surrounds the first nozzle element such that at least one channel is formed between the first nozzle element and the second nozzle element, where the channel is provided for transporting a liquid stream, where the first nozzle element and the second nozzle element are arranged such that in operation the powder-gas-mixture stream ejected by the first nozzle element is encased by the liquid stream ejected by the channel for forming an output stream of the nozzle system, where the first nozzle element has an acceleration part having a first cross section and a spreading part having a second cross section, where the spreading part is arranged downstream of the acceleration part.