Gas detector is an instrument tool for detecting gas leakage concentration, mainly referring to portable/handheld gas detectors. Mainly using gas sensors to detect the types of gases present in the environment, gas sensors are sensors used to detect the composition and content of gases. It is generally believed that the definition of gas sensors is based on the classification of detection targets, which means that any sensor used to detect gas composition and concentration is called a gas sensor, regardless of whether it uses physical or chemical methods. For example, sensors that detect gas flow are not considered gas sensors, but thermal conductivity gas analyzers are important gas sensors, although they sometimes use generally consistent detection principles.
As early as the 1970s, gas sensors had become a major family in the field of sensors, belonging to a branch of chemical sensors.
One reason is that the readings of the main controller and the on-site detector do not match during calibration. In general, combustible gas alarms are connected by a separate line system between the main controller and detectors. The detectors are distributed across multiple monitoring points, and the main controller centrally controls them. The gas concentration of each detector is displayed independently. When the gas concentration of the detector in the environment reaches or exceeds the preset alarm value, the main controller will issue an alarm to remind the on duty personnel to take safety measures and ensure the safety production of the enterprise. During on-site calibration, the author often found that the readings of the main controller and the on-site detector were far apart, causing the calibration personnel to not know how to judge whether the instrument was qualified. The author believes that if this situation is discovered, the zero point and range potentiometers of the main controller should be adjusted, and the output of the probe should be related to the gas concentration. If it is not qualified, it should also be adjusted. The main controller can display the detectors on site separately, which means they can be adjusted separately. If only adjusting the values on the detector ignores the values on the main controller, then the main controller will be meaningless and will not have any monitoring function.
The second is the calibration cover used for verification. According to the verification regulations, diffusion instruments should have calibration covers, and each manufacturer has their own calibration cover. However, in actual verification, the inspector will use self sealing bags and self-made calibration covers instead. I think it is better to use the original factory's calibration cover as much as possible, because the internal air and air intake methods (bottom air intake and side air intake) of the calibration cover still have a certain impact on the response time and indication error of the instrument. Of course, when verifying combustible gas alarms, regardless of the type of calibration cover used, one principle must be adhered to, which is to strictly prohibit the calibration cover from being too tight and not having an overflow port to generate positive pressure, as this will affect the verification results. It is also strictly prohibited to loosen too much, which may cause external gas to enter and result in the actual value of the standard gas being too small, affecting the calibration results.
The third requirement is good ventilation. For open combustible gas diffusion and escape, if there is a lack of good ventilation conditions, it is easy for the combustible gas content in a certain part of the air to approach or reach the lower explosive limit concentration, resulting in inaccurate calibration results.
Fourthly, there is no interference from the tested component. Attention should be paid to preventing electromagnetic interference during the verification of combustible gas alarms. The main influencing factors of electromagnetic environment on combustible gas detectors are as follows: human static electricity, narrow pulse groups on power and other input and output lines, and airborne electromagnetic wave interference.
Nanjing Huanan Intelligent Technology Co., Ltd. is a high-tech enterprise that integrates the research and development, production, and sales of intelligent instruments and meters. The company's development direction is to achieve remote monitoring of traditional detection and analysis instruments through the Internet of Things.
Since its establishment, the company has completed the development and testing of remote monitoring systems for chemical testing instruments, remote monitoring systems for oil fume detection, and wireless local monitoring systems for pesticide detection in grain and tobacco depots, which have been recognized by society and relevant personnel.
The company will continue to move towards high directions and goals, and contribute to a better life for humanity in the future!