Abstract: The invention is an improved valve having a valve body, a valve stem having a valve plug portion and a valve stem portion, and a valve guide having an aperture in which the valve stem portion is received for reciprocal movement of the valve stem longitudinally inside the valve body. A valve seat is supported in the valve body and includes a pair of spaced apart circular valve seat surfaces that each sealingly engage a separate surface of the valve plug portion;. A spring biases the valve plug portion into sealing engagement with the valve seat. The valve seat has a pair of sealing surfaces that are brought in sealing engagement with distinct surface portions of the valve stem to provide improved and redundant sealing function. The valve has improved longevity and reliability.