Patent ID: 8596290

Claim:
A pressure discharge valve for storage tanks comprising: a. valve body means having an outer or discharge end and a lower or entry end which is in contact with the storage tank, the valve body means having a through hole therein adapted to mate and communicate with a through hole in a wall of the storage tank; b. a first vent means which automatically provides a partial release of storage tank liquid at a first predetermined temperature lower than critical combustion and/or explosive temperatures of liquid in the storage tank, providing a visual signal and warning to firefighters of hazardous conditions that rupture of the storage tank or explosion of the liquid in the storage tank is imminent; c. a second vent means which automatically vents liquid in said storage tank through the hole in the valve body means when the liquids therein reach a predetermined critical temperature; d. a plug means adapted to be connected in threaded engagement with the valve body means, whereby to close the through hole therein until the temperature of fluids in the storage tank reaches a critical predetermined temperature; and e. a eutectic solder means disposed between the valve body means and first vent means, which changes upon reaching a predetermined critical temperature, thereby providing a lubrication effect between the valve body means and the first vent means; f. wherein a flange means is provided on the valve body means to aid in affixing the valve body means to the storage tank; g. wherein said first vent means further comprises a through vent hole in said plug means to facilitate a partial release of fluids from the storage tank to the atmosphere; h. wherein the vent hole in the first vent means is provided with a plug formed of a vent eutectic which seals the vent hole until a first predetermined temperature is reached when it becomes necessary to warn firefighters of hazardous temperatures in the storage tank; i. wherein said vent eutectic changes from a solid to a liquid over a predetermined temperature range, thereby melting the solid plug from the vent hole which results in a partial release of liquids from said first vent means; j. wherein the vent eutectic is selected from the group consisting of Bi 58 Pb 42 , In 52 Sn 48 , In 74 Cd 26 , and In 50 Sn 50 ; and k. wherein the valve body means has a round through hole which has a smaller diameter in contact with the storage tank than at the discharge end of the pressure valve, and a shoulder formed where the diameter of the through hole becomes larger.