What is the function of a frangible bulb in a sprinkler head?

The function of a frangible bulb in a sprinkler head is to break when the temperature reaches a specific threshold, allowing water to be released in response to a fire. This bulb is typically filled with a liquid that expands when heated. As the temperature increases due to a fire, the liquid expands until the pressure exceeds the strength of the glass bulb, causing it to shatter. This releases the water from the sprinkler system, providing essential fire suppression immediately at the source of the heat.

While other options touch upon various aspects of sprinkler system functioning, they do not accurately describe the role of the frangible bulb. For instance, the concept of pressure increase leading to the breaking of the bulb is closely related to its functioning; however, the primary activation is temperature-driven rather than pressure-related. Hence, understanding that the frangible bulb's critical component is its sensitivity to heat is essential for recognizing its intended operation in fire protection systems.