Soot from oil burner

Tom_12

I have been working with an oil burner mechanic this season doing some cleanings. I noticed that some of the units have different colored soot. Some dark black, some brown soot even one that look sort of gray and almost red. What can cause burners to produce different colored soot? Could it be the dye in the oil?

J.C.A.

Soot coloring/ oil

Black= bad fire . Not enough air to burn the quantity of fuel being introduced .Something often overlooked are dirty vanes on the blower fan ! Simple , but forgotten.

Light brown = over aired burner , in most cases . If while performing a smoke test you don't see something on the paper, lower the air band till you get a trace , then open and adjust for CO2/O2.

Red and Yellow tend to be found in boilers that are cold start units . Moisture finds its way into the boiler and when fired , the drying results in "bubbles" . Depending on the stuff the water had in it ....yellow is usually sulpher .(that acrid smell of burning matches on light off till draft is stablized ) Red can be rust scrubbed down from the top of the boiler sections. No smell, but kind of weird to see bubbles just "snap" and leave marks like an old barnicle was there .

Some other things that will effect the color of "by products of burning fuel oil" (soot is such a nasty word) are the quality of air in the area and chemicals nearby .
The only way to avoid these phenomina is to TEST ! Every service should be finished with a combustion efficentcy test . The instruments have no reason to lie , why not trust them . Hope that helped . Chris

Jim Davis

Soot colors

Black is normal soot. Red coloration is an indication of sulfur(normally it is flakey) and is normal. Gray or white soot is caused from underfiring and producing higher levels of CO(200-400ppm)and then tying up with the moisture in the flue gas because of low temperatures.

J.C.A.

Jim...

I don't want to split hairs , but ... Black soot is normal ?

Any soot is an anomoly . . With the controls that are available to the oil field now, proper testing should be the end of "normal soot" .

The observations that I stated have come from many years of "hands on" experience , and the results of my trustworthy equipment .(doesn't under fired =over-aired?) The dye being used in home heating fuel has been used as an excuse for a pile of problems , but personally I feel that the only thing it's done is to show leaks a little faster .Red draws attention , but also helps in finding SOME problems . (leaky seals and the like)

The point I was trying to stress is to TEST all alterations to any equipment . I will always feel that this is the most important , yet under accomplished task in the field.

Again , the instruments don't have anything to hide , trust them . Chris

Jim Davis

Black Soot

I have got lots of hairs to split. No soot is not normal. But when soot occurs it will normally be black.
Underfiring can occur with minimum air or excess air.
Overfiring can occur with excess air.