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

The function of a riser in a standpipe system is to vertically distribute water to different floors of a building. This vertical component allows for the effective delivery of water to various levels within a structure, ensuring that each floor has the necessary access to water for firefighting purposes.

Risers are typically positioned in stairwells or other accessible locations to enable firefighters to easily connect hoses and receive water from the building's water supply. By providing a vertical conduit for water, risers facilitate the quick and efficient response to a fire situation by allowing fire suppression teams to combat flames on multiple floors without needing to draw water from the ground level.

In this context, other options do not accurately describe the primary function of a riser. While other components of the standpipe system may perform tasks such as pumping water, connecting hose lines, or monitoring pressure, it is the riser's specific role in vertical water distribution that is crucial for effective fire suppression in multi-story buildings.