What is the function of an arm-over in a sprinkler system?

In a sprinkler system, an arm-over serves the specific purpose of extending from the branch line to a single sprinkler head. This configuration is essential for directing water flow from the branch line into the sprinkler, ensuring adequate coverage and pressure for effective fire protection. The design of the arm-over allows it to effectively position the sprinkler in the required location while facilitating optimal operation.

When considering the other options, they do not align with the defined function of an arm-over. For instance, connecting two main lines directly pertains to a different type of fitting not described as an arm-over. Supplying water to multiple branch lines or acting as a main feed line implies a broader distribution role that is not specific to the function of an arm-over, which is focused solely on individual sprinklers. Understanding this specific role helps clarify the integral components of a sprinkler system and their functions.