Abstract: Unusually strong and highly perforated plates are formed by pressurized filtration of a suspension of chopped ceramic fibers in an aqueous dispersion of colloidal alumina or colloidal silica through a mold having a perforated filter base and a pin support base having pins that extend through and beyond the perforations of the filter base. Pressurized filtration is preferably conducted by applying vacuum on the down stream side of the mold. When the layer of chopped fibers deposited on the perforated filter base has the desired thickness, filtration is stopped. The perforated filter base and pin support base are moved apart to retract the pins from contact with the perforated layer of chopped fibers which is transferred to a drier operating at a temperature not exceeding 650.degree. F., for conversion into a strong perforated plate.

Abstract: Unusually strong and highly perforated plates are formed by pressurized filtration of a suspension of chopped ceramic fibers in an aqueous dispersion of colloidal alumina or colloidal silica through a mold having a perforated filter base and a pin support base having pins that extend through and beyond the perforations of the filter base. Pressurized filtration is preferably conducted by applying vacuum on the downstream side of the mold. When the layer of chopped fibers deposited on the perforated filter base has the desired thickness, filtration is stopped. The perforated filter base and pin support base are moved apart to retract the pins from contact with the perforated layer of chopped fibers which is transferred to a drier for conversion into a strong perforated plate.

Abstract: A water heater of simplified construction which incorporates a unique infrared gas burner performs with notable thermal efficiency and suppression of the combustion pollutants, nitrogen oxides. The upright cylindrical water tank of the new water heater is supported by a cylindrical metal skirt having the same diameter of the tank. A circular perforated ceramic plate is fitted transversely in the skirt to provide a combustion zone above it and a plenum for fuel gas and air below it. A venturi tube extends through the skirt into the plenum for the injection of gas and air. The flameless combustion occurring at the exit surface of the perforated plate makes it a radiant emitter of infrared energy aimed at the bottom of the water tank.

Abstract: An unsintered metal fiber burner is produced by mixing ceramic fibers with the metal fibers and binding the mixed metal-ceramic fibers together as a porous layer adherent to a foraminous support. By mixing ceramic fibers with metal fibers, the cost of a sintered metal fiber burner is reduced while the novel burner, because of the metal fiber therein, exhibits improved properties such as greater radiant efficiency, lower NO.sub.x emissions and increased durability.