What type of piping, 12 inches in diameter, is used in the hydrant loop of a Type 3 system?

The correct answer indicates that stainless steel schedule 20s piping is used in the hydrant loop of a Type 3 system due to its specific properties that align with the requirements for such applications. Stainless steel is chosen for its superior resistance to corrosion, which is especially important in water and fuel systems where moisture can lead to degradation and leaks. The reduced wall thickness of schedule 20 piping compared to other schedules provides a balance between strength and weight, making it easier to install without compromising the structural integrity required for a hydrant loop.

Additionally, the use of stainless steel in this context ensures that the piping maintains its integrity over time, thus minimizing the need for maintenance and reducing long-term operational costs. While other materials and schedules may offer different attributes, they may not meet the same level of resistance to environmental factors or mechanical stress that is critical for a hydrant loop in a Type 3 system.