AUTOMATIC MEASURING DEVICE FOR CHEMICAL OXYGEN DEMAND AND METHOD FOR USING SAID DEVICE

PURPOSE:To know the operating condition of an automatic measuring device for chemical oxygen demand (COD) by measuring automatically an oxidation reduction potential difference (ORP) over the entire stage of the automatic COD measuring cycle by using said automatic measuring device and comparing the pattern of the record obtd. by such measurement with the preliminarily determined patterns in the normal stage and abnormal stage. CONSTITUTION:The positions of a Pt electrode 12 and reference electrode 13 of an ORP meter of a COD A-112 type measuring device are adjusted at the same level X of the level of the top end of a discharge pipe 14. The COD of certain waste water is automatically measured by using the COD measuring device which is adjusted in the positions of the electrode ends in the above-mentioned way. The figure illustrates the graph indicating the change with time of the ORP indication corresponding to the measuring stage. The automatic recording of the ORP is approximately a repetition of the pattern shown in the figure when the measuring device operates normally. The pattern different from the pattern in the normal stage is obtd. on the contracy when abnormality arises in any part of the stage. The operator is therefore able to identify easily and quickly in which part of the cycle of the automatic COD measuring device the problem arises by viewing the pattern of the automatic recording for the ORP.