From Lexicanum

The Inferno Cannon is a huge, vehicle mounted flame weapon. It is used by the Imperial Guard on the Hellhound tank and can be taken by Space Marines as an alternate weapon choice on a Dreadnought. The amount of damage it does is magnified by the explosive force it is fired with. It causes fear amongst those enemies that face it, and rightly so. The sheer amount of flame that leaves the vehicle is immense, enough to melt through most armour and even some defensive structures. The tank has to carry large barrels of Promethium, making it extremely volatile, especially under explosive fire.

When it fires, the vehicle must not be moving, as a disastrous back wash of flame would fry everyone inside the vehicle. The crew are often seen as pyromaniacs.

The Immolator tank of the Sisters of Battle uses twin-linked Heavy Flamers which produces a similar effect.

Sources

• 3rd Edition Rulebook
• Codex: Imperial Guard (3rd Edition, 1st Codex)
• Codex: Imperial Guard (3rd Edition, 2nd Codex)

Flame Weapons

Imperium	Brazier of Holy Fire • Combi-Flamer • Exterminator • Flamer • Heavy flamer • Inferno cannon • Inferno gun • Incinerator
Chaos Space Marines	Combi-Flamer • Flamer • Heavy flamer
Tau	Flamer
Orks	Burna • Kombi Shoota-Skorcha • Scorcha
Eldar	Dragon Breath Flamer • Flamer