Which component must be sloped toward the tank for vapor and fuel lines?

The requirement for vapor and fuel lines to be sloped toward the tank is essential to ensure proper drainage and to prevent the accumulation of liquid that could interfere with the function and safety of the underground storage tank system.

When considering the components involved:

• Venting is necessary for maintaining proper pressure within the tank, and if these lines are not properly sloped, they could trap vapors and create pressure or vacuum problems that could lead to operational failures or safety hazards.

• Gravity fill lines, designed to allow fuel to flow into the tank, need to be at a slope that facilitates the smooth, unimpeded flow of fuel. If these lines are not sloped toward the tank, it could result in fuel flowing back or pooling, which is not ideal for both functionality and safety.

• Suction supply lines are critical for drawing fuel from the tank to the dispensing equipment. A proper slope ensures that these lines remain filled with product and do not allow air to enter, which would disrupt the flow and potentially cause the system to fail.

Therefore, each of these components must be sloped toward the tank to ensure the overall efficiency, performance, and safety of the underground storage tank system. This is why the correct answer encompasses all the components listed, reflecting