Furnace oil, also known as fuel oil or heating oil, is a heavy petroleum-based product primarily used in industrial furnaces and boilers to generate heat. It's a residual product obtained after refining crude oil, making it one of the heavier products from the distillation process.

Primary Characteristics:

Appearance: Viscous liquid, typically dark brown or black.
Odor: Distinctive petroleum-based aroma.
Density: Heavier compared to light distillates like gasoline and diesel.
Sulfur Content: Can vary, but certain grades have a high sulfur content.

Specifications:
The quality and grade of furnace oil are often specified by standards such as ISO or regional standards. It's typically classified by its viscosity and sulfur content.

Applications:

Industrial Heating: Used in large furnaces, kilns, and boilers in various industries.
Power Generation: Some power plants operate on furnace oil, especially during peak demand or when other fuels are unavailable.
Marine: Older ships and certain marine vessels use furnace oil as a bunker fuel.

Advantages:

Cost-Effective: Often cheaper than other fuel types, especially in regions with abundant refineries.
High Energy Content: Its dense nature means it carries a significant amount of energy per unit.
Availability: Commonly available due to the vast global crude oil refining processes.