in the form of the invention chosen for illustration herein and as best seen in fig1 and 3 of the drawings , the sprinkler comprises an apertured body member 10 , the lower portion of which is externally threaded as at 11 so that it can be turned into a pipe fitting in a sprinkler system . the apertured body member 10 defines a fluid delivery passage 12 as seen in fig3 and 5 of the drawings and the discharge end thereof is normally closed by a closure cap 13 and gasket 14 . a frame formed of oppositely disposed spaced arms 15 is integrally formed with the body member 10 and the outer end of the arms 15 are joined as at 16 to form a passageway 17 in which a stakable compression screw 18 is positioned . a deflector 19 is secured to the outer end of the compression screw 18 . the compression screw 18 extends inwardly of the junction 16 of the arms 15 and it lies on the axial center line of the fluid delivery passageway 12 of the sprinkler . the inner end of the screw 18 is pointed for registry with a depression in a substantially horizontal portion 20 of an inverted generally l - shaped lever 21 . a straight substantially vertically positioned strut 22 is positioned with one of its ends in a depression in the closure cap 13 and its opposite end against the inner surface of the substantially horizontal portion 20 of the lever 21 and between a pair of spaced projections thereon . the strut 22 is positioned substantially on the axial center line of said fluid delivery passageway 12 . the strut 22 has a pair of oppositely disposed sidewardly extending apertured arms 23 formed integrally therewith and inwardly of its upper and lower ends and the substantially vertical portion of the lever 21 extends into the area between the arms 23 . by referring now to fig1 and 4 of the drawings , it will be seen that a fusible element including a tubular body 24 is positioned between the apertured arms 23 so that a pair of spheres 25 positioned partially within the ends of the tubular body 24 are also partially engaged in oppositely disposed apertures 26 in the outer portions of the arms 23 . a pair of discs 27 are located one on either side of a pellet of fusible material 28 with the discs 27 engaging the innermost surfaces of the spheres 25 . the pellet 28 is formed of eutectic fusible alloy as known in the art , which may have various known melting temperatures as desired . by referring to fig4 of the drawings in particular it will be observed that the outermost ends of the tubular body 24 are crimped slightly so as to cage the spheres 25 therein which is useful during assembly of the sprinkler as disclosed herein . the outer surfaces of the opposite ends of the tubular body 24 are tapered slightly . by referring now to fig5 of the drawings , a sectional elevation similar to fig3 may be seen illustrating the sprinkler of the invention as in opening responsive to the fusible element 24 reaching the predetermined desired temperature , for example 165 ° f . in fig5 of the drawings it will be seen that the fluid pressure normally present in the fluid delivery passageway 12 has been released by the action of the fusible element which permits the discs 27 and the spheres 25 to move inwardly of the tubular body 24 so that the fusible element can move outwardly of the openings 26 in the apertured arms 23 of the strut 22 responsive to the pressure urging such action as occasioned by the tension on the substantially horizontal portion 20 of the lever 21 and assisted by the pressure of the fluid in the fluid delivery passageway 12 . the gasket 14 , cap 13 , strut 22 and lever 21 as well as the fusible element in the tubular body 24 all move away from the sprinkler and permit the fluid discharged through the fluid passageway 12 to strike the deflector 19 and be directed in a desired pattern . it will be seen that the arrangement of the fusible element in its horizontally disposed tubular body 24 normally positioned between the apertures 26 in the outer portions of the apertured arms 23 of the strut 22 of the device with only limited contact therewith enables the fusible material of the pellet 28 to respond quickly to the air temperatures exteriorly thereof so that the sprinkler responds more rapidly upon being subjected to the predetermined operating temperature than has heretofore been the case . it will be seen that upon fusing of the material of the pellet 28 , either or both of the spheres 25 and the discs 27 may move toward one another and such movement of either sphere 25 relative to the apertured arms 23 results in the fast opening of the sprinkler . it will thus be seen that a sprinkler has been disclosed which is relatively simple in construction and assembly and which may be formed of a relatively small size and retain complete effectiveness . for example a typical sprinkler formed in accordance with this invention has an overall height of two and three - eighths inches and an overall width at its widest part of only one and three - eights inches and it locates its heat sensitive fusible element in a manner that substantially isolates it with respect to the remainder of the sprinkler so as to assure rapid operation at an indicated air temperature .
a sprinkler for use in a fire extinguishing system includes an apertured body member , a closure cap , a frame supporting a deflector , a strut holding the closure cap and a lever bearing against said strut and releasably retained by a transversely disposed fusible element engaging spaced apertured arms on said strut .