Methane safety hazards

Figure 6-6 Flammability diagram for methane at an initial temperature and pressure of 25°C and 1 atm. Source C. V. Mashuga and D. A. Crowl, Application of the Flammability Diagram for Evaluation of Fire and Explosion Hazards of Flammable Vapors, Process Safety Progress (1998), 17(3) 176-183.

A natural gas wellhead is located 400 m from an instrument control room. The control room is a potential ignition hazard in the event of a leak of natural gas (essentially pure methane). Studies have shown that a suitable safety margin is imposed if the downwind gas concentration is determined using one-half the LFL. For methane this represents a concentration of 2.5 vol. %. 

In fact, coal-bed methane is an explosive hazard in underground mining operations and for safety reasons has traditionally been vented with mines fresh air circulation. Since the 1970s, methane captured from underground mining has increasingly been used to supplement local gas supplies (WEA, 2000). 

SAFETY PROFILE A poison by inhalation. Very dangerous fire hazard when exposed to heat or flame can react vigorously with oxidizing materials. Moderately explosive when exposed to heat or flame. To fight fire, stop flow of gas CO2, dr) chemical, or water spray. See also CARBON MONOXIDE, HYDROGEN, and METHANE. 

Depending upon the polarity of organic soil constituents and/or working place safety arguments, benzene/methanol may be substituted by other solvents, e.g. toluene/dichloro-methane, acetone, ethanol, and others. Future trends point to the application of supercritical extraction fluids (SFE/SFC), thus avoiding hazardous chemicals. 

Methane can accumulate In coal mines, where It Is a hazard because, when mixed with 5% to 1 4% of air. It Is explosive. Also, miners can be asphyxiated by It (due to lack of sufficient oxygen). Dangerous concentrations of methane can be detected readily by a variety of safety devices. 

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