Non-flammable gases do not have a flammable range with air of at least what percentage at 14.7 PSIA?

Non-flammable gases are defined as gases that do not ignite and burn in air under standard conditions. The concept of flammable range refers to the concentration of gas in air that can support combustion. For a substance to be considered non-flammable, it must not have a flammable range with air below a certain percentage.

At 14.7 PSIA (which is standard atmospheric pressure), a non-flammable gas does not form a mixture with air that is capable of sustaining combustion if the concentration of the gas is less than 12 percent. This threshold indicates that concentrations equal to or greater than 12 percent may lead gas to become flammable in the presence of an appropriate ignition source.

Thus, the correct answer indicates that non-flammable gases must have a flammable range with air that is at least 12 percent, as anything below that concentration will not ignite or burn. This establishes a safe guideline for dealing with various gases in practical applications, ensuring proper handling and storage practices to avoid fire hazards.