This paper introduces the system composition, working principle and some shortcomings of the existing verification device for exhaled gas alcohol content detector, and puts forward a system scheme to solve the existing shortcomings.
It also introduces in detail the components, working principle, device innovation of the verification device for exhaled gas alcohol content detector in the new scheme. Significance.
Exhaled Gas Alcohol Detector is the main detection equipment for judging whether a driver drives under the influence of alcohol. It is the only means to issue law enforcement vouchers on the spot. It is necessary to ensure the accuracy and unity of the detection equipment to guarantee the rights and interests of citizens, traffic safety, social stability and the administration of traffic police according to law and fair law enforcement.
Conditions. The traceability of the exhaled gas alcohol content detector is realized by the verification device of the exhaled gas alcohol content detector of the metering department. At present, the calibration device of exhaled gas alcohol content detector used in China consists of main standard device and auxiliary equipment such as micro-sampler, air bag and air pump. The main standard device is MF-3B liquid organic gas distribution device. The device has high accuracy, good stability and easy operation, but it also has some problems: (1) low verification efficiency. Taking the verification of an exhaled gas alcohol content detector as an example, three bags of standard alcohol gas should be allocated for the verification of low, medium and high concentration values at least.
It takes 10 minutes to configure a 10L bag of gas with 1L/min flow rate, and 30 minutes to configure three bags of gas. If the accuracy requirement is not met, the exhaled gas alcohol content detector should be reconstructed. Calibration, some need to be equipped with calibration gas concentration calibration, another 10 minutes. If more than a dozen or dozens of exhaled gas alcohol detectors are calibrated at one time, the calibration workload will be greater. (2) Human factors have great influence. Due to the micro-upgrade of absolute ethanol injection during the configuration process, the operator’s manual error, the tension of alcohol droplets at the needle tip of syringe, the adsorption of valve, the difference of alcohol concentration between upper and lower parts of the device caused by the alcohol molecule itself being heavier than the average air molecule, and the possible errors of the syringe itself will affect the final configuration. Compare the results.
The above shortcomings directly or indirectly affect the accuracy and reliability of the exhaled gas alcohol content detector verification. With the rapid development of economy, the types and quantities of exhaled gas alcohol content detectors are increasing day by day. There are higher requirements for the automation degree and measurement performance of exhaled gas alcohol content detector verification device. The above shortcomings are gradually highlighted. Therefore, it is imperative to solve these shortcomings. With the development of computer technology, sensor technology and PLC technology, it is possible to develop a calibration device to solve the above shortcomings. The principle of the exhaled gas alcohol detector verification device proposed in this paper is shown in Fig.
1. The exhaled gas alcohol detector verification device consists of a gas generator and a gas control device.
The gas generator is composed of zero-grade air generating system and constant temperature alcohol generating system. Fixed volatile alcohol gas is produced by a high-stability constant temperature tank, and the volatile alcohol gas from the tank is taken out by a continuous flow of gas. The gas control device is composed of flow control module, temperature and pressure gas sensing control module, thermostatic element infrared breath alcohol analyzer, PLC data acquisition control module and computer.
The steady alcohol flow is generated by the precise mass flow controller (MFC), and the online alcohol concentration is monitored by the exhaled alcohol analyzer (EBA). The exhaled alcohol analyzer can be calibrated by traceable dry standard mixed alcohol gas. The traceability of exhaled alcohol concentration can be realized and the accuracy of exhaled alcohol detector can be ensured. The device achieves continuous automation of gas distribution through continuous current-carrying gas and diluting gas; achieves automation of concentration verification through built-in alcohol measuring device; compares with standard gas shows that the exhaled alcohol gas fully meets the concentration of exhaled alcohol gas in JJG657-2006 Exhaled Gas Alcohol Content Detector.
Accuracy requirements. In terms of hardware, the zero-grade air generating system consists of two air compressors, one cold-dryer, four-stage filter, on-line pressure regulating valve, FT-IR generator, zero-grade air generator, two stainless steel gas storage tanks and pressure monitoring device. The constant-temperature alcohol generating system is mainly composed of constant temperature tank and alcohol solution. Quantity control module, temperature and pressure gas sensing control module, stainless steel gas pipeline, on-line infrared breath alcohol analyzer and PLC data acquisition, system control module and computer components.
The software part of the exhaled gas alcohol detector verification device to be adopted implements a unified data preservation format, which provides a strong support for the electronic file management of verification data and provides a data basis for docking with paperless certification system.
During the verification process, the verification data can be input into the verification record in real time. When the verification is finished, the verification data of exhaled gas alcohol content detector can be saved in the storage of various media, which provides efficient query support for the verification data management of exhaled gas alcohol content detector. The long-term stability of the exhaled gas alcohol content detector can be correctly judged by inquiring and comparing the multiple verification data of the same exhaled gas alcohol content detector.
Through the statistics of the qualified rate of the exhaled gas alcohol content detector in the same region (brand), we can know the use of the exhaled gas alcohol content detector in this region (brand), and provide data support for the relevant regulatory authorities. The development of exhaled alcohol gas distribution device can improve the accuracy and reliability of measurement standard of exhaled gas alcohol content detector, improve the automatic control degree of exhaled gas alcohol content detector verification, improve work efficiency, and provide a solid and reliable technical guarantee for exhaled gas alcohol content detector measurement.