What is the maximum allowable exposed surface temperature for a duct opening at 150 degrees F?

The maximum allowable exposed surface temperature for a duct opening at 150 degrees Fahrenheit is determined by safety standards to prevent burns and other hazards. In this context, an exposed surface temperature should be significantly lower than the duct's internal temperature to ensure it does not pose a risk to individuals who may come into contact with it.

Typically, safety guidelines suggest that temperatures above a certain threshold can be harmful. In many HVAC systems, the guideline often found is that the maximum allowable exposed surface temperature should not exceed 120 degrees Fahrenheit. This is based on research indicating that temperatures above this level can potentially cause discomfort or harm if touched.

Thus, the choice indicating 120 degrees Fahrenheit is the correct one as it aligns with safety practices in the HVAC industry aiming to protect users and ensure safe operation around heating components. Lower temperatures are typically favored to enhance safety and minimize the risk of burns.