Which type of duct is typically used for exhaust purposes in commercial kitchens?

Spiral duct is the preferred choice for exhaust purposes in commercial kitchens due to its structural integrity and efficient airflow characteristics. It is made from galvanized steel, which is durable and can withstand high temperatures, making it suitable for handling the heat and grease that can be present in kitchen exhaust systems. The smooth interior of spiral duct allows for reduced friction loss, promoting better airflow and reducing the energy required for ventilation.

Additionally, spiral ducts are typically installed in a way that minimizes the potential for grease buildup, which is crucial in preventing fire hazards in commercial kitchens. Their design also allows for easier maintenance and cleaning compared to other types of ductwork. This is important in a commercial kitchen environment, where compliance with health and safety standards is essential.

Flexible duct, while versatile, may not provide the same level of durability or resistance to high temperatures and grease. Thermal duct is typically used for insulation purposes rather than as a primary material for exhaust systems. Plastic duct is generally not suitable for exhaust applications in commercial kitchens due to its lower heat resistance and structural limitations. Thus, spiral duct emerges as the most appropriate choice for this specific application.