Patent Publication Number: US-11027160-B2

Title: Fire sprinkler system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/661,302 filed Mar. 18, 2015, which claims priority to Provisional Patent Application No. 61/955,253 filed Mar. 19, 2014 and also to Provisional Patent Application No. 62/019,527 filed Jul. 1, 2014, the entire disclosures of which are hereby incorporated by reference and relied upon. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates generally to methods and systems for extinguishing fires, and more particularly to sprinklers of such systems. 
     Description of Related Art 
     Fire suppression systems have been used in the United States to protect warehouses and factories for many years. In a fire suppression system, a fire sprinkler is positioned near the ceiling of a room where hot “ceiling jets” spread radially outward from a fire plume. When the temperature at an individual sprinkler reaches a pre-determined value, a thermally responsive element in the sprinkler activates and permits the flow of water as a water jet through a duct toward a deflector. The deflector redirects the water jet into thin streams or “ligaments” that break up into droplets due to surface tension. The water droplets deliver water to the burning material, reduce the combustion rate, wet the surrounding material, reduce the flame spread rate, cool the surrounding air through evaporation and displace air with inert water vapor. 
     Fire suppression systems can comprise a water distribution piping system to which a plurality of spaced-apart fire sprinklers are connected. Fire suppression systems and methods of installation are described in detail in my U.S. Pat. No. 8,602,118 (issued Dec. 10, 2013) and U.S. Pat. No. 8,733,461 (issued May 27, 2014), the entire disclosures of which are hereby incorporated by reference and relied upon. 
     When fire sprinkler heads are located close to each other, the risk of “cold soldering” becomes a concern. Cold soldering occurs when one fire sprinkler disperses a fire suppressing or extinguishing substance that directly cools a nearby fire sprinkler and prevents the latter fire sprinkler from properly responding and activating. Prior art pendant-type sprinklers are held closed by a trigger in the form of either a heat-sensitive glass bulb or a two-part metal link held together with fusible alloy. The trigger applies pressure to a closure element which acts as a plug in the sprinkler nozzle to prevent water from flowing until the ambient temperature around the sprinkler reaches the design activation temperature of the individual sprinkler head. Sprinkler heads located in open structures (i.e., not adjacent a wall, ceiling or beam) are commonly oriented vertically overhead (either pointing up or pointing down) and are provided with a deflector positioned in the path of water spray from the nozzle. The deflector redirects the vertically-discharged water jet into thin streams or “ligaments” that spread out uniformly in all directions (i.e., in a 360° discharge pattern) above burning materials to reduce the combustion rate, wet the surrounding material, reduce the flame spread rate, cool the surrounding air through evaporation and displace combustion air with inert water vapor. 
     Side-discharge sprinklers are a special type of fire sprinkler used in applications immediately adjacent a wall or beam or other blocking structure, as shown in  FIGS. 1 and 2 , which are taken from U.S. Pat. No. 7,331,399, the entire disclosure of which is hereby incorporated by reference. Side-discharge sprinklers are typically mounted in a horizontal orientation, as contrasted with the more common types of sprinkler heads which are mounted vertically up or vertically down (pendant). A typical side-discharge sprinkler can discharge approximately the same flow rate of water as the standard vertical mount design, but the distribution pattern of the water from a side-discharge sprinkler is directional and dispersed over a region generally about 180° (as compared with 360° in a vertical mount sprinkler). That is, a side-discharge sprinkler can discharge the same amount of water over time as that of a standard vertical mount type, but will distribute the water over roughly half the area due to is half-circle discharge pattern. As a result, the density of water per unit area of ground is greater for a side-discharge sprinkler. In fire suppression sciences, it is widely understood that the more water per unit time that can be delivered to burning material, the greater the reduction of combustion rate, better wetting, and so forth. 
     Despite their ability to discharge a greater water density, side-discharge sprinklers cannot be used in open surround conditions (i.e., located in the middle space between two structural beams (or girders, trusses, etc.) due to their inherent directional discharge patterns. In open surround conditions, a 360° discharge pattern is almost always used. Furthermore, side-discharge sprinklers cannot be positioned near one another due to the aforementioned cold soldering problem. 
