When can methane gas become both explosive and flammable?

Methane gas becomes both explosive and flammable when it is mixed with atmosphere (air) or oxygen. This mixture can create an explosive atmosphere, as methane is a highly combustible gas. When methane is in the right concentration with oxygen present, it can ignite easily and lead to combustion.

The flammability of methane allows it to catch fire readily, and under certain conditions, the rapid expansion of gases from the explosion can create destructive pressure waves. The specific range of methane that can be considered flammable and explosive in air is approximately 5% to 15% by volume. This range is known as the lower explosive limit (LEL) and upper explosive limit (UEL).

In contrast, while high temperatures can promote ignition and high-pressure storage can increase the risk of leaks, these factors alone do not inherently create an explosive or flammable situation without the specific mixing with air or oxygen. Dissolving methane in water does not create flammability, as methane is only sparingly soluble in water and does not produce the necessary gaseous mixture that can ignite.