Pressure regulating and relief valve assembly

摘要

A pressure regulating and relief valve assembly, such as an assembly positionable in a lower portion of a well casing. The valve assembly has a main relief valve assembly or back pressure regulator that is designed to open when the steam pressure exceeds a first predetermined value. A secondary relief valve assembly is provided to vent excess pressure to a space exterior of the valve assembly when the pressure exceeds a second predetermined value, the second value being higher than the first value. The valve assembly is positionable within a well casing at the bottom of a bore hole between a steam generator and a probe utilizing the steam generator. When the assembly is so positioned, excess pressure is vented to a space between the valve assembly and the inner surface of the encompassing well casing.