초록 ▼

A valve operator for a normally open valve is maintained in a cocked, ready to close mode by an arrangement which includes a radially contracted, self-expansible split retainer ring backed by a body of fusible material. Should the vicinity of the associated valve be subjected to the heat of a fire,

A valve operator for a normally open valve is maintained in a cocked, ready to close mode by an arrangement which includes a radially contracted, self-expansible split retainer ring backed by a body of fusible material. Should the vicinity of the associated valve be subjected to the heat of a fire, the fusible body will melt out of blocking relation, permitting the split ring to expand free of the operator stem. A cocked spring recovers, axially moving the stem both to shut the valve and to engage a metal-to-metal back seat between the valve stem and valve bonnet. The latter event ensures against leakage even if the fire or wear has ruined the integrity of the usual valve stem packing. The valve operator is further provided with a manual override which permits the valve to be closed and opened, e.g. using a remotely actuated pneumatic operator even while the body of fusible material remains intact and in place.

대표청구항 ▼

A heat responsive back seat arrangement for a valve operator having an override, comprising: valve housing means including valve bonnet means having a bore; a reciprocate-in-one-sense-to-close, reciprocate-in-opposite-sense-to-open valve body having a rising valve stem connected therewith; the valve

A heat responsive back seat arrangement for a valve operator having an override, comprising: valve housing means including valve bonnet means having a bore; a reciprocate-in-one-sense-to-close, reciprocate-in-opposite-sense-to-open valve body having a rising valve stem connected therewith; the valve body being enclosed within the valve housing means, with the valve stem passing out through said valve bonnet means bore; an annular body of axially compressively loaded valve stem packing installed to form a seal between the valve bonnet means and the valve stem, yet permit axial reciprocating movement of the valve stem relative to the valve housing means; complementary, circumferentially extending back seat, annular sealing surface bearing shoulder means on each of said valve stem and said valve bonnet means in said bore of the latter, the two respective annular sealing surfaces being disposed on their respective parts to form an extensive, surface-to-surface circumferential seal between the valve bonnet means and the valve stem only when said valve stem is reciprocated to one resultingly-defined extreme of axial movement relative to said valve housing means; a valve operator located relatively exteriorly of said valve housing compared to said valve body by being separable therefrom by said back seat; said valve operator including normally-cocked force-storage means effectively interposed between said valve stem and said valve housing means, to when released, axially move said valve stem to said one extreme thus making said circumferential seal of said back seat, the valve operator including means for selectively resiliently axially loading and releasing said force-storage means; lock-out means normally effectively interposed between said valve stem and said valve housing means, normally locking said valve stem in a resultingly-defined axially opposite extreme thereof, in which said annular sealing surfaces are axially spaced from one another and are not in circumferential sealing engagement, and in which said force-storage means is resultingly normally cocked; the lock-out means including a thermally fusible element effectively interposed between said valve stem and said valve housing means which, in the absence of subjection to a preselected abnormally high temperature level remains an effective mechanical bridge therebetween, but which, when subjected to said preselected abnormally high temperature level softens and becomes ineffective as a mechanical bridge, thereby releasing said normally-cocked force-storage means, to axially move said valve stem to said one extreme thus making said circumferential seal of said back seat; the lock-out means further including an override means, comprising: joint means dividing said valve stem into two coaxially aligned, telescopically related portions, being a main stem portion and a lock-out stem portion which are normally fully telescoped into abutting relation, the valve body being mounted to said main step portion; and means for reversibly axially partially withdrawing the lock-out stem portion relative to the main stem portion, so as to enable the main stem portion to move axially from said opposite extreme toward said one extreme and back to said opposite extreme, by use of said means for selectively resiliently axially loading and releasing said force-storage means, while said lock-out stem portion is axially partially withdrawn relative to said main stem portion even while said thermally fusible element remains interposed as a mechanical bridge between said valve stem and said valve housing; said lock-out means further including: a band of screw threading on said lock-out stem portion; a drive bushing threadably mounted on said band; a radially outwardly opening notch in said drive bushing; a locking dog means normally forced part-way into said notch; force-storage means associated with said locking dog means, and tending to withdraw said locking dog means from said notch; and said thermally fusible element being constituted by a block of heat-fusible material normally effectively interposed between said locking dog means and said valve housing means, so that when said block softens due to being heated and tends to lose interposition effectiveness, said force-storage means associated with said locking dog means releases force stored therein and said locking dog means withdraws from said notch, freeing said valve stem to axially move toward said axially opposite extreme.