ICC Commercial Mechanical Practice Exam

Which of the following is not a required feature for the construction of exhaust ducts for clothes dryers?

1. Metal construction

2. Smooth interior finish

3. Minimum nominal size

4. Plastic material

The correct answer is: Plastic material

The construction of exhaust ducts for clothes dryers is regulated to ensure safety and efficiency. One of the key elements of these regulations is that the ducts must be made from materials that can withstand high temperatures and resist the potential risks associated with fire hazards. Therefore, metal construction is mandated as it provides durability and fire resistance, and a smooth interior finish is necessary to minimize the accumulation of lint and enhance airflow. A minimum nominal size is also a requirement to ensure that the duct can effectively accommodate the volume of exhaust produced by the dryer, promoting proper ventilation. Plastic material, on the other hand, is not suitable for dryer exhaust ducts due to its lower heat resistance and susceptibility to melting or deforming under high temperatures. As such, it does not align with the necessary safety standards for this application, making it the correct choice as the feature that is not required for the construction of exhaust ducts for clothes dryers.