Fluid sprinkling – spraying – and diffusing – Slow diffusers – Gravity flow of liquid from supply holder
Reexamination Certificate
2001-05-22
2004-04-27
Hwu, Davis (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Slow diffusers
Gravity flow of liquid from supply holder
C239S038000, C239S039000, C239S040000, C239S041000
Reexamination Certificate
active
06726119
ABSTRACT:
TECHNICAL FIELD
The invention relates to water spray sprinklers and nozzles for fire protection service, and, in particular, to those nozzles in which a single stream of water is discharged and impacts or impinges against a downstream element as a means of deflecting, spreading or diffusing the discharge stream into a spray pattern consisting of individual droplets.
BACKGROUND
Water sprays consisting of relatively small or fine water droplets, commonly referred to as “water mist”, have been shown to be among the most efficient fire extinguishing media currently available. Small water droplets suspended in the atmosphere can be forcibly injected or entrained through the convective currents, into the combustion region of a fire, where they quickly evaporate. The evaporation of these droplets has an impact upon the combustion process by absorbing some quantity of the energy output of the fire, and by displacing gaseous oxidizing agents. At some critical point, when the fire is no longer capable of self-sustained combustion, it is extinguished. It has been shown that droplets of less than 50 microns in size are extremely efficient fire extinguishing agents. As droplet size increases, the efficiency of the fire extinguishing media, typically water, decreases, although it has been demonstrated that water mist with the majority of the droplets between 20 and 250 microns in size can be highly effective and efficient fire extinguishing agents, particularly when delivered in a componentized spray pattern. Fischer U.S. Pat. No. 5,839,667 teaches that it can be desirable to selectively provide areas of higher water discharge per unit area, greater droplet size, and/or greater droplet momentum. It has also been shown that different expected fire scenarios may require different spray pattern characteristics, if the effectiveness of fixed fire fighting system is to be maximized.
The main types of water mist nozzles for fire protection include diffuser impingement nozzles, pressure jet nozzles, and gas atomizing nozzles. Diffuser impingement nozzles operate by impacting a coherent water stream against a diffuser. The diffuser breaks the stream into a predetermined distribution of mist. Diffuser impingement-type water mist nozzles are described in Fischer U.S. Pat. No. 5,392,993 and in Fischer U.S. Pat. No. 5,505,383. Pressure jet nozzles function by discharging high velocity water streams through small orifices with an internal shape, e.g., a scroll-type arrangement is typical, designed to break up the water stream. A pressure jet type water mist nozzle is described in Sundholm U.S. Pat. No. 5,513,708. Gas-atomizing water mist nozzles operate by mixing compressed gas with water in a mixing chamber at the nozzle discharge orifice. A gas atomizing water mist nozzle is described in Loepsinger U.S. Pat. No. 2,361,144.
The spray pattern characteristics produced by existing diffuser elements utilized in impingement-type water mist nozzles fall into two distinct categories. The first category is a relatively uniformly filled, umbrella-shaped spray pattern extending from the discharge nozzle. The second category is a largely hollow cone, with the spray pattern forming a uniform or non-uniform shell of spray. Fischer U.S. Pat. No. 5,829,684 describes a nozzle producing a combination of these two fundamental types, with a uniform, umbrella-shaped shell superimposed over a relatively uniformly filled inner cone.
SUMMARY
According to one aspect of the invention, an upright-type fire protection spray mist nozzle comprises a base defining an orifice, with an orifice axis, through which fire-retardant fluid can flow, an inlet section having an upstream end and defining a conduit for flow of fire-retardant fluid along the orifice axis and leading to an upstream end of the orifice, and a diffuser element positioned coaxially downstream of the orifice, the diffuser element defining an impingement surface that is at least substantially imperforate in the axial direction and positioned for impingement by a stream of fire-retardant fluid flowing from the orifice in a stream direction along the orifice axis. The impingement surface comprises a central conical shape surface region extending generally toward the orifice, with an apex portion disposed along the orifice axis, a peripheral edge disposed generally radially outward from the conical shape surface region and defining a face plane, and a concave, substantially toroidal surface region generally between the conical shape surface region and the peripheral edge.
Preferred embodiments of this aspect of the invention may include one or more of the following additional features. The apex and the peripheral edge are disposed in a plane generally perpendicular to the orifice axis. Preferably, at least a portion of the toroidal surface region is recessed downstream from the plane of the apex and the peripheral edge, relative to the orifice. More preferably, the toroidal surface region is recessed downstream from the plane of the apex and the peripheral edge, relative to the orifice. The stream of fire retardant fluid flowing from the orifice to impinge upon the impingement surface is substantially steady and coherent. The concave, substantially toroidal surface region has a shape formed by rotation of an arcuate surface comprised of at least three relatively smoothly blended arcs, and preferably at least five relatively smoothly blended arcs, about a line defined by the orifice axis passing through the apex. The impingement surface defines at least one surface discontinuity in a region of the peripheral edge for redirecting a portion of the flow of fire retardant fluid along the impingement surface. Preferably, the impingement surface defines a set of surface discontinuities spaced circumferentially about the orifice axis in the region of the peripheral edge for redirecting a portion of the flow of fire retardant fluid along the impingement surface. The set of surface discontinuities generally has the form of a set of notches in the impingement surface. Preferably, the set of notches defines a set of surface regions extending along and outwards from a plane generally tangent to a base region of the concave surface and lying generally perpendicular to the orifice axis, towards the region of the peripheral edge. The set of surface discontinuities comprises a set of at least about eight notches, preferably a set of at least about 16 notches, more preferably a set of at least about 32 notches, and still more preferably a set of at least about 48 notches, in the impingement surface. The stream of fire retardant fluid flowing from the orifice and intersecting the impingement surface has a stream diameter measured as the stream is about to pass through the face plane, and a ratio of the diameter of a region of the concave surface lying generally tangent to a plane that is generally perpendicular to the orifice axis and the stream diameter is greater than or equal to about 2, preferably greater than or equal to about 3, and more preferably greater than or equal to about 4. The peripheral edge has an inner edge diameter measured in the face plane and the stream has a stream diameter measured as the stream is about to pass through the face plane, and a ratio of the inner edge diameter to the stream diameter is at least about 3, preferably at least about 5.5, more preferably at least about 8, and still more preferably of the order of about 20. Preferably, the set of surface discontinuities divides the flow into multiple segments at the region of the peripheral edge with little loss of energy. The upright-type fire protection spray mist nozzle may be in the form of an open nozzle for use in deluge-type fire protection systems, or may be in the form of an automatically-operating nozzle comprising, in a standby condition, a releasable orifice seal secured in position by a thermally-responsive element, or may be in the form of a device remotely actuatable, e.g., in response to a fire condition determined by a separate fire detector.
According to another aspect of the invention, an
Fischer Michael A.
LeBlanc David J.
French, Esq. Timothy A.
Grinnell Corporation
Hwu Davis
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