Does a fire damper need to be installed if a duct is correctly lined with a steel sleeve?

The correct choice indicates that a fire damper may not be necessary if the duct is lined with a sufficiently thick steel sleeve. The thickness and material of the sleeve can provide adequate fire resistance, thereby potentially rendering the installation of a fire damper unnecessary. Fire dampers are primarily utilized to block the passage of flames and smoke through ducts in rated fire barriers, particularly when such barriers need protection from fire exposure.

In systems where ducts are properly lined with materials that can withstand high temperatures and prevent the spread of flames, the rationale is that the inherent properties of the steel sleeve can provide sufficient protection. This concept of using materials and thicknesses that conform to fire safety standards plays a key role in determining if additional components, like dampers, are requisite.

Other options present more stringent requirements. For instance, stating that a fire damper is needed in every case disregards scenarios where the materials and construction already meet safety standards. Similarly, suggesting that only horizontal ducts require a damper is overly restrictive; vertical ducts can also need protection based on the specific building codes and design criteria. Lastly, implying that a damper is only necessary if specified by additional regulations can overlook instances where fire safety principles dictate a need for a damper regardless of code specifications.