Fire-responsive Sprinkler Head

Abstract

A fire extinguishing sprinkler head for use with a wide range of extinguishants, such as water and hydrolized ablative gel, which has an expellable plug retained in a discharge opening in the sprinkler head by fire-responsive release means. Upon actuation of the release means, the plug is expelled from the sprinkler head by the pressure of the extinguishant to clear the discharge opening of obstacles which could affect the spray pattern of the extinguishant emitted from the sprinkler head. The plug is released at a predetermined inlet head pressure so that the sprinkler head will not provide the extinguishant to the fire at a pressure which will materially affect the spray pattern from the sprinkler head or adversely influence the spray pattern of other sprinkler heads in the system. The sprinkler head also includes means for modulating the flow of extinguishant in response to the inlet pressure of the extinguishant to retain a predetermined extinguishant spray pattern and to maintain the extinguishant supply pressure to the system at a higher level.

Description

BACKGROUND OF THE INVENTION

This invention relates to fire-responsive sprinkler heads. More particularly, this invention relates to a sprinkler head which includes an expellable plug which is discharged from the sprinkler head in the event of a fire. Still more particularly, the sprinkler head according to the invention operates only when the inlet pressure is above a predetermined minimum and also includes means for varying the effective area of the nozzle orifice as a function of the inlet pressure to maintain the system inlet pressure at an effective level and to preserve the spray characteristic of the extinguishant from the sprinkler head.

Fire protection systems are known to the art which provide a supply of extinguishant under pressure through a suitable conduit network to a plurality of fire-responsive sprinkler heads. Such systems are intended to retain the extinguishant under pressure for ready release by actuation of a fire-responsive element such as a thermally actuated fusible member. It is an overall problem in the design of such systems and in designing fire-responsive sprinkler heads to provide for effective operation of the system under a reduced extinguishant supply pressure. For example, while a single operative sprinkler head will receive nearly full operating pressure, successive actuation of additional sprinkler heads will cause the inlet pressure to the sprinkler heads to decay, often resulting in an unacceptable operation of the system.

The spray characteristic of the extinguishant from the actuated sprinkler head is chosen so that the extinguishant survives the flow path from the sprinkler head to the protected area and so that the spray provides a uniform coverage of the area. Thus, spray angles, extinguishant droplet trajectories, extinguishant particle size distribution and particle velocity all play an important part in ascertaining the effectiveness of the system and are generally variable as a function of the inlet pressure.

Moreover, in a multiple sprinkler head system, the spray patterns are selected to provide optimum coverage of protected areas. In the event of a fire, the convective effect of a combustion in the protected area will distort the spray and thus reduce the extinguishing efficiency of the system. Under these conditions, a drop in extinguishant pressure may affect the performance of the system to such an extent that it is preferable to leave a sprinkler head unopened rather than further reduce the available extinguishant pressure. Thus, it is a problem in the art to provide a fire-responsive sprinkler head which responds positively when actuated, but which will remain non-responsive when the extinguishant pressure falls below a predetermined minimum.

The drop in the inlet pressure of the system also causes a deterioration in the effectiveness of the sprinkler heads which have already opened in response to the fire. Inasmuch as such opened heads are most likely in the region of concentrated combustion, it is desirable to maintain the spray characteristics of the actuated sprinkler head although the exit flow rate of extinguishant has been reduced by the opening of additional sprinkler heads. Thus, there is a need in this art for a sprinkler head which can maintain a flow of extinguishant to its assigned area through a wide range of line pressures supplying that head.

The advent of fire protection systems which utilize extinguishants other than water imposes still another design constraint on the sprinkler head. It is, of course, desirable to provide a sprinkler head which may be used with a wide range of extinguishants to facilitate its use as a replacement for the heads of existing systems, or as a part of a new installation which uses an extinguishant different from water, such as fully hydrolized ablative gel. A method of fire protection using a gelling agent in the form of a water swellable polymer which is injected into a flowing stream of water supplying the sprinkler heads of a fixed extinguishing system upon actuation thereof is disclosed in a copending application, Ser. No. 766,475 filed Oct. 10, 1968 by William L. Livingston and Russell W. Pierce, and assigned to the assignee of the present invention.

