What is the minimum size for hanger rods used with pipe diameters up to 4 inches?

In fire protection and sprinkler system installations, the sizing of hanger rods is crucial to ensure that pipes are adequately supported and securely mounted, minimizing the risk of sagging or failure over time. For pipes with diameters up to 4 inches, industry standards, such as those set by the National Fire Protection Association (NFPA) and other relevant codes, specify a minimum size for the hanger rods to provide sufficient strength and stability.

The correct choice indicates that a 3/8-inch diameter is the minimum recommended size for hanger rods used with this pipe size. This dimension ensures that the rods can bear the weight of the piping system, including any water or other substances flowing within it, and accommodate any potential stress from movement or thermal expansion.

Using larger diameter rods, such as 1/2 inch or beyond, may be common for larger piping, but for pipes up to 4 inches, a 3/8-inch rod provides the optimal balance of strength and material efficiency. Adhering to these standards helps maintain the integrity of the sprinkler system over its operational lifespan.