How far from the ceiling should sidewall sprinklers be positioned in an NFPA 13 D system?

In an NFPA 13D system, sidewall sprinklers should be positioned 4 to 6 inches from the ceiling. This specific distance is crucial for ensuring optimal performance when the sprinkler activates during a fire event. When sidewall sprinklers are installed within this range, they are best positioned to effectively distribute water coverage across the area, thus maximizing the cooling and suppression capabilities necessary to control or extinguish a fire.

Installing sprinklers too close to the ceiling could lead to insufficient coverage of the intended area, while positioning them too far may result in water not reaching the necessary height to effectively protect the space below. The 4 to 6-inch guideline is established based on years of research and practical application, ensuring that systems function correctly under real-world conditions.