Abstract: Dust emission is controlled by a preferably short fill at the expulsion end of each chamber, and selective venting of residual pressure through the air-inlet end. This selective venting is accomplished through use of a novel seal or "pad" that has an extension for tightly covering and sealing the material-exhaust end of each chamber while the chamber is in a dust-control plenum. The pad extension is notched so that it leaves the air-inlet end uncovered, permitting pressure venting through the notch and the air-inlet end. To provide truly effective sealing of the pad extension against the wear plate above the chamber that is in the plenum, the extension is reinforced by a strong metal plate which is embedded in the pad. Careful contouring of the main material-conveying ports in the pad optimizes the performance. A new all-pneumatic pad-clamping pressure-control system has been found to provide excellent control of pressure and uniformity of wear, with a minimum of working parts and adjustments.

Abstract: A rotary feed structure for a gunite-conveying machine includes a polymeric body to resist sticking of gunite even if the latter includes silica fume, and even if it has set. The body has chambers in a circle. Preferably the body is urethane, self-bonded to a Ni-hard wear plate to eliminate radial leakage, and the mounting, (typically holes for studs), at least in part, is integral with the plate. A metal axial spacer is preferably next to the plate, but only within the innermost radius of chambers and with a sizable wall thickness. The body is preferably a feed-bowl type, with chambers formed as generally U-shaped pockets. A gunite machine using the polymeric feed structure also has a hopper, delivery tube, support and rotation of the feed structure, compressed-air for expelling the particulate material from the chambers into the tube, and provision for transporting the hopper, tube, body, and other apparatus. Chambers are selectively sealed to the expelling device and delivery tube.

Abstract: One aspect of this gunite or refractories gun is a seal-clamping system that applies an essentially constant force despite variables such as wear of the seal or seals. Another aspect is a combination of hydraulic control and mechanical cams to clamp the seal(s). Ideally both aspects are used. Preferably the system also balances seal-clamping forces at different points. Chambers in a rotary feed structure carry material from a hopper at a receiving port to a delivery tube at a discharge port. Gas (usually air) flows from a pneumatic supply orifice to blow material from the feed structure into the distance port. One or more seals are used to seal the path that is formed by the pneumatic supply orifice, at least one chamber (when generally in position for discharge), the discharge port, and the delivery tube. A set of cams or other mechanical apparatus applies force to press the seal(s) against the feed structure.