DEVICE FOR ADJUSTING RESISTIVITY VALUE OF PURE WATER

摘要

PROBLEM TO BE SOLVED: To provide a device for adjusting a resistivity value of pure water which is small-sized and is easy to operate and whose control mechanism is simple. SOLUTION: This device 10 for adjusting a resistivity value of pure water is the one in which gaseous CO2 is introduced into a hollow fiber membrane module to dissolve the gaseous CO2 in pure water flowing in a vessel to adjust resistivity of the pure water. The device 10 is provided with a hollow fiber membrane module 14 and a closed vessel 12 which incorporates the hollow fiber membrane module 14 and in which pure water flows outside the hollow fiber membrane module 14. The hollow fiber membrane module 14 has a lot of bundles of hollow fiber membranes 20 consisting of gas permeable membranes. Gaseous CO2 passing through a hollow part inside the hollow fiber membranes is made to permeate into outside of the hollow fiber membranes. In this device 10, a pressure adjusting valve 34 and a flow adjusting valve 36 for adjusting the pressure and flow of gaseous CO2 fed to the hollow fiber membrane module 14 respectively are provided on a gaseous CO2 feed pipe 28.