| 摘要 |
A fire protection sprinkler head which can reduce or substantially eliminate frame shadow effects that produce non-uniformity in spray pattern. The head is of the known type having a base with a throat through which fire retardant fluid flows and two or more frame arms which extend outwardly from the base and joint in an arch-form to support, in the path of fluid discharged from the throat, a central boss which deflects the fluid outwardly. It is found that a surprising reduction in frame shadow affects is obtained by constructing the frame arms to conform to the set of three essential parameters: (1) the portion of each frame arm in the region adjacent the boss is shaped and positioned to intercept the stream profile to a depth of at least one third the distance from the outside periphery to the center of the profile; (ii) the angle of the leading edge of each frame arm in this fluid intercept region, relative to the axis of flow, is less than about 25 degrees; and (iii) the cross-section of each frame arm in the fluid intercept region is slender, its length being two or more times the thickness of the frame arm, with the surfaces of each frame arm shaped to guide the fluid intercepted by that frame arm to flow into the region immediately downstream of its trailing edge.
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