| 摘要 |
PROBLEM TO BE SOLVED: To provide a concentration meter for chemical liquid having a linear characteristic of a relation between a chemical liquid concentration and a conductivity, capable of performing highly accurate concentration measurement continuously, when measuring the chemical liquid concentration of acid or alkali aqueous solution or the like from the conductivity. SOLUTION: A pair of electrodes 11a, 11b for constant-current supply and a pair of electrodes 12a, 12b for voltage measurement comprising a chemical liquid-resistant material, passing the conduit center, and crossing the conduit in the vertical direction to the conduit axis, respectively, are arranged in the conduit 2 for measurement, and the conductivity is measured by a four-electrode method. The ratio S<SB>2</SB>/S<SB>1</SB>of the sectional area S<SB>2</SB>of a vertical surface to the conduit axis of the conduit 2 for measurement to the surface area S<SB>1</SB>of a part in contact with the chemical liquid to be measured per each electrode 12a, 12b for voltage measurement is set to be≥0.8. COPYRIGHT: (C)2008,JPO&INPIT
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