MANUFACTURE OF LEAN SOLUTION AND ITS DEVICE

摘要

PROBLEM TO BE SOLVED: To unnecessitate a large tank and a pump for adjusting a density and to stably supply a mass of lean solutions by providing a valve unit where a fluit passage area is variable step by step in a main duct. ;SOLUTION: When an electromagnetic valve 5 and a manual valve 6 are opened and extrapure water is supplied to the main duct 1 by a fixed supply quantity, a flowrate sensor 7 and a pressuresensor 8 detect the flowrate and the pressure so as to transmit measurement result to a process controller 18, the supply pressure of the pump is controlled and extrapure water is supplied at the prescribed flowrate and under the pressure. 50% hydrofluoric acid is injected from a branch pipe 2 to the main duct 1 with a digital valve unit 14 by the pressure being higher than that of the main duct 1. A density sensor 17 measures the density of HF water which is adjusted in density and supplies the result to an arithmetic device in the process controller 18. When the measurement result exceeds a prescribed error range so as to be high, the arithmetic device of the process controller 18 adjusts the opening degree of the digital valve unit 14.;COPYRIGHT: (C)1999,JPO