Patent ID: 7591251

Claim:
A pressure valve assembly for a tank defining a storage cavity, the pressure valve assembly comprising: a housing having a valve seat; a biased closed, diaphragm-type, pressure relief valve having; a resilient diaphragm having a first side, an opposite second side, and a peripheral edge engaged sealably to the housing, a reference chamber defined at least in part by the housing and the first side of the diaphragm, a pressure chamber continuously communicating with the storage cavity, defined at least in part by the housing and the second side of the diaphragm and continuously communicating with the second side of the diaphragm, the valve seat continuously communicating with the pressure chamber, a valve head disposed in the pressure chamber and coupled to the diaphragm for movement relative to the valve seat to open and closed positions by the diaphragm; and a vent passage, defined at least in part by the housing, in communication between the valve seat and atmosphere, and in communication with the valve head at the valve seat for relieving super-atmospheric pressure from the storage cavity to atmosphere at or above a threshold super-atmospheric pressure in the storage cavity; and a separate relief valve carried by the housing and communicating with the pressure chamber and the atmosphere to open to relieve sub-atmospheric pressure in the storage cavity and to be urged closed by superatmospheric pressure in the storage cavity.