Fuel Oil Characteristics - continued.

Approximate elemental constituents of No. 6 oil are:

Hydrogen: 10.45%

Carbon: 85.95%

Sulfur: 2.3%

Nitrogen: 0.3%

Oxygen: 0.98%

Ash: 0.03%

Moisture: negligible

Ash Content

Lighter oils have no ash, while heavier oils may contain as much as 0.08% ash. The term "ash" refers to inorganic substances which cannot be burned but create a powdery residue.