Attwood Deck Fill f/Carbon Canister System - Straight Body Scalloped Chrome Cap [99DFCCSZ1S]Deck Fill for Carbon Canister System Straight Body & Scalloped Chrome Cap Pressure relief systems are designed with automatic diurnal emission control and overpressure relief safety valves built into the cap of the fill. The overpressure relief safety valves are engineered to release pressure above 1 psi. The high flow vacuum valves allow fresh air to enter the fuel tank to replace the fuel being consumed by the engine. Other components of a pressure