Abstract: A method is disclosed for forming a thermally activated pressure relief valve which is designed to be attached to a pressure vessel. The valve contains a body having an inlet and an outlet in fluid communication with each other and an insert having a helical groove formed about its outer periphery. The method includes securing the insert in the outlet such that the helical groove cooperates with the body to form a helical passageway. A molten fusible material is then introduced into one end of the helical passageway. A force is exerted on the material to cause it to move through the helical passageway and displace any trapped air, gas or foreign matter which might be present therein. Once the material completely fills the passageway, it is allowed to cool and solidify. This method is advantageous in producing a safety relief valve which can operate at higher service pressures and temperatures over an extended period of time.

Abstract: A thermally activated valve is disclosed for attachment to a pressurized vessel such that substances contained therein can be released at a selected temperature value. The valve includes a body having an inlet and an outlet in fluid communication with each other. The inlet fluidly communicates with the interior of the pressurized vessel while the outlet is in communication with an area having a lower pressure value. Secured in the outlet is an insert having a stem. The stem has a helical groove formed about its outer periphery and has at least one small aperture which is in communication with the helical groove. The insert cooperates with the body to form a helical passageway therethrough. Positioned within the helical passageway is a material for normally blocking fluid flow therethrough which is fusible at a selected temperature to permit fluid flow therethrough.

Abstract: A combination thermal or pressure activated relief valve is disclosed. The valve includes a housing having an inlet and an outlet formed therein. The inlet is adapted to be attached to a pressure source while the outlet is in communication with an area having a lower pressure value than said pressure source. An insert is secured in the outlet and includes a stem having a first passage formed therethrough and a helical groove formed about its outer periphery. The groove cooperates with the housing to form a helical passageway between the inlet and the outlet. A fusible material is inserted into the helical passageway and normally blocks fluid flow therethrough and is fusible at a selected temperature to permit fluid flow therethrough. A second member is secured to the insert and has a passage formed therethrough which communicates with the first passage formed in the insert. A pressure responsive lamina is positioned across the passage for normally blocking fluid flow therethrough.