What prevents fuel from entering a roof drain line?

Flange gaskets and asbestos ring packing are effective components for preventing fuel from entering a roof drain line due to their specific properties. Flange gaskets create a strong seal at the connections in the drainage system, ensuring that any potential leaks from the fuel lines are contained. Asbestos ring packing, while less commonly used today due to health concerns, has historically provided excellent sealing capabilities because of its durability and resistance to compressing under pressure.

In the context of roof drainage, it is essential to have materials that can withstand not only the physical and chemical properties of fuels but also environmental factors such as moisture and temperature variations. The combination of flange gaskets and either Teflon or asbestos packing forms a robust barrier that helps prevent fuel spillage into the drainage system, protecting the environment and maintaining system integrity.

The other options listed do not provide the same level of assurance or rely on materials that may not perform as effectively in this specific application. Therefore, the choice of flange gaskets and asbestos ring packing is the most suitable and historically grounded in industry practices for preventing fuel ingress into roof drains.