Thus, it is a principal object to provide a positive acting fire-responsive sprinkler head for use in a fixed sprinkler system.

It is an additional object of the invention to provide a sprinkler head having a plug member which is expelled from the sprinkler head when fire responsive means are actuated.

It is a further object of this invention to provide a sprinkler head in which fire-responsive means are provided to retain an expellable member in the discharge opening of the sprinkler head and, when actuated, permit the member to be expelled from the sprinkler head by the pressure of the extinguishant.

It is still another object of this invention to provide a sprinkler head which will release an expellable plug only when the extinguishant pressure is above a predetermined minimum.

It is still a further object of this invention to provide a sprinkler head having means to modulate the flow of extinguishant in response to the inlet pressure.

These and additional objects will become apparent from the detailed description which follows when perused in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

A sprinkler head which overcomes the problems in the art, as discussed above, and which achieves the stated objects, comprises a body which includes an inlet portion for receiving a continuous supply of fire extinguishant and a discharge portion defining a discharge opening. An expellable member is disposed within the body for sealing the discharge opening when the sprinkler head is in its quiescent state. Fire-responsive means, including a spring-biased trigger member and a fire-sensing member are provided for securing the expellable member within the body of the sprinkler head. When the fire-sensing member is actuated, the spring-biased trigger rod releases the expellable member so that the expellable member may be ejected through the discharge opening of the sprinkler head. An O-ring seal is provided between the expellable member and the discharge opening and may be selected so that the member will not be expelled unless the extinguishant pressure exceeds a predetermined minimum. In a preferred embodiment, the sprinkler head also includes pressure-responsive means for varying the effective area of the nozzle orifice in the sprinkler head in response to the extinguishant supply pressure to maintain the spray characteristics of the extinguishant over a wide range of pressures and to maintain the inlet pressure of the extinguishant at an effective level. The pressure-responsive means include a fixed member secured to a moveable plug by a pair of accordian members to define a cavity containing a predetermined quantity of a compressible material. Spinner vanes are located in the body of the sprinkler head to impart a rotational characteristic to the flow of the extinguishant through the sprinkler head. The discharge opening may be provided with means for producing non-circular spray pattern. For example, a plurality of radially-emanating generally V-shaped notches communicating with the discharge opening and the exterior of the sprinkler head will produce a generally rectangular or square spray pattern. In an alternative embodiment which produces a non-circular spray pattern, a conical discharge passage is provided at the outlet of the sprinkler head which terminates at a surface formed by the intersection of a right parallelepiped having an axis parallel to the axis of the cone and in which the plane cross section of the parallelepiped defines a square or a rectangle.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a view, substantially in cross-section, of the sprinkler head according to the invention;

FIG. 2 is a view taken along line 2--2 in FIG. 1;

FIG. 3 is a view taken along line 3--3 of FIG. 1;

FIG. 4 is a cross-sectional view of an alternate discharge arrangement for producing a non-circular spray pattern; and

FIG. 5 is a view taken along line 5--5 of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, a sprinkler head according to the invention is designated generally at 10 and comprises a body 11 which includes an inlet portion 12, an intermediate portion 13, and a discharge portion 14.

The inlet portion 12 of the sprinkler head 10 includes threads 16 for attachment to an outlet conduit (not shown) which forms a part of a multi-head sprinkler system which has a plurality of sprinkler heads located in a predetermined array with respect to an area to be protected in the event of a fire. The inlet portion 12 defines an inlet area which is relatively large compared to the area defined by the discharge portion 13 to minimize pressure losses at the inlet and to provide a potentially large supply of extinguishant to the discharge portion 13 of the sprinkler head 10 when the sprinkler head is actuated. Since fixed fire extinguishing systems, in general, remain inactive for long periods of time, the inlet area also permits the free passage of solids which may have accumulated in the system during the period of its inactivity.

