Described is a check valve with a housing having an inlet side and an outlet side, a flow blocking valve element with centering protrusions, an inlet annular shoulder, an outlet annular shoulder, cylindrical valve element cavity with an aspect ratio such that the flow blocking valve element cannot be put in a position where it is jammed. The centering protrusions on the flow blocking valve element support it on the outlet annular shoulder and allow flow to pass between the central disc of the valve element and the larger diameter of the outlet orifice. When flow is attempted in the inhibited direction, the flow blocking valve element is pressed against the inlet annular shoulder, forming a seal and blocking the flow. The valve has the advantage of being inexpensive to manufacture and highly reliable.