Which of the following is defined as a flammable gas?

A gas is classified as flammable when it can ignite easily when mixed with air under specific conditions. The correct choice identifies a gas that is ignitable when mixed with air at a concentration of 13% by volume at a temperature of 68°F. This particular mixture is significant because it falls within the flammability limits; typically, gases that are flammable have a minimum concentration in air below which they cannot form an ignitable mixture. The value of 13% volume in air indicates that, at this concentration, the gas contains enough fuel to support combustion when exposed to an ignition source.

The focus on the condition of being at a temperature of 68°F further emphasizes the practical scenarios in which such gases would be encountered in typical environments, such as inside facilities where healthcare and medical gases are utilized. Understanding these parameters is vital for maintaining safety protocols in environments where medical gases are present, as it ensures proper handling and minimizes risks associated with fire hazards.

In contrast to this, other options do not accurately describe characteristics that would classify a gas as flammable. For instance, describing a gas as ignitable only under high pressure or not ignitable at atmospheric pressure does not align with the standard definitions of flammability, as it overlooks crucial temperature