A fluid control device for use in a high pressure fluid system, the device including a device body with a cavity and a high pressure circuit, a plunger positioned for reciprocal movement in the cavity, and a leakage reduction cap mounted to the plunger for reducing fluid leakage flow. In one implementation, the leakage reduction cap includes a flexible portion positioned between the device body and the plunger, and defining an annular clearance gap between the leakage reduction cap and the device body. The flexible portion of the leakage reduction cap resiliently flexes radially outwardly in response to fluid pressure forces to reduce the annular clearance gap so as to minimize fluid leakage flow through the annular clearance gap.