What is the maximum unsupported horizontal length between the end sprinkler and the last hanger for a 4" main?

The maximum unsupported horizontal length between the end sprinkler and the last hanger for a 4" main is set at 60 inches to ensure adequate support and structural integrity of the piping system. This specification is critical because a longer unsupported span could lead to sagging, misalignment, or even failure of the sprinkler system, affecting its performance during operation.

Proper support is crucial in fire protection systems, as it helps maintain the correct positioning of the sprinkler heads and ensures that the pipes can handle the pressures they will encounter. The 60-inch limit is consistent with industry standards and guidelines, which dictate how far sprinklers can be from their supporting structures to avoid issues like bending or fracturing of the pipe material over time.

Understanding this requirement is essential for ensuring the effectiveness and reliability of fire protection systems installed in various buildings.