What is the function of a riser in a sprinkler system?

The riser in a sprinkler system serves the critical role of transporting water vertically through a building. This component is essential for effectively delivering water from the main supply to the various branches and sprinkler heads located throughout the floors and different levels of a building. By enabling vertical movement, the riser ensures that all areas, regardless of elevation, can receive the necessary water supply in the event of a fire. This vertical capability is crucial for maintaining adequate pressure and flow rates as the water ascends to upper floors, facilitating the overall effectiveness of the fire suppression system.

The other options describe functions not associated with the primary role of a riser in a fire protection system. Collecting rainwater, storing excess water, and diverting water to drains are activities typically related to different components or systems entirely, such as drainage systems, collection tanks, or rainwater harvesting solutions. These are not integral functions of the riser in a sprinkler system.