By Alex Langbell
Photos courtesy of Yakima (WA) Fire Department
It is rare to see a single smoke color coming from a structure, but by paying attention to the color, velocity, volume and density, you can gather some clues to help you locate the fire, identify the stage of the fire and what it is that is possibly burning. As solid materials first start to burn they emit white smoke which is moisture from the object, as it dries it changes colors. If the smoke turns brown or tan it usually means wood materials are burning, possibly the structure itself. If it turns gray it is either a plastic or painted/stained surface. Eventually, as the product burns, the smoke will turn black. As the smoke is carried away and the smoke particles drop, the smoke turns gray and eventually white. When flames touch a surface the off gas is black smoke.
|White||Incipient stage/Smoke with fewer carbon particles/extinguishment|
|Gray||Plastics/ Painted/stained surfaces in initial stages of burning|
|Tan/Brown||Wood product in initial stages possible structural involvement|
|Black||Hydrocarbons/Materials in the later stages of burning|
Things to remember:
- The hotter it is, the blacker the smoke.
- The denser the smoke, the bigger the flashover/fire spread will be.
- A firefighter crawling through zero visibility smoke is crawling through ignitable fuels.
- The faster and darker the smoke, the closer to the seat of the fire it is.
- You should see distinct differences in velocity and colors from different opening.
- If the smoke is uniform from all openings, expect fire to be in a concealed space or deep seated.
This is an abbreviated version from a great article written by David W. Dodson for Fire Engineering. To read the entire article, CLICK HERE.
Alex Langbell is a captain with the Yakima (WA) Fire Department.