     There is a need in the fire suppression and extinguishment field to create an improved fire sprinkler system that delivers a maximum density of water per unit area of ground but without the risk of cold soldering the trigger of nearby sprinkler heads. 
     BRIEF SUMMARY OF THE INVENTION 
     According to a first aspect of this invention, an over-head fire suppression system is provided for warehouse applications. The over-head fire suppression system is configured to disperse a fire suppressing liquid in a steam-like downward trajectory onto a storage area below. The system comprises an elongated tubular supply line configured as a conduit to carry pressurized fire-suppressing liquid. The supply line has a longitudinal centerline. The supply line has right and left sides separated by a vertical plane passing through the longitudinal centerline. A plurality of side-discharge fire sprinklers are coupled directly to the supply line. Each fire sprinkler is configured to receive a flow of fire-suppressing liquid from the supply line. Each fire sprinkler includes a deflector configured to disperse the flow of fire-suppressing liquid in a downward trajectory over a non-circular coverage area defined by a major diameter and a shorter minor diameter. The plurality of fire sprinklers are arranged so that half of the fire sprinklers are disposed on the right side of the supply line and the other half of the fire sprinklers are disposed on left side of the supply line in alternating fashion such that every other the fire sprinkler is disposed on the right side of the supply line with the other the fire sprinklers disposed in interleaved fashion on the left side of the supply line. 
     According to another aspect of this invention, an over-head fire suppression system for warehouse applications is configured to disperse a fire suppressing liquid in a steam-like downward trajectory onto a storage area below. The system comprises a first elongated tubular supply line configured as a conduit to carry pressurized fire-suppressing liquid. The first supply line has a longitudinal centerline and right and left sides separated by a vertical plane passing through the longitudinal centerline. A plurality of side-discharge first fire sprinklers are coupled directly to the right side of the first supply line. Each first fire sprinkler is configured to receive a flow of fire-suppressing liquid from the first supply line. Each first fire sprinkler includes a deflector configured to disperse the flow of fire-suppressing liquid in a downward trajectory over a non-circular coverage area. Each first fire sprinkler is separated from the next adjacent the first fire sprinkler by a generally equal spacing interval. A second elongated tubular supply line is configured as a conduit to carry pressurized fire-suppressing liquid. The second supply line has a longitudinal centerline and right and left sides separated by a vertical plane passing through the longitudinal centerline. The second supply line is disposed parallel to the first supply line with the left side of the second supply line facing toward the right side of the first supply line. A plurality of side-discharge second fire sprinklers are coupled directly to the left side of the second supply line. Each second fire sprinkler is configured to receive a flow of fire-suppressing liquid from the second supply line. Each second fire sprinkler includes a deflector configured to disperse the flow of fire-suppressing liquid in a downward trajectory over a non-circular coverage area. Each second fire sprinkler being separated from the next adjacent the second fire sprinkler by a generally equal spacing interval. The spacing interval between the first fire sprinklers is generally equal to the spacing interval between the second fire sprinklers. The non-circular coverage areas from the first fire sprinklers are interlaced between the non-circular coverage areas from the second fire sprinklers. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein: 
         FIG. 1  is a simplified perspective view of a building interior in which are installed prior are side-discharge sprinklers along opposing faces of structural beams; 
         FIG. 2  is a cross-sectional view taken generally along lines  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a perspective view of a building interior as in  FIG. 1  but fitted a fire suppression system according to one embodiment of the present invention; 
         FIG. 4  cross-sectional view as taken generally along lines  4 - 4  of  FIG. 3  showing of a section of supply line supporting two side-discharge fire sprinklers arranged in opposite-facing directions and where the deflector of one fire sprinkler is in partial cross-section; 
