Above 0.50 meters water depth, the system implements full temperature-based autonomous behavior, where fire threat conditions rather than water availability determine defensive actions. This temperature-based logic operates in two distinct phases—warmup and cooldown—representing different stages of a fire event.
Warmup phase represents the assumption that fire is approaching or intensifying. The phase begins at system startup or whenever the cooldown detection criteria are not met. When external temperature exceeds 80 degrees Celsius, the system activates continuous sprinkler operation with the high flow valve P3 open, providing maximum water delivery to defend against an imminent or present fire front. The 80-degree threshold was chosen based on radiant heat studies showing that at this external ambient temperature, radiant heat from an approaching fire is sufficient to cause ignition of combustible materials even without flame contact.
Between 75 and 80 degrees Celsius, the system runs intermittent sprinklers with a cycle of five minutes on, three minutes off. This represents a transition zone where fire is close enough to require active defence but not yet at maximum intensity. The relatively short off time (three minutes) ensures that surface cooling doesn't completely dissipate between cycles, maintaining some protection throughout the interval.
Between 60 and 75 degrees Celsius, the cycle extends to three minutes on, seven minutes off. At these temperatures, fire is approaching but still distant enough that conservation becomes more important than continuous cooling. The seven-minute off time allows significant water savings while the three-minute on time provides periodic protection against ember ignition and surface preheating.
Below 60 degrees Celsius during warmup phase, no sprinkler activation occurs—the fire is too distant to justify water usage, though the system remains in a ready state, monitoring temperatures continuously and prepared to activate when thresholds are crossed.
The transition from warmup to cooldown phase represents a critical decision point in the fire event timeline. Cooldown indicates that the fire front has passed or is retreating, and that defensive water usage should wind down accordingly to preserve remaining resources. The system detects cooldown by monitoring both external and internal temperature trends over a five-minute window (shortened to one minute on TestSys hardware to accelerate test scenarios).
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