Study Of An Industrial Dissolved Oxygen Meter Calibration System

The industrial dissolved oxygen meter calibration system is mainly aimed at dissolved oxygen meters in power plants,to calibrate the accuracy and precision of dissolved oxygen meters.When the dissolved oxygen content in the water is too high,it will cause corrode the entire steam circulation system,reduce the efficiency of the heat exchange equipment,shorten the life of the equipment and make the unit unable to operate safely and stably.Therefore,the calibration of the dissolved oxygen instrument is of significance to the accuracy and precision of the dissolved oxygen meter.The subject mainly comes from the“Standard gas-based micro-dissolved oxygen meter calibration device secondary instrument inspection system and gas flow design”.The main work of this paper is to design a set of industrial dissolved oxygen instrument calibration system applied in power plant.The system is mainly composed of dissolved oxygen measurement module,PA class current output module,precision resistance output module,calibration module.The dissolved oxygen module provides the voltage required by the polarographic dissolved oxygen electrode,and can test the output characteristics of the electrode The PA class current output module is used to simulate the oxygen electrode to provide PA class current output to the secondary meter of the oxygen meter to be measured The precision resistance output module is the secondary meter which outputs the precision resistance value to the oxygen meter to test its stability and accuracy,including 0 oxygen standard gas(pure nitrogen)and dissolved oxygen is 100μg/L standard gas(nitrogen containing 0.25% oxygen),air calibration to assist.STM32F103 and AD515,AD7705,DAC8551 are used in the calibration system of industrial dissolved oxygen meter to realize high precision measurement and output.The data collected by the system can be sent to the PC through serial port to be displayed in LabVIEW.When testing and calibrating the whole oxygen meter with standard gas,the parameters of gas flow rate,time and so on can be set.The control circuit of each module of the lower unit can communicate wirelessly with the upper unit and execute the corresponding operation according to the upper unit’s command;the gas flow path and the box part can be designed reasonably to reduce the failure rate and carry out the whole machine’s uniform adjustment.After running and debugging this system pA level current output accuracy reached 1%,precision resistance output accuracy reached 0.1%,standard gas calibration in the standard gas measurement accuracy reached 1%,can be calibrated for the dissolved oxygen meter in the power plant,so that the dissolved oxygen meter measurement accuracy and precision to meet the field use requirements.