         FIG. 5  is a perspective view of the section of supply line shown in  FIG. 4  again with the deflector of one fire sprinkler depicted in partial cross-section; 
         FIG. 6  is a simplified view of the present fire suppression system in which one side has been activated to suppress a fire below; 
         FIG. 7  is a perspective view showing the sprinkler system of one embodiment installed above storage items and with two fire sprinkler heads activated in response to heat rising from the flues in-between the storage items; 
         FIG. 8  is a top view showing two parallel supply lines arranged over a row of storage items, each supply line being fitted with opposite-facing sprinkler heads according to one embodiment of the present invention, and further illustrating exemplary spray discharge patterns from several of the sprinkler heads to illustrate an exemplary coverage strategy; 
         FIG. 9  is a view as in  FIG. 8  but further superimposing a prior art fire suppression system comprising four supply lines with omni-directional heads arranged in the common 10′×10′ grid pattern for comparison purposes; and 
         FIG. 10  is a perspective view as in  FIG. 4  but showing an optional adjustment scheme whereby the coverage patterns can be individually adjusted to suit the storage conditions. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the figures, wherein like numerals indicate like or corresponding parts throughout the several views, a fire suppression system according to one exemplary expression of the present invention is generally shown at  20  in  FIGS. 3-9 . In  FIG. 3 , the fire suppression system  20  is shown located in the interior storage space of a building structure. The building structure may be a warehouse having a floor  22 , and at least three beams  24  suspended over the floor  22 . The beams  24  are preferably steel I-shaped rafters, but may be any suitable structural member made from any suitable material and shaped in any suitable manner. The beams  24  are typically arranged parallel to one another and spaced evenly apart by an interior bay length L 1 . In this example, the three beams  24  may be consider first, second and third beams  24 , with the second beam being disposed in between the first and third beams  24 . Each beam  24  is supported by a pair of substantially vertical uprights or posts  26  spaced apart from one another by an interior bay width W 1 . In some constructions, purlins (not shown) may be placed perpendicularly across the beams  24  to support a ceiling or roof  27 . In the example of  FIG. 3 , the ceiling or roof  27  is oriented at a skewed or pitched angle relative to the floor  22 , however flat roof constructions are also certainly possible as suggested by  FIG. 6 . In any event, the beams  24  are oriented so as to run perpendicular to the high-point of the roof which, in  FIG. 3 , is illustrated in the form of a ridge  28 . That is to say, the pitch of the roof  27  typically runs parallel to the beams  24  and parallel to the W 1  dimension. In steel frame structures like those depicted in  FIGS. 1 and 3 , the regions between adjacent beams  24  and spanning their full width are often referred to as bays. Each bay is therefore defined by the above-noted length and width variables L 1  and W 1 . Commonly, the bay width W 1  is at least 20 feet (6 m) and the bay length L 1  is at least 20 feet (6 m), although often one or both of these measures are greater. The pitch of the roof  27  slopes along the bay width W 1 . 
     The fire suppression system  20  includes at least one, but preferably a plurality of supply lines  30 . Each supply line  30  comprises a fluid-conducting conduit or pipe suspended below the roof  27  of the structure, such as from its purlins (not shown) or by other suitable accommodation. The several elongated tubular supply lines  30  within a building structure are fed, usually via a common manifold, with pressurized fire-suppressing liquid, such as water or other suitable material, from a source under pressure. The supply lines  30  may be located in the middle space between two structural beams  24  (or girders, trusses, etc.) in the building structure. That is, the supply lines  30  are advantageously located generally along the centerline of each bay area, with one supply line  30  per bay, however these are not requirements and other configurations are certainly possible. Therefore, in applications with multiple supply lines  30 , the supply lines  30  are arranged generally parallel to one another under the roof  27  so that they all extend perpendicular (or at least not parallel) to the ridge  28  or other high point feature of the roof  27 . 
