MEASURING INSTRUMENT FOR COD OF WATER

• Main Authors: WATANABE KAZUHIRO, SUZUKI HIROCHIKA, OIKE TAKAYASU
• Format: Patent
• Language: English
• Published: 16.01.1992
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; PHYSICS; TESTING

PURPOSE:To automatically measure the chemical oxygen demand quantity (COD) by no-maintenance for a long period by deriving the absorbance of ultraviolet rays by subtracting an attenuation value of a visible light from an attenuation value of ultraviolet rays allowed to transmit through water which is led into a transparent cylindrical body by a wiper. CONSTITUTION:A case 1 is suspended into the water of a prescribed depth by a cable 12, a wiper 5 is allowed to ascend by a motor 7 and water is led into a water cylinder 4, and whenever the wiper 5 ascends, a measurement is repeated. Subsequently, from the photoelectric tube 21, and a photoelectric tube 27, an attenuated ultraviolet-ray output, and a reference light are inputted to a divider, respectively through amplifiers 34a, 34b, BPFs 35a, 35b, and rectifying circuits 36a, 36b, respectively, and by deriving a ratio of the attenuation light and the reference light, and inputting it to a logarithmic amplifier 38, the ultraviolet-ray attenuance Auv is outputted. In the same way, a visible light and a reference light of an LED 28 are also amplified 39a, 39b, respectively and inputted to a logarithmic amplifier 43 and the visible light attenuance Avis is derived. Next, a difference of the attenuances Vuv, Vvis derived by a computing element 44 becomes the ultraviolet-ray absorbance absorbed by organic matter which eliminates an attenuation caused by suspended matter, therefore, it is converted to the COD from this value.