Patent ID: 6848465

Claim:
A vent check valve comprising: (a) an outer housing including a first port and a second port, the first and second ports being arranged to permit gases to pass through and between the first and second ports in two opposed directions during dry conditions; (b) a first check valve in the housing, the first check valve being designed to substantially prevent a first elevated liquid inside the valve that has risen to or above a first trigger level from passing through the valve; (c) a second check valve in the housing, the second check valve being designed to substantially prevent a second elevated liquid external to the valve that has risen to or above a second trigger level from passing through the valve; (d) wherein the first and second check valves are substantially vertically aligned one above the other; and (e) wherein the outer housing includes at least one removable panel, the at least one panel being configured to permit access to at least one of the check valves in the valve housing when the panel is removed from the valve.