     Each supply line  30  has a longitudinal centerline A with right C and left B sides separated by an imaginary vertical plane P that passes through the longitudinal centerline A, as shown in  FIGS. 4 and 5 . In situations where multiple supply lines  30  are used, one supply line  30  may be deemed a first supply line  30  and the next adjacent supply line a second supply line  30 . The second supply line  30  is typically disposed parallel to the first supply line  30  and is perpendicularly spaced to either the left B or the right C therefrom. The first and second supply lines  30  may be generally identical to one another such that which is the first and which is the second is of little consequence. Because the first and second supply lines are next to one another, the right side C of one will face the left side B of another. 
     Side-discharge style fire sprinklers  32 , sometimes referred to herein as a sprinkler head or merely a head, are part of an installed active fire suppression system disposed in a warehouse or other space needing a high level of fire protection. The fire sprinklers  32  are disposed in series along each supply line  30  at regular intervals. In some applications, the interval spacing may be about two-to-ten feet depending on design criteria. In the accompanying illustrations, each fire sprinkler  32  is shown approximately two-feet from the next adjacent sprinkler head  32  on the same supply line  30 , although the adjacent sprinkler heads  32  are aimed in opposite directions. Preferably, each fire sprinkler  32  is of the side discharge type, as opposed to a vertical type like the ubiquitous pendant head. That is, the sprinkler heads  32  are designed to be attached to the supply line  30  so that they extend outwardly in a horizontal or generally horizontal (i.e., non-vertical) direction. Typical prior art side discharge sprinkler heads disperse water over a generally semi-circular area. While standard prior art side discharge sprinkler heads are suitable for use with the present invention, in the preferred embodiment the sprinkler heads  32  are specially configured to disperse water over a long, narrow, well-defined, coverage area  64  which many be elliptical, oval or rectangular. 
     The plurality of fire sprinklers  32  are arranged along a common supply line  30  so that half of the fire sprinklers are disposed on the right side C of the supply line  30  and the other half of the fire sprinklers  32  are disposed on left side B of the supply line  30 . At the location where each fire sprinkler  32  is intended to adjoin the supply line  30 , a saddle  34  is fitted in place. Each saddle  34  perpendicularly intersects the supply line  30 . The saddle  34  is provided with a central aperture (not visible) that fluidly connects with the internal conduit region of the supply line  30  so that an outflow of fire-suppressing liquid can travel from the supply line  30  into the central aperture when the sprinkler head  32  is activated. The surrounding body of the central aperture has a threaded interior surface that is designed to mate with external threads of the sprinkler  32 . During fabrication of a fire suppression system, an installer will typically drill holes in the supply line  30  at the locations where fire sprinklers  32  are desired. Half of the holes will be drilling on the left side L, and the other half on the right side R of the supply line  30 . Saddles  46  are then welded or otherwise sealed to the supply line  30  over the drilled holes. Finally, fire sprinklers  32  are screwed into respective saddles  34  prior (or subsequent) to hanging the supply line  30  from the supporting structure in the warehouse or other building structure similar to that shown in  FIG. 3 . 
     Two supply lines  30  are illustrated in  FIG. 3 , which for purposes of discussion may be referred to as the first and second supply lines  30 . The spacing between the first supply line  30  and the second supply line  30  is approximately equal to the bay length L 1  of either bay. Because of the wide spacing between adjacent first and second supply lines  30  enabled by this invention, as will be described below in connection with  FIGS. 8 and 9 , the installer is afforded substantially greater freedom to locate supply lines  30  far from the beams  24  which might otherwise present an obstruction to the spray pattern.  FIG. 3  represents a scenario where the supply lines  30  are set so that only one supply line  30  is between each adjacent pair of beams  24 . This represents a substantial reduction in the number of supply lines  30  to be installed as compared with prior art systems, and therefore a significant reduction in system/installation costs and long-term maintenance expenses, as well as an improvement in fire suppression performance. 
