Design and application of the municipal sewer combustible gas monitoring system based on remote radio-sensing network

The paper is to introduce its author' s work on designing and application of the municipal sewer combustible gas monitoring system by means of the remote radio-sensing network technology. As is known, the concentrations of all combustible gases and the different nodes can be made to be monitored through remote on-line sensing monitoring by using a visual chart and a warning-prompt device. The results gained through careful measurement and inspection indicate that all-the-year around successful sending rate can reach 98.0% , with the relative deflection error reduced to less than 2% , with high reliability and stability. Based on the above technical reality, this paper is engaged in designing a remote on-line monitoring system for safety control and early warning of urban municipal sewer as a sort of supervision platform. The monitoring system is composed of a gas sensor module, a signal processing module, a data transmission module and a supervision center. For convenience, the infrared sensor has been set up at the head of the inspection well where the combustible gas (mainly methane) is most likely to congest. Since the sensor is highly sensitive to the response the moment the gas concentration reaches the minimum explosion point, the sensor would send an analog signal and then convert it from the concentration into a digital signal and then into an electrical signal. The signal can then be transmitted to the supervision center by the data transmitting unit (DTU) of the GPRS which is on guard against the explosion hazard state for all the year around. The instant the combustible gas gets to the explosion brink, the municipal sewer would in time deliver a warning signal and inform the system operator of the hazard before the explosion would occur. When the warning and location are informed of the hazard by the sensor, the system operator would send an emergency signal in-situ to dilute the gas concentration. In this way, the hazard of the gas explosion in the sewer can be expected to get avoided. The results measured in our experiments indicate that all-theyear -running successful sending rate of GPRS-DTU can reach 98.0% , with the relative deflection error of the gas sensor reduced to below 2 % . The system can thus be expected to satisfy the demands for engineering application at high reliability and stability. Furthermore, the remote-sending monitoring system can be used in different regions to achieve combined effects with the features of wide coverage, real-time online of wireless network. Thus, the construction of such a monitoring system can be said to provide an effective basis for preventing the explosion likely to be caused by the combustible gas accumulation in the municipal sewers.