Abstract: An abrasive feed system is shown in FIG. 3 in which pressurized air from air compressor (10A) is cooled and dried by heat exchanger (123A), water separator (125A) and chemical air dryer (127A) for delivery to a differential pressure regulator (104A) and an abrasive container (100A) for sodium bicarbonate or other hydroscopic or water soluble or moisture sensitive particles. Differential pressure regulator (104A) senses the fluid pressure in transport line (117A) though a sensing line (130A) and automatically maintains the fluid pressure in air supply line (102A) to the abrasive container (100A) at a predetermined set pressure differential between line (102A) and (117A) so that the pressure in line (102A) is maintained at a predetermined pressure level above the pressure in transport line (117A).

Abstract: In accordance with illustrative embodiments of the present invention, a hopper containing a sodium bicarbonate abrasive is pressurized with a dry gas such as nitrogen. The abrasive is fed into a transport line through which compressed air flows toward a nozzle, and pressures in the hopper and transport line are regulated so that the hopper pressure is greater than the transport line pressure by an amount that keeps the abrasive in the hopper very dry so that the same differential pressure causes a precisely metered amount of abrasive flow.

Abstract: In accordance with illustrative embodiments of the present invention, a hopper containing a sodium bicarbonate abrasive is pressurized with a dry gas such as nitrogen. The abrasive is fed into a transport line through which compressed air flows toward a nozzle, and pressures in the hopper and transport line are regulated so that the hopper pressure is greater than the transport line pressure by an amount that keeps the abrasive in the hopper very dry so that the same differential pressure causes a precisely metered amount of abrasive flow.Another aspect of the invention relates to a method of cleaning by applying a stream of dry water soluble abrasive particles, such as sodium bicarbonate particles, entrained in air, as the abrasive agent to a cavity of a blast nozzle to which water under pressure is also applied. Such method includes the step of directing the output of the nozzle toward a surface to be cleaned.

Abstract: A method and apparatus is disclosed for using a nozzle to propel abrasive particles with high pressure water. The nozzle has a straight line path for a constant flow rate of air and abrasive particles to a propulsion chamber. A water path through the nozzle also opens into the propulsion chamber, with both the abrasive path and water path intersecting in the chamber. An outlet bore is provided through the nozzle and communicates with the chamber. A high pressure water supply is used and an air and abrasive supply means independent of the water supply is used to deliver a constant flow of air and abrasive particles. The water inlet path accelerates the water in a propelling jet toward and in alignment with the outlet bore so as to impact the abrasive particles and create a high energy abrasive blast through the outlet bore.

Abstract: In accordance with illustrative embodiments of the present invention, a hopper containing a sodium bicarbonate abrasive is pressurized with a dry gas such as nitrogen. The abrasive is fed into a transport line through which compressed air flows toward a nozzle, and pressures in the hopper and transport line are regulated so that the hopper pressure is greater than the transport line pressure by an amount that keeps the abrasive in the hopper very dry so that the same differential pressure causes a precisely metered amount of abrasive flow.

Abstract: A liquid-propelled abrasive cleaning apparatus comprising a nozzle for applying a high pressure stream of water and propelled sand particles to a surface to be cleaned; a pump for furnishing water under high pressure to the nozzle, the pump being of a kind which may be driven by a pressurized fluid medium and having a discharge outlet; a first conduit for connecting the outlet to the nozzle; a second conduit for delivering the medium to the pump; a normally closed valve in the first conduit; a pneumatic actuator for opening the valve; and a control device disposed in proximity with the nozzle for enabling pressure to be applied to the actuator to open the valve only when the nozzle is in use.

Abstract: A propulsion apparatus adapted for use in a liquid propelled abrasive cleaning system is disclosed in which high pressure water is injected coaxially in a bore of a housing to which a flow of air and abrasive is introduced. The high pressure water is introduced into the bore via a water injection member fixed in the bore. The water injection member has a cross-sectional area which is small compared to that of the bore. A first embodiment of the invention includes a wing shaped water injection member which extends diagonally across the bore of the housing. A second embodiment of the invention includes a sloping leading edge with low axle oblique surfaces serving to deflect abrasive particles around the member and back into a high velocity air/abrasive longitudinal flow. The leading edge of the water injection member is small compared to the widest part of the member in the bore thereby creating an air-foil effect for the air/abrasive mixture flow as it passes the injection member in the bore.

Abstract: In accordance with an illustrative embodiment of the present invention disclosed herein, a liquid propelled blast nozzle apparatus includes a body having first and second bores which receive, respectively, a pressurized flow of sand particles and a high pressure and high velocity flow of propulsion fluid, a nozzle assembly on the body having a third bore for directing a blast of liquid propelled sand particles onto a surface to be cleaned, the respective bores defining axes which intersect one another within the bore of the nozzle assembly, the axis of the first bore intersecting the axis of the third bore at an angle of about 31/2.degree., and the axis of the first bore intersecting the axis of the second bore at an angle of about 71/2.degree.. The first and third bores preferably are lined with a suitable wear and erosion resistant material such as tungsten carbide.