The size of the inlet portion 12 is determined by a number of design criteria which include such factors as the volumetric availability of the extinguishant to the overall system, the static pressure of the extinguishant, the number of heads in the system, the desired flow rate from the sprinkler head at that particular position in the system, the characteristics of the extinguishant supply system, and the like. Moreover, the overall design characteristics of the nozzle 10, including the inlet portion 12, are selected to allow the nozzle to be used with a wide range of extinguishants encompassing for example, both water and fully hydrolized ablative gel.

A plurality of spinner vanes 17 are secured, as by integral casting or welding, to the interior wall of the intermediate portion 13 of the sprinkler head 10. The vanes 17 cause the extinguishant to flow in a spiral streamline through the sprinkler head and thus provide a first control over the flow characteristics of the extinguishant as it exudes from the discharge nozzle. Since the vanes 17 are often necessary to control the flow of extinguishant from the relatively large inlet opening discussed above, the number of vanes and their physical characteristics are also determined by the factors discussed with respect to the determination of the area of the inlet opening. For example, a relatively long spiral surface 18, acting on the extinguishant through a large arc, for example 180.degree., will impart a greater rotational characteristic to the flow of extinguishant than will a shorter spiral path acting through a lesser arc.

In its quiescent or unactuated state, the sprinkler head 10 includes a rod 20 secured to an expellable plug designated generally at 21 which forms a watertight seal with the discharge opening 22 defined by the discharge portion 14 of the sprinkler head 10. In the embodiment depicted, the plug 21 includes an annular member 24 having a diameter nearly equal to the diameter of the discharge opening 22. An annular groove 25 is located in member 24 to accommodate a sealing member 26. It should be noted that the plug 21 may either be a separate member secured to the rod, as shown, or may form an integral part of the rod.

Means, designated generally at 28 and responsive to the presence of a fire, such as by thermal actuation, are provided for securing the rod 20 within the sprinkler head 10 during its rest state. A trigger rod 30 includes a protruding portion 31 located in an opening 32 defined near the distal end of the rod 20. When the trigger rod 30 is connected to the member 20 as shown, or is secured to rod 20 by an equivalent connection, it acts as an effective means for retaining rod 20 and plug 24 within the sprinkler head.

A retaining member 35, best seen in FIG. 2, defining an axial opening 36 for receiving the distal end 33 of rod 20 and a lateral opening 37 for accommodating the protruding portion 31 of the trigger rod 30 is provided to impart structural integrity to the connection between the rod 20 and the trigger rod 30 without greatly affecting the flow characteristics of the extinguishant through the sprinkler head. The retaining member 35 may be integrally cast within the sprinkler head 10 or may be formed separately and secured to the interior of the sprinkler head 10 by means known to the art, such as by welding a portion thereof to the spinner vanes 17, or by the judicious use of fasteners.

A threaded nipple member 40 defining an opening 41 is engaged with a mating threaded opening 42 located in a wall portion 43 positioned at the transition between the inlet end portion 12 and the intermediate portion 13 of the sprinkler head 10. The wall portion 43 may be provided with an increased wall thickness as shown to provide additional strength if desired. The opening 42 is sized to accommodate the trigger rod 30 in its quiescent state and to permit axial movement of the trigger rod 30 therethrough in the event of a fire, as will be discussed.

A coupling member 45 defining an interior cavity 46, a first threaded opening 47 and a second threaded opening 48 is threadedly engaged with nipple 40. Preferably, openings 41, 47 and 48 are disposed about a common axis to permit free axial travel of the trigger rod 30 when the sprinkler head is actuated.

A first annular member 50, such as a washer, is provided about an intermediate portion of the trigger rod 30 and rests against a surface 52 defined by the anterior end of nipple 40. A spring 54, also located about an intermediate portion of the trigger rod 30 is contained within the cavity 46 of the coupling member 45 and includes a first end 55 abutting the first annular member 50 and a second end 56 abutting a second annular member 57, such as a washer, located about the trigger rod 30.

A third annular member 59 provides a shoulder for retaining the trigger rod in its illustrated position in position in the absence of a fire and to retain the spring 54 in a compressed, or biased state. The annular member 59 may constitute an integral part of the trigger rod 30, or may be eliminated if the head portion 60 of the trigger rod 30 has a diameter which is sufficiently great to provide a shoulder against which the annular member 57 may rest.

