A restriction valve in accordance with an embodiment of the present invention includes a valve body adapted to be positioned at an inlet of the sprinkler, wherein the valve body includes a central opening through which water flows into the sprinkler, a rib extending downwardly from the valve body at a location beyond the margin of the central opening, a valve member configured to cooperate with the central opening to open and close the valve, wherein the valve member includes a valve stem extending downwardly from the valve member, and positioned and configured to be movably supported in a guide ring formed at a lower end of the rib, wherein the valve stem is movable vertically to move the valve member to its open and closed positions and a resilient member biasing the valve stem such that the valve member remains in an open position until water pressure pushing against the valve member reaches a predetermined level to move the valve member into the closed position to restrict the flow of water into the sprinkler