What is a potential consequence of not maintaining proper slope in vapor recovery piping?

Maintaining proper slope in vapor recovery piping is essential to ensure effective fluid drainage and proper gas flow. When the piping is not sloped correctly, one of the primary risks is the accumulation of liquid within the pipes. This liquid can come from various sources, such as condensate or liquid fuel vapors. If liquid accumulates, it can obstruct the flow of vapor that the system is designed to handle. This blockage can lead to a range of operational issues, including increased pressure in the system and possible leaks or failures.

Furthermore, liquid accumulation can undermine the efficiency of the vapor recovery system, as it interferes with the intended path and function of the vapor flow. In contrast, maintaining a proper slope allows gravity to assist in keeping the pipes clear of any liquid that could impede vapor movement, thereby optimizing the system's performance. Therefore, the risk of liquid accumulation is a direct and significant consequence of improper slope in vapor recovery piping, validating the correctness of the chosen answer.