A double port regulator assembly includes a first fluid port and a second fluid port. A fixed valve seat assembly is disposed proximate the first fluid port and a floating valve seat assembly is disposed proximate the second fluid port. A first valve plug cooperates with the fixed valve seat assembly to open and close the first fluid port and a second valve lug cooperates with the floating valve seat assembly to open and close the second fluid port. The floating valve seat assembly includes a floating valve seat that is movable with respect to the fixed valve seat.

A pressure relief valve (PRV) assembly may include a housing having an opening therein, an interior cavity, a passageway extending between the opening and the interior cavity, and a flange extending within the passageway adjacent the opening. The PRV assembly may also include a first stage valve carried within the interior cavity, and a second stage valve fluidly coupled in series with the first stage valve. The second stage valve may include an enlarged head carried within the opening and a shaft extending from the enlarged head through the passageway to the interior cavity. The shaft may have a proximal end coupled to the enlarged head and an opposing enlarged distal end adjacent the interior cavity. A biasing member may be between the enlarged distal end and the flange. The biasing member may be configured to bias the first and second stage valves to a closed position.