A conventional fire detector, designated generally at 62, comprises a housing 63 secured to a base 64 having a threaded portion 65 in a threaded arrangement with the mating threads in the opening 48 of the coupling member 45. The base 64 and the portion of housing 63 adjacent thereto together define an opening 67 for receiving the head portion 60 of the trigger rod 30.

It is an advantage of the system to use conventional fire detectors for either water sprinkler systems or ablative gel sprinkler systems since such detectors are presently approved by fire protection agencies, insurance companies, trade associations and other interested authorities. In this manner the accumulated experience and the low cost of the conventional fire detectors may be used to great benefit. However, this system is not confined to actuation by either the illustrated thermally-actuated device or by known fire detection elements since the fire-preventative characteristics of ablative gel systems may dictate certain modifications in the opening characteristics of the sensing element, in response to its controlling parameter, e.g. heat, flame, smoke and the like, to utilize the benefits of the ablative gel systems to full advantage. For example, the performance of ablative water systems may permit later actuation of the fire detector to permit alternate forms of fire protection to be used first, while yet providing an improved margin of safety. Thus, it may be possible to avoid actuation of the system by nuisance and small fire operations without compromising the safety of the premises.

A fire-responsive element designated generally at 69, comprises a first fusible portion 70 and a second fusible portion 71 mounted in the housing 63 between a first supporting member 72 and a second supporting member 73. The element 69 is designed to forsake its structural rigidity at a predetermined temperature, thus permitting the head portion 60 of the trigger rod 30 to extend axially under the influence of the spring 54 thereby freeing the rod 20 from its restraining influence on the trigger rod 30. In the absence of a fire or other thermal actuation, the transverse shear strength of the fusible link portions 70 and 71 is sufficiently great to withstand the extensible force of the spring 54 acting on the trigger rod 30 thus to retain the trigger rod 30 in its quiescent state.

A fusible nut 75, responsive to a predetermined temperature, is also located adjacent to the plug 21 in the discharge opening 22 of the sprinkler head 10. The fusible nut 75 provides a safeguard against the expulsion of rod 20 in the event that the fusible link 69 is inadvertently actuated and also prevents an accumulation of dirt and grime in the discharge opening 22 which may otherwise affect the expulsion of rod 20 from the sprinkler head in the event of fire.

If both the fusible link 69 and the fusible nut 75 have been thermally actuated, the sprinkler head 10 is actuated to permit the extinguishant to be discharged from the discharge opening 22 in a predetermined pattern. A fusing of the portions 70 and 71 of the fire-responsive element 69 releases the retaining force exerted against the head portion 60 of the trigger rod, permitting the rod to be axially displaced by the force of the spring 54 exerted through member 57 against the shoulder of annular member 59. The limited axial movement of the rod 30 is sufficient to free the protruding member 31 from its engagement with the opening 32 in expellable rod 20.

The pressure of the extinguishant against the plug 21 causes the plug and rod 20 to be expelled from the discharge opening 22. As an alternative, a chain or wire may be secured to the rod 20 to permit its ready release without allowing the rod 20 to fall to the surface below the sprinkler head 10. As another alternative, the tongue and groove relationship between the protruding member 31 and the opening 32 may be replaced with other suitable releasable connections. For example, the distal end 38 of the rod 30 may be bifurcated wherein the bifurcations are positioned in diametrically-opposed recesses in the distal end of the rod 20. In any event, the spring 54 must have sufficient strength to overcome the frictional engagement of the end connections used as well as the frictional engagement of the rod 30 with the openings 41 and 67 by a suitable margin of safety.

