Ordinary classification corresponds to a maximum ceiling temperature of?

Ordinary classification corresponds to a maximum ceiling temperature of?

• A. For temperatures up to 225°F (107°C)
• B. For temperatures up to 300°F (149°C)
• C. For temperatures up to 170°F (77°C)
• D. For temperatures up to 200°F (93°C)

Answer: (C)

The key idea is that ordinary classification is tied to the maximum ceiling temperature the system is expected to handle. In NFPA 13R for low-rise residential buildings, ordinary environments assume ceilings won’t exceed 170°F (77°C). Sprinklers selected for ordinary classification are rated to operate reliably up to that temperature, which matches typical living-space conditions. If the space could reach higher ceiling temperatures, you’d use sprinklers rated for those higher temperatures (such as 225°F or 300°F), which are not part of the ordinary classification.

The key idea is that ordinary classification is tied to the maximum ceiling temperature the system is expected to handle. In NFPA 13R for low-rise residential buildings, ordinary environments assume ceilings won’t exceed 170°F (77°C). Sprinklers selected for ordinary classification are rated to operate reliably up to that temperature, which matches typical living-space conditions. If the space could reach higher ceiling temperatures, you’d use sprinklers rated for those higher temperatures (such as 225°F or 300°F), which are not part of the ordinary classification.