Vents the DEF tank during filling, defining the maximal DEF level and shutting off the filling process. It does this as well during the vehicle operation and parking. It prevents DEF leakage in all situations even in the event of roll over.
Prevents splash back of DEF through the filler pipe during the re-fueling process and shut off.
Can be assembled in-tank, on-tank or in-line subject to the DEF tank design and packaging constraints as well as to the DEF tank production process and the various requirements