Which element is NOT part of the four primary functional elements of IPDS?

The four primary functional elements of the Integrated Petroleum Distribution System (IPDS) typically consist of various components that facilitate the logistics of petroleum supply. These elements include Tactical Petroleum Terminals, Pump Stations, and Pipeline Support Hardware, which work together to ensure the efficient transportation and storage of fuel.

While storage tanks do play a role in the overall petroleum distribution infrastructure, they are not classified as one of the primary functional elements of the IPDS. Instead, the focus is on the active elements that contribute directly to the movement and distribution of petroleum products. Therefore, identifying storage tanks as not part of the four primary functional elements aligns with the structure of how the IPDS is designed to operate, emphasizing the systems specifically used for distribution over mere storage capabilities.