In what scenario are smoke dampers not required in corridor penetrations?

Smoke dampers are critical fire protection devices used to prevent the spread of smoke through ventilation systems. However, there are specific scenarios based on building codes where smoke dampers may not be necessary. In the scenario presented, the thickness of the duct plays a pivotal role in determining the need for smoke dampers.

When a duct is made of steel with a thickness of at least 0.019 inch, it is typically classified as having sufficient material integrity to withstand a reasonable level of exposure to fire without allowing smoke to penetrate into the protected area. The minimum thickness specification helps in ensuring that the structural capability to contain smoke is met, thereby negating the need for smoke dampers in certain corridor penetrations.

Other options reference varying characteristics of duct construction or conditions under which smoke dampers would not be required, such as having no openings serving the corridor or being insulated. However, the specific mention of a minimum thickness threshold demonstrates a clear understanding of how physical properties of the duct system correlate with safety requirements pertaining to smoke containment in a fire scenario.