How far must a hanger be from a horizontal main after a riser?

The correct distance for a hanger from a horizontal main after a riser is 2 feet. This requirement is rooted in ensuring proper support and stability for the piping system. The 2-foot rule helps to prevent sagging or shifting of the piping, which can lead to stress, possible leaks, and inefficiencies in the sprinkler system's performance.

Adequate support is crucial for maintaining the integrity of a fire protection system, and by adhering to this spacing standard, sprinkler fitters can promote safe and reliable operation. This guideline is often based on industry standards and best practices, which emphasize the importance of secure and well-supported piping installations.

In summary, the requirement of having the hanger 2 feet from a horizontal main after a riser is critical for the overall performance and safety of the sprinkler system.