The US. Code of Federal Regulations (Title 30) requires that a methane monitor be placed on every mining machine to continuously observe and record methane levels at the face. The monitor must provide a warning whenever methane levels are 1.0 percent or higher. An effective monitoring system will indicate a methane concentration of 1.0 percent on the mining machine before methane levels at the mining face reach 5.0 percent Where the methane monitor is located on the mining machine is one of the most important factors that determines how effectively face methane levels can be predicted Any change in the sampling location will result in a change in measured methane concentration. To protect the methanometer it is usually located on the cutting boom at least 1 to 1.8 m (3 to 6 ft) out by the front cutting bits. A face ventilation system using blowing tubing was simulated in a full-scale test facility. Methane released from the face area was monitored at multiple locations on a model-mining machine as well as locations near the face. Based on the relationship between concentrations measured on the machine and at the face, criteria were developed for selecting the best machine locations for monitoring methane. Recommendations are given for revising methane action levels for alternative sampling locations.
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