What is the explosion limits for natural gas?

The explosion limits for natural gas, known as the lower explosive limit (LEL) and upper explosive limit (UEL), define the concentration range of natural gas in air that can lead to combustion or explosion if an ignition source is present. The correct range is from 4% to 15% by volume in air.

At the lower explosive limit of 4%, there is not enough gas to sustain combustion; below this concentration, the mixture is too lean. At the upper explosive limit of 15%, there is too much gas, which makes the mixture too rich to ignite. Therefore, the correct response captures both the minimum and maximum concentrations necessary for natural gas to pose an explosion risk when mixed with air. This is essential knowledge for safety protocols in environments where natural gas is present, to prevent potential hazards associated with combustion.