ULC labs test fire dampers from _____ hour to _____ hour rating.

ULC (Underwriters Laboratories of Canada) tests fire dampers to ensure they meet specific standards for fire resistance. The ratings indicate the ability of a fire damper to withstand exposure to fire for a specified period before failing. The correct range for the fire ratings of dampers tested by ULC is from 1.5 hours to 3 hours. This range reflects the various standards and applications in which these dampers might be used, particularly in commercial and industrial settings where fire safety is critical.

The lower limit of 1.5 hours ensures that these dampers can effectively help to prevent the spread of fire and smoke through duct systems for a significant period, while the upper limit of 3 hours indicates a higher level of fire resistance suitable for more demanding conditions. This testing is imperative for compliance with safety regulations and building codes, ensuring that proper measures are in place to protect occupants and property in the event of a fire.