Design And Implementation Of Verification System Based On Piston Liquid Flow Standard Device

Flow measurement is of great significance in ensuring product quality,improving production efficiency,and promoting technological progress,and has always been highly valued by governments and enterprises in various countries.With the introduction of mandatory verification policies for measuring instruments such as water meters and heat meters,flow verification devices have become a research focus for measurement units in China.With the development of testing and automation technology,the standard devices used today,such as the mass method,volumetric method,and standard meter method,have many limitations such as low calibration efficiency,low automation level,and large volume,and urgently need new breakthroughs.This thesis has designed a highly automated,efficient,and accurate calibration system for piston liquid flow standard devices,achieving automated calibration of ultrasonic water meters to meet the current calibration needs of household ultrasonic water meters.Firstly,determine the overall design scheme of the calibration system for the piston liquid flow standard device.Operation of standard piston fluid delivery devices the actual verification of the flow range of the ultrasonic water meter in this thesis,the design concept and technical indicators of the flow standard device are proposed,and a mathematical model of the piston standard device is established.The size design of the piston device is completed.Select the main components such as water pumps,servo motors,servo drivers,encoders,etc.in the hardware equipment.The overall structure of the piston liquid flow standard device has been designed.We have determined the automatic control scheme for the flow standard device calibration system,designed communication protocols between the control system,ultrasonic water meters,and programmable logic controllers(PLC),and achieved communication between the control system and equipment.Then,to achieve automatic verification of ultrasonic water meters in the system,a flow verification system was designed to perform pressure testing,exhaust,and vacuum extraction before the water meter verification;Designed an overall calibration control algorithm for the flow calibration system,a water meter flow point calibration algorithm that combines the start stop method with the dual time method,and a water meter flow correction algorithm;We have developed an automated flow verification control system that is compatible with the piston liquid flow standard device,improving the efficiency of calibrating ultrasonic water meters.Finally,calibration experiments,performance testing,and uncertainty evaluation were conducted on the developed piston device.The experimental results showed that the device’s performance was stable and the repeatability was better than 0.02%.By describing the implementation process of the flow calibration system,the rationality of the automatic calibration algorithm for ultrasonic water meters was verified.The experimental results show that the flow error of the ultrasonic water meter after flow correction does not exceed ±3%in the "low zone" and ±2%in the "high zone",with repeatability less than 0.05%.The automatic verification system for the piston liquid flow standard device designed in this thesis has practical value of high verification accuracy and efficiency,meeting the production needs of enterprises.Flow measurement is of great significance for ensuring product quality,improving production efficiency,and promoting the development of science and technology.It has always been highly valued by governments and enterprises in various countries.The country has introduced a mandatory verification policy for measuring instruments such as water meters and heat meters.The flow verification device is a research focus of measurement units in China.With the development of testing and automation technology,the commonly used standard devices such as mass method,volumetric method,and standard meter method have many limitations such as low efficiency,low automation level,and large device volume,which urgently require new breakthroughs.This thesis designs a flow standard device and control system for ultrasonic water meters with high automation,verification efficiency,and accuracy to meet the current verification requirements for ultrasonic water meters.