Please note this resource contains archived content only. Please visit https://msasafety.com to search and explore the newest content available.
If you are an MSA Channel Partner or MSA Associate, please login to view secure information.
In the Know
  • Fixed Gas & Flame Detection Fixed Gas & Flame Detection
Do you know the three conditions that must be met for a combustible atmosphere to exist? Read on to find out.

In order for a combustible atmosphere to exist, three conditions must be met. There must be:

  1. A source of fuel (e.g., methane or gasoline vapors)
  2. Enough oxygen (greater than 10-15%) to oxidize or burn the fuel
  3. A source of heat (ignition) to start the process

Atmospheres in which the gas concentration level is below the lower explosive limit (LEL) are referred to as too “lean” to burn, meaning there is insufficient fuel to ignite. Those in which the gas level is above the upper explosive limit (UEL) are too “rich” to burn as they have insufficient oxygen to ignite.

Now you’re in the know. Learn more about combustible atmospheres and other gas detection principles in our Gas Detection Handbook.