Fire responsive stem retention apparatus

A fire responsive stem retention apparatus for a non-rising stem valve having a bonnet with a bore therethrough, a backseat in the bonnet bore, a stem extending through the bonnet bore and above the bonnet, bearing means mounted on the stem above the bonnet, and a backseat flange on the stem below the bonnet backseat and spaced therefrom under ordinary operating temperatures, comprising:

• a hollow sleeve connected to the top of the bonnet around the bonnet bore and extending upwardly therefrom around the stem, said sleeve having an internal bore and an open upper end;
• inner cap means having a side wall portion closely fitted within the internal bore of said sleeve and connected thereto under such ordinary operating temperatures by a thin layer of fusible material between the outside surface of said side wall portion of said inner cap means and the wall of said internal bore of said sleeve, and a top portion connected to said side wall portion above and in engagement with the bearing means, partially closing said upper end of said sleeve, for providing an upper support for and preventing upward movement of the bearing means and stem under such ordinary operating temperatures and supporting the backseat flange below and spaced from the bonnet backseat;
• said thin layer of fusible material being melted when the valve is subjected to elevated temperatures, as in a fire, releasing the connection between said inner cap means and outer sleeve and removing the upper support for the bearing means and stem, thereby permitting the bearing means and stem to be moved upwardly by internal valve pressure until the backseat flange sealingly engages the bonnet backseat.

A fire responsive safety device having a normal operating state under normal environmental conditions and an emergency safe state under fire conditions, comprising:

• an outer member with a cylindrical inner surface;
• an inner member with a cylindrical outer surface, said inner member being received within said outer member;
• a thin layer of fusible material disposed between and normally bonding said outer surface of said inner member to said inner surface of said outer member in a position corresponding to the normal operating state;
• said outer member, when exposed to fire, conducting heat to said fusible material, causing it to melt, and permitting the safety device to assume the emergency safe state through relative motion of said inner and outer members;
• said inner member including means engageable with said outer member for preventing removal of said inner member from said outer member when said fusible material has been melted, said means engageable with said outer member including a slot through the side wall of said outer member, and an outwardly extending pin in the side wall of said inner member, riding in said slot.