FDNY CoF – Fuel-Oil Piping and Storage System (P-98) Practice Test

In the context of flammable gases, the flammable range refers to the concentration of a gas in air that can support a flame. A non-flammable gas mixture with air will not ignite, no matter the concentration, if the percentage of the gas is above a certain threshold.

For many non-flammable gases, it is established that if the concentration of the gas in the air exceeds approximately 12 percent by volume at 14.7 PSIA (standard atmospheric pressure), the mixture will not have a flammable range. This means that combustion is not possible within that concentration, which is important for safety in environments where gases are present.

So, understanding that a non-flammable gas occupies more than this percentage results in non-combustibility is critical for proper safety protocols and regulations regarding gas storage and handling. Thus, knowing that 12 percent is the determining threshold helps ensure compliance with safety standards in various industries.