Hazardous Materials Technician 3rd Edition Practice Test

Bottom discharge valves are the discharge feature on MC306 and DOT406 tanks. Placing the discharge connection at the bottom allows liquids to drain completely by gravity and be routed to a pump or hose with minimal residual product. This design is especially advantageous for viscous liquids and for achieving thorough unloading from a fixed, single discharge point. A top outlet would trap liquid in the lower portion of the tank; a side drain is not the standard configuration for these tanks, and a manual pump, while it may be used, is not an inherent, built‑in discharge feature.