ICC Commercial Mechanical Practice Exam

The correct answer is based on the requirements specified in the International Building Code regarding the temperature ratings for smoke dampers. A Class II smoke damper is designed to operate in a fire-resistive environment and help control the spread of smoke through mechanical systems. The minimum temperature rating for Class II smoke dampers is set at 250°F.

This temperature rating ensures that the damper can withstand high heat without failing, which is crucial for maintaining the safety and integrity of the building during a fire event. This 250°F rating reflects the damper's ability to close properly under conditions that may exist in a smoke or fire environment, thereby enhancing the protection against smoke migration within the building.

Higher temperature ratings, such as those suggested in the other options, may apply to specific applications or types of dampers, but for Class II smoke dampers as outlined in the code, 250°F is the baseline standard. Thus, understanding the importance of this rating helps ensure compliance with safety standards and effective smoke control in buildings.