It is a feature of the invention that the pressure necessary to expel the plug 21 from the discharge opening 22 may be selectable in accordance with the needs of the system. In a multiple sprinkler head system, the placement of the heads is determined in part by the spray characteristics of the nozzle. In turn, the spray characteristics are in large measure a function of the pressure of the extinguishant supplied to the nozzle. Thus, the size, physical characteristics or material of plug 21, or in particular, the seal 26, may be selected to prevent the expulsion of the plug member until a minimum extinguishant pressure is available, even after the trigger mechanism has been released as heretofore described. The minimum pressure at which the head may be opened is determined by the pressure necessary to produce an acceptable extinguishant spray from the sprinkler head and at which pressure, actuation of the sprinkler head would have an adverse effect on the spray patterns or other sprinklers in the system which have already opened.

It is another feature of the invention to provide means to modulate the flow of extinguishant from a predetermined maximum to some minimum flow which will continue to produce an acceptable spray characteristic from the sprinkler head and maintain an inlet pressure to the system which permits satisfactory operation of previously-opened sprinkler heads. Thus, a pressurized bellows assembly, designated generally at 76, comprises a fixed member 77 secured to a pair of accordian members 78 and 79 secured respectively to an axially-displaceable, movable member 80.

Accordian members 78 and 79 define a closed annular cavity 85 which contains a predetermined quantity of compressible material, for example, an inert gas. When the pressure of the extinguishant at the inlet to the sprinkler head is at its maximum for the system, for example, when no other sprinkler heads in the array have been actuated, the volume of the closed cavity 85 is at a minimum since the pressure within the cavity seeks to balance the inlet pressure of the extinguishant. Under that condition, the distance between the fixed member 78 and the plug member 80 is at its minimum, permitting a maximum flow of the extinguishant to the nozzle orifice 82 through the passage designated generally at 83. When the inlet pressure of the extinguishant decreases, for example, from increased demands on the system by the actuation of other sprinkler heads, the flow modulating assembly 76 operates to achieve a hydrostatic balance. Since the quantity of compressible fluid in cavity 85 is fixed, the volume of cavity 85 increases until the pressure exerted from within the cavity 85 is equal to the pressure of the extinguishant on the exterior of the cavity.

Because the cavity 85 is incapable of circumferential expansion, the distance between the fixed member 78 and the plug member 80 increases to a maximum, thus constricting the effective discharge area of the nozzle orifice 82. When the area of the nozzle orifice 82 is thus constricted, the flow rate of the extinguishant is reduced, so that the spray pattern of the extinguishant from the sprinkler head is maintained and the inlet pressure to the sprinkler head is increased to maintain a higher inlet pressure to the overall system.

It is another feature of the invention that the flow modulating assembly 76 and the nozzle orifice 82 may be designed to eliminate the flow of extinguishant from the sprinkler head 10 in the event that the inlet pressure falls below a predetermined level. Thus, the total demand for extinguishants from the supply system may be maintained within the capabilities of the system whether the flow discharge rate is modulated or eliminated.

Still another significant advantage of the sprinkler head according to the invention resides in the fact that the invention may be used for a wide range of extinguishants such as from water to fully hydrolized ablative gel. This feature lends an added dimension to existing systems which may ultimately be converted to an ablative water extinguishant, or for use in ablative water systems having a serve capability which uses water as the extinguishant.

The conventional wisdom relating to the present-day sprinkler heads includes the knowledge that spray patterns other than circular may be desirable to minimize the unprotected floor area beneath the sprinkler head. FIGS. 3 through 5 indicate structural features of or additions to the base of the discharge portion 14 of the sprinkler head to provide rectangular or square extinguishant flow patterns.

In FIG. 3, a plurality of radially extending, generally V-shaped notches 89 are in communication with the discharge opening 22 and with the exterior of the sprinkler head. The extent of the flow pattern is determined by the maximum width of the notch, the depth of the notch, the flow rate of the extinguishant and the like.

FIG. 4 depicts an alternative embodiment of the discharge portion, designated at 90, equivalent to the discharge portion 14 of a sprinkler head 10 according to the invention. The discharge portion 90 includes a cavity defined by a cylindrical upper portion 91 and a lower portion 92. Upper portion 91 is defined by a cylindrical surface which merges into a flow passage defined by a cone which has been intersected by a right parallelepiped having an axis parallel to the axis of the core. Thus, a plurality of surfaces 93 are generated which define portions of planes which are also generally parallel to the axis of the conical portion 92. Each of the surfaces 93 also defines an arc-like segment 94 having an apex defined by the shortest line on the conical surface of the conical portion 92 from the cylindrical surface 20. The structure thus described is capable of producing a non-circular spray pattern.

