What is often the first indication of a fire when dealing with a sprinkler system?

In the context of a sprinkler system, the water flow alarm serves as a crucial first indication of a fire. When the system is activated due to heat from a fire, water flows through the pipes, triggering the water flow alarm. This alarm alerts the fire department and building occupants that there is an issue requiring immediate attention.

While other indicators like smoke alarms, heat detectors, and manual alarm pulls can signal the presence of fire, they may not correlate directly with the functionality of a sprinkler system. Smoke alarms and heat detectors detect fire conditions before anything has been extinguished, and a manual alarm pull requires human intervention to signal an emergency. In contrast, the water flow alarm is directly tied to the activation of the sprinkler system itself, making it a timely and reliable indicator of an active fire scenario.