Fire

From TF2 Wiki

Fire refers to the damage over time taken by a player who makes contact with an enemy Pyro's Flamethrower. This is useful for hit-and-run tactics and for weakening or finishing off an opponent, if the damage from the Flamethrower is not enough to kill him or her. This even allows Pyros to score kills when dead, as the fire damage finishes off a wounded opponent.

Upon being set aflame, a player character will automatically scream out that they are on fire, alerting nearby Medics and teammates to their plight. Setting an opponent on fire also creates a disorienting effect on their screen view (flames will engulf the edges of the screen and a burning sound is heard). This can be used to a team's advantage if the Pyro is able to ambush a group of attacking foes.

Fire can be used to carry out Spy checks. A small burst of flame will ignite an enemy Spy, even if cloaked or disguised. If a player is set on fire, you can see particles of the players team color coming from them. This can be very useful because if you see a member of your team on fire, glowing the opposite color, you know they are a disguised spy.

Note that enemy Pyros cannot be set on fire. While a Pyro still takes contact damage from the flamethrower, he will not take further damage over time.

The Fire effect lasts for ten seconds after any contact with a Flame thrower. It damages a player every half-second for 2, 3 or 4 HP each tick. The average total damage from the effect amounts to approximately 60 HP, which is coupled with any direct damage from the Flamethrower's initial attack.

Extinguishing Fire

The following will extinguish a player who is on fire:

• Picking up a health pack
• Completely immersing one's self in a body of water. Puddles and low-level water (such as in the sewer tunnels in 2fort except near the staircase where you may crouch to be submerged) will not extinguish a burning player.
• Being healed by a Medic
• Being healed by an Engineer's Dispenser

Only health packs and jumping into a body of water will remove the burning effect instantaneously. A player briefly continues to burn while being healed by a Medic or Dispenser, although the healing rate exceeds the damage taken over time.