Thus it will be appreciated that by this invention there is provided a highly effective sprinkler head which may be used with a wide range of extinguishant by which the aims and the objects of the invention are achieved.

Claims

What is claimed is:

1. A sprinkler head comprising a body having an inlet portion for receiving a supply of fire extinguishant at an inlet pressure and a discharge portion defining a discharge opening; plug means secured to said body to close said discharge opening when said sprinkler head is in its quiescent state for preventing a flow of extinguishant through said discharge opening; a trigger member having a portion thereof in engagement with said expellable means when said sprinkler head is in its quiescent state for locking said expellable means in said body; a fusible link; a spring for freeing said trigger member from said expellable means when said fusible link is actuated; a nipple member connected to said housing and defining an opening for receiving said trigger member; a coupling secured to said nipple member and defining a cavity, said spring being located about said trigger member in said cavity between said nipple member and a shoulder defined on said trigger member; a housing for said fusible link; and a base secured to said housing and to said coupling member; said base and said housing defining an additional opening, a portion of said trigger member being located in said additional opening and being retained in a first position by said fusible link, said trigger member adapted to assume a second position axially displaced from said first position when said fusible link is actuated, whereby said expellable means is ejected from said sprinkler head by the force of the inlet pressure of said fire extinguishant acting on said expellable means.

2. A sprinkler head comprising a body having an inlet portion for receiving a supply of fire extinguishant at an inlet pressure, a discharge portion defining a discharge opening, and a nozzle orifice; expellable means for preventing a flow of extinguishant through said discharge opening when said sprinkler head is in its quiescent state; fire-responsive means, including a fire-sensing member for locking said expellable means in said body when said sprinkler head is in its quiescent state and unlocking said expellable means when said fire-sensing member is actuated to permit the ejection of said expellable means from said sprinkler head by the force of the inlet pressure of said fire extinguishant acting on said expellable means; and pressure-responsive means for varying the effective area of said nozzle orifice as a predetermined function of the inlet pressure, said pressure responsive means comprising a fixed member, a moveable member cooperating with said nozzle orifice to vary the effective area thereof, and a plurality of accordion-like members secured to said fixed member and said moveable member; said fixed member, said moveable member, and said plurality of accordion-like members defining a cavity adapted to contain a predetermined quantity of compressible fluid, whereby the volume of said cavity varies as a function of the inlet pressure so that said moveable member controls the effective area of said nozzle orifice in such a manner that a predetermined extinguishant spray pattern is effectively maintained for extinguishant inlet pressures which vary from a predetermined maximum to a predetermined minimum.

3. A sprinkler head as defined in claim 2 wherein the flow of extinguishant is caused to cease at said predetermined minimum extinguishant inlet pressure by the structural cooperation of said moveable member and said nozzle orifice.

4. A discharge head for use in a fixed fire extinguishing system comprising a body member having an inlet for connecting to a source of extinguishant and an outlet for permitting discharge of said extinguishant from said body member, said body member defining an extinguishant flow path between said inlet and outlet, releasable means normally disposed in said body member for preventing fluid flow from said outlet, a latching member engaging said releasable means in said body member for retaining said releasable means in said outlet, a portion of said latching member extending out of said flow path, and control means cooperating with said portion of said latching member and responsive to a predetermined fire situation in the vicinity of said body member for permitting the disengagement of said latching member from said releasable means and the release of said releasable means from said outlet.

5. The discharge head of claim 4 wherein said releasable means comprises a rod engaged by said latching member and a plug member connected to said rod and extending in said outlet.

6. The discharge head of claim 5 wherein said control means is in the form of a fusible link, and wherein said latching member is spring loaded and is connected between said rod and said fusible link so that said rod is released upon collapse of said fusible link in response to said predetermined fire situation.