3 main PPV tactics exist according to fire situations :
-OFFENSIVE ventilation tactic:
A direct action on the fire to affect its behavior and reduce its size by ventilating area on fire.
-DEFENSIVE ventilation tactic:
Protects spaces from the fire propagation, smoke and hot gases by ventilating the premisis not reached by the fire yet.
-COMBINED ventilation tactic:
Coupling DEFENSIVE and OFFENSIVE ventilations: Pressurise stairwell with a Master fan at ground floor. Then attack fire by relaying its airflow with a Relay fan at floor of fire.