     The fire suppression system  20  shown in  FIGS. 3-9  depicts use of a special application listed side-discharge-type sprinkler. The side-discharge sprinkler  32  includes a threaded nipple  36  that is configured with external thread forms to be screwed into a threaded female saddle  34 . A frame  38  is supported from the nipple  36 . The frame  38 , in turn, supports a trigger  40  and a deflector. The deflector can be any device that shapes the dispersion of water, including nozzle-like elements as well as more traditional deflecting and diffusing features. In the illustrated examples, the deflector includes an elongated, nozzle-like hood  42  having a downward slant to efficiently direct water flow so as to achieve a desired coverage area with minimal splash or turbulence. The deflector also includes an optional baffle  44 . The baffle  44  in these examples is a thin, strip-like element that is supported below the hood  42 . The baffle  44  is somewhat cantilevered and arranged to extend outwardly with the hood  42 , i.e., perpendicular to the supply line  30 . The width of the baffle  44  is considerably less than the interior width of the hood  42  so that a substantial quantity of discharged water will flow unaffected around the sides of the baffle  44 . In use, the baffle  44  provides at least two beneficial functions. Prior to activation of a fire sprinkler  32 , the baffle  44  provides a measure of passive protection to the thermally responsive element  40  from the spray of an adjacent sprinkler  32  so as to reduce the possibility of cold soldering. In cases where an adjacent sprinkler  32  is earlier activated, the incoming fluid spray will be at least partially deflected by the baffle  44 . After activation of a fire sprinkler  32 , the baffle  44  assists like a dynamic flow control vane to help evenly distribute fire suppressing liquid within the coverage area. The deflector is also shown including a downwash section  46  which, like the baffle  44 , also acts as a splash shield and helps evenly distribute fire suppressing liquid within the coverage area—particularly below the supply line  30 . Naturally, the deflector shown in the accompanying Figures may be highly modified with additional flow controlling features in order to achieve a well-defined coverage area  64  with water density distribution characteristics as may be desired. 
     A duct extends through the nipple  36  to create an internal flow path for water or other fire suppressing substance from the supply line  30  along an outflow axis. The outflow axis is generally perpendicular to the longitudinal extent of the supply line  30 , and in one preferred embodiment is generally horizontal. That is to say, the outflow axis may be generally parallel to the floor  22 , however as suggested in phantom in  FIG. 4  the outflow axis may be skewed from horizontal in certain applications as a means to achieve the desired spray coverage area  64 . A plug-like closure element that is mated with the trigger  40  blocks the duct until activated by an elevated internal building temperature. Once the trigger  40  is tripped, the closure is ejected and water (or other substance in the supply line  30 ) rushes out under pressure through the duct along the outflow axis and collides with the deflector to spray over a non-circular individual coverage area  64 . The trigger  40  is a thermally responsive element that responds to heat from a fire plume and then releases the closure, thereby permitting the flow of the fire suppressing or extinguishing substance. The thermally responsive element is preferably a fusible link assembly comprised of two link halves which are joined by a thin layer of solder. When the rated temperature is reached, the solder melts and the two link halves separate, allowing the sprinkler  32  to activate and water to flow. Alternatively, the trigger  40  may be of the glass bulb type which is designed to shatter when the rated temperature is reached, or any other suitable device or method. The trigger  40  may include any suitable method or device to block the flow of the fire suppressing or extinguishing substance through the duct until activated. 
     As stated above, on any given sully line  30 , half of the sprinklers  32  are placed on the right side C and the other half on the left side B. More preferably, the plurality of fire sprinklers  32  are arranged in alternating fashion on the right C and left B sides of the supply line  30  such that every other fire sprinkler  32  is disposed on the right side C of the supply line  30  with the other fire sprinklers  32  disposed on the left side B of the supply line  30 . Thus, every other side-discharge-type sprinkler  32  is set in an opposite-facing direction along the same supply line  30 . In this arrangement, any two adjacent sprinklers  32  may be considered a pair with one of the sprinklers  32  pointing left and the other fire sprinkler  32  pointing right. The pair of fire sprinklers  32  may be identical to one another or distinct. The drawings describe the embodiment where the sprinklers  32  on the left side B are longitudinally offset from the sprinklers  32  on the right side C. However, in another contemplated application the sprinklers  32  are located in direct back-to-back relationship. 
