What does the term "flammable range" refer to in hazardous environments?

The term "flammable range" specifically refers to the area between the lowest and highest concentrations of gas or vapor in the air that can ignite when exposed to an ignition source. This range is critical for understanding the potential hazards present in a confined space environment where flammable gases might be present.

In practical terms, knowing the flammable range allows responders and safety personnel to assess whether the atmosphere is safe for entry or if mitigation measures are necessary. If the concentration of a flammable substance is below the lower limit of the range, it is too lean to ignite, meaning there isn't enough fuel. Conversely, if the concentration exceeds the upper limit, the mixture is too rich to ignite. Therefore, identifying this range is essential to prevent explosions and fires in confined spaces.

The other options do not accurately define what the flammable range represents and instead pertain to different safety considerations within hazardous environments, such as oxygen levels and distance safety measures. Understanding the flammable range is a foundational element of safety protocols in confined space operations.