Abstract: The invention is a fluid discharge valve wherein the force necessary to mtain the valve in a closed position in the absence of fluid pressure is kept at a very nominal pressure. The fluid discharge valve further provides for the force on the valve body to increase proportional to the pressure up to a pre-determined value. At this pre-determined value, means are provided to open the valve and thereby allow fluid to pass. The invention provides for a discharge valve which maintains its initial calibration, as well as avoids the valve body and valve member to be exposed to a high closing force in the absence of fluid pressure. Further, means are provided to allow for selecting the pre-determined value.