Pressure relief device

A pressure relief valve configured to vent a pressurized tank in the event of a fire, the pressure relief valve comprising:

• a body;
• a vent passage disposed through the body, the vent passage having a first end configured to be placed in fluid communication with an internal volume of the pressurized tank and a second end configured to be placed in fluid communication with the atmosphere and with a source of pressurized gas distinct from the pressurized tank, the vent passage at least partially enclosed by a vent passage wall;
• a plug moveably mounted in the vent passage, the plug comprising a seal end forming a seal with the vent passage wall and a control end spaced apart from the seal end,
• wherein the plug is moveable between a closed configuration and an open configuration, wherein the closed configuration seals the first end of the vent passage from the second end of the vent passage, and wherein the open configuration allows fluid communication between the first end of the vent passage and the second end of the vent passage;
• a latch having a blocking member disposed in contact with the control end of the plug in a first configuration, the latch being moveable such that the blocking member is out of contact with the control end of the plug in a second configuration to allow movement of the plug in the vent passage from the closed configuration to the open configuration;
• and
• a trigger actuation passage having a first end in fluid communication with the second end of the vent passage and a second end disposed opposite the first end;
• a trigger piston disposed in the trigger actuation passage, the trigger piston having an upstream end and a triggering end opposite the upstream end, wherein when the plug is in the closed configuration and the pressurized gas from the source of pressurized gas distinct from the pressurized tank is introduced into the trigger actuation passage through the second end of the vent passage, and pressure from the pressurized gas is applied to the upstream end of the trigger piston, the trigger piston is moved in the trigger actuation passage where by the triggering end causes the latch to be actuated from the first configuration to the second configuration.

A pressure relief valve configured to vent a pressurized tank in the event of a fire, the pressure relief valve comprising:

• a body;
• a vent passage at least partially enclosed by a vent passage wall disposed through the body, the vent passage having an upstream segment and a downstream segment;
• a plug moveably mounted in the vent passage, the plug comprising a seal end forming a seal with the vent passage wall and a control end spaced apart from the seal end;
• a trigger assembly comprising a shape memory alloy wire coupled to a lever arm at a first location of the lever arm, the lever arm being pivotably mounted within the body at a second location of the lever arm opposite the first location and comprising a first control surface disposed at a third location between the first location and the second location;
• a latch comprising an elongate body extending from a proximal end to a distal end along a longitudinal direction, the proximal end of the latch being rotatably mounted to the body, the distal end of the latch having a second control surface in contact with the first control surface of the lever arm,
• the latch further comprising a blocking member projecting laterally from the elongate body between the proximal end and the distal end, wherein the blocking member comprises a proximal facing contact portion configured to be disposed in contact with the control end of the plug in a first configuration, the latch being rotatable such that the contact portion of the blocking member is out of contact with the control end of the plug in a second configuration to allow movement of the plug in the vent passage;
• wherein the shape memory alloy wire is configured to shorten when exposed to a temperature above a threshold temperature to apply a load at the first location to overcome friction between the first control surface and the second control surface to pivot the lever arm and thereby to allow the latch to be in the second configuration to allow movement of the plug in the vent passage to cause the downstream segment of the vent passage to fluidly communicate with the upstream segment of the vent passage.