A pop-up valve or valve assembly operable to manage backflow, the assembly configured with a stem or stem portion. The assembly includes a valve sleeve disposed on the stem. The valve sleeve is configured to engage the stem. A stem outside diameter is smaller than an inside diameter of the valve sleeve, such that the sleeve is able to move freely on the stem and also provide a restricted passage for airflow.

A system for producing a powder-gas jet for performing a dental treatment, wherein the system is configured for being connected to a dentist chair by a connection, wherein the connection of the system to the dentist chair allows the system to be fed by a pressurized gas flow, the system comprising a compressed gas circuit configured to direct the pressurized gas flow into a powder-gas-mixing chamber to form a gas-powder mixture, the system being wherein the compressed gas circuit comprises at least a pressure regulation device having an inlet and an outlet, the regulation device being configured to provide the pressurized gas flow with a pressure at its outlet that is independent of the pressure of the gas flow at its inlet, when it is fed by the pressurized gas flow.

A wet and dry abrasive media blasting system comprises a compressed air supply providing a supply of blast air and pot air. The blast air is communicated along a blast air supply line and pot air is communicated along a pot air supply line. A blast pot is configured to receive abrasive media and pot air and release abrasive media at a discharge and into a media conduit which communicated abrasive media to a mixing device. An air pressure amplifier disposed on the pot air supply line is adapted to selectively increase the air pressure of a pot air head creating an over-pressure, such that the over-pressure which is pressure of pot air head less the pressure of the blast air is positive. The blast air and the abrasive media are mixed together in the mixing device to form a blast air media mixture which is communicated to a nozzle and discharged from the nozzle as a blast spray. The system further includes a metering valve disposed on the media conduit, downstream of the discharge, and up stream of the mixing device, the metering valve selectively controls the flow and therefore the amount of abrasive media communicated to the mixing device.

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.