Abstract: The present invention lies in a method of improving a Langelier index and pH of city water wherein undissolved matter (calcium carbonate and slaked lime covered with calcium carbonate) slurry produced in a slaked lime dissolving vessel is mixed and reacted with carbonic acid-containing water in a mixing and reacting vessel to make a calcium hydrogen carbonate aqueous solution so as to continuously add to water in a water-receiving vessel together with a slaked lime aqueous solution, with which a utilization percentage of undissolved matter which has hitherto had a low utilization percentage is increased, and the Langelier index can be improved.

Abstract: A method of producing an aqueous solution of slaked lime is disclosed the steps of: introducing water into a slaked lime-dissolving apparatus comprising a dissolving tank, a water supply piping connected to a lower part of the tank, a stirring blade disposed within the tank in its bottom part, an effluent piping connected to an upper part of the tank for discharging aqueous slaked lime solution, and a fluidized slaked lime layer height-control device disposed within the tank above the stirring blade, subsequently introducing a predetermined amount of slaked lime into the tank, feeding water, with low-speed stirring, to the tank from the water supply piping in such a rate that the water in the cylindrical or rectangular upper part of the tank ascends at a rate of from 0.25 to 1.2 mm/sec, and taking out an aqueous solution of slaked lime from the tank through the effluent piping.

Abstract: The Langelier index and pH of city drinking water are improved by mixing and reacting a slurry of calcium carbonate and slaked lime covered with calcium carbonate produced in a slaked lime dissolving vessel with carbonic acid-containing water in a mixing and reacting vessel to make a calcium hydrogen carbonate aqueous solution which in turn is continuously added to water in a water-receiving vessel together with the aqueous solution of slaked lime. As a result, unused undissolved matter is decreased, and the Langelier index of drinking water can be improved.

Abstract: There is disclosed a robot used in a clean room and adapted to transport a wafer cassette containing semiconductor wafers. The robot includes: a guide rail disposed in the clean room; a robot body slidably connected to the guide rail for movement along the guide rail; and a first drive mechanism for driving the robot body along the guide rail. The robot body includes: a clamping hand for releasably clamping the wafer cassette; an arm assembly, extending between the guide rail and the clamping hand, for controlling the position of the clamping hand; and a wrist assembly, interposed between the arm assembly and the clamping hand, for adjusting the orientation of the clamping hand.

Abstract: There is disclosed a dusttight storage cabinet apparatus used for storing works such as wafer cassettes for containing semiconductor wafers. The storage cabinet apparatus includes: a housing having an entrance, formed in its front wall, for allowing works to come in and go out of the housing therethrough; an air supply duct for supplying the inside of the housing with clean air; a vertical rotation shaft rotatably disposed in the housing for turning about its longitudinal axis; a drive motor for turning the rotation shaft; and a rack assembly of a substantially cylindrical structure. The rack assembly is coaxially secured to the rotation shaft and has a plurality of compartments for storing the works therewithin. The compartments open radially outward and are partitioned off from one another so as to prevent cross contamination by dust among the compartments.

Abstract: A driverless guided vehicle movable along a guide path includes a wheel support device for supporting a wheel disposed in rolling engagement with a floor. The wheel support device is resiliently mounted on a body of the guided vehicle for vertical movement relative thereto. A detecting means for detecting the guide path and sensible markings along the guide path is fixedly secured to the wheel support device.