Design and implementation of safety monitoring and warning system of toxic and flammable gas for municipal sewer pipe based on Nios-II and GPRS

To improve the reliability and real-time performance when monitoring the urban municipal swear gas, a security monitoring and early warning system for sewer gas was developed and used in Chongqing City. The system is a sort of remote, on-line supervision platform for sewer gas monitoring based on general packet radio service(GPRS), comprising sensor module, signal processing module, data transmission module and supervision center layer. The location of municipal sewer in which the combustible gas(mainly CH₄) concentration exceeds the explosion limit can be displayed in time and correctly. The annual successful sending rate reaches 99.3%, and the relative deflection error is restricted within 1%. The construction of the monitoring system provides an effective basis for preventing the explosion and poisoning caused by the combustible gas leakage in the sewers.