SPECIFIC-RESISTANCE ADJUSTING METHOD FOR ULTRAPURE WATER AND ULTRAPURE-WATER TREATMENT DEVICE

摘要

Disclosed is a specific-resistance adjusting method for ultrapure water used for adjusting the specific resistance value of ultrapure water by dissolving carbon dioxide in the ultrapure water, which comprises supplying carbon dioxide to a motor-driven rotary valve while adjusting the pressure of the carbon dioxide; supplying the carbon dioxide to a gas-liquid contact chamber in accordance with the number of revolutions of the motor-driven rotary valve; measuring the specific resistance value of ultrapure water discharged from the gas-liquid contact chamber; adjusting the number of revolutions of the motor-driven rotary valve by feeding the measured specific resistance value back; and keeping the specific resistance value of the ultrapure water after the carbon dioxide is dissolved in the range of 0.2 to 1.0 MO·cm. Also disclosed is an ultrapure-water treatment device that is preferable to the specific-resistance adjusting method.