Which of the following is NOT a type of pipe that should be used in hood systems?

In the context of hood systems, the materials used for piping are crucial for safety and functionality. PVC (polyvinyl chloride) is a type of plastic that is not suitable for hood systems engaged in the collection and transport of flammable vapors or grease. This is primarily due to its lower temperature tolerance and flammability risk. Hood systems are often subject to high temperatures and potential fire hazards, which PVC is not designed to withstand.

On the other hand, black pipe, stainless steel, and chrome sleeving are materials that are commonly accepted for use in such systems. Black pipe is typically used for gas lines and has appropriate durability and heat resistance for duct applications. Stainless steel is employed for its corrosion resistance and ability to endure high temperatures, making it ideal for environments where grease and high heat are present. Chrome sleeving provides a protective and aesthetic finish to parts of hood systems, especially in commercial kitchens.

Therefore, the selection of appropriate piping materials is essential in ensuring that hood systems can effectively manage fire hazards while meeting safety standards.