What is the purpose of piping run sloping down to the tank?

The purpose of piping run sloping down to the tank is primarily to allow product to drain safely if air should enter the system. In the context of underground storage tanks (USTs), maintaining the integrity and flow of the stored product is crucial. A downward slope directs any liquid towards the tank, ensuring that, in the event of a leak or loss of pressure that allows air into the piping, the product can still efficiently flow back to the tank rather than becoming trapped or causing potential backups. This design minimizes the risks associated with product loss and helps maintain the system's overall functionality.

While considerations such as ease of installation, prevention of freezing, and pressure maintenance can be important in some scenarios, they do not capture the primary function of sloping piping toward the tank, which focuses on proper drainage and product recovery in the event of air ingress.