     In order to effect this opposite-facing arrangement, the saddles  20  of the respective sprinklers  32  are fixed on horizontally opposite sides of the same supply line  30 , so that their respective outflow axes each perpendicularly intersect the supply line  30 . As shown by the phantom lines in  FIG. 4 , it is contemplated that one saddle  34  (or both) may be placed so that the sprinkler  32  extends at a skewed angle relative to horizontal as an alternative to bending or otherwise adjusting the positon of the hood  42 . Indeed, some applications may lend themselves to orienting the two opposite-facing sprinkler heads  32  at different angles relative to horizontal. As an example, the right side sprinkler head  32  may be angled 5 degrees below horizontal, and the left side sprinkler  32  angled 10 degrees below horizontal in order to aim the sprayed water relative to the overall height and location of any storage items. 
     In order to address the potential of cold soldering due to two sprinkler heads  32  being located so close to one another, at least one blocking surface is supported on the supply line  30  in-between the two fire sprinklers  32 . That is, the blocking surface is a component of the fire suppression system  20  and as such is supported by the supply line  30  or by a component (e.g., a sprinkler head  32 ) which in turn is supported by the supply line  30 , rather than comprising a feature of the building structure like that shown in  FIGS. 1 and 2 . The blocking surface is configured to block fire-suppressing liquid that is discharged from one of the fire sprinklers  32  from contacting the other fire sprinkler  32  which could otherwise negatively influence the trigger  40  of the second fire sprinkler  32  from activating in a timely fashion. The blocking surface may take many different forms. That is to say, without the blocking surface, the close-spacing of these two side-discharge sprinklers  32  would cause spray from the first-activated sprinkler  32  to over-cool the adjacent (but not yet activated) sprinkler  32  and thereby delay its activation (i.e., not allow the second sprinkler  32  to operate according design specifications). However, with the blocking surface both side-discharge sprinklers  32  can operate essentially independent of one another and fully according to their design specifications. 
     In the illustrated embodiment, the blocking surface comprises the unique shape of the deflector in which the trigger  40  is substantially shrouded and enclosed. Indeed, the trigger  40  is only exposed from the discharge end of the deflector and from below, where a gap in the downwash member  46  is provided. This distinctive configuration allows heat rising from a fire to directly enter the deflector and be channeled toward the trigger  40 . The deflector in fact collects and concentrates the heat onto the trigger  40  thereby encouraging early activation. However, the trigger  40  is otherwise shrouded from water spray caused any other nearby sprinklers  32 . As a result, the possibility of cold soldering is substantially eliminated. 
     In this manner, the deflector creates a cave-like shell around the sides and top of the trigger  40 ; only the discharge direction and the bottom of the cave-like enclosure are open. Accordingly, the blocking surface fulfills several functions simultaneously to enable effective use of side-discharge-type sprinklers arranged on opposite-facing sides of the same supply-line  30  in a warehouse application. These include acting as a splash guard to prevent water that sprays sideways or rearwardly (e.g., in response to contact with an obstruction) from reaching the trigger  40  of a nearby sprinkler  32 , reflecting heat onto the unactuated trigger  40  of the sprinkler  32  so that the trigger  40  will activate in a timely fashion if/when needed, and shaping the water flow to achieve a desired coverage area  64  and water density distribution. 
     In another contemplated variation (not shown), a standard prior art side-discharge sprinkler head is used and the blocking surface comprises a backer plate that is associated with each sprinkler head. The backer plate could be a formed sheet-metal member and arranged to overhang the sprinkler like a small roof. Such a backer plate could be integrated with the deflector and/or the frame of a sprinkler head. In any event, the backer plate must be effective to negate the condition known as cold-soldering that could otherwise arise in the event a first sprinkler is set-off prior to the second sprinkler. 
       FIG. 6  shows two side-discharge sprinklers  32  arranged opposite-facing directions above a bay area between two adjacent beams  24  and covered by a roof  27 . In this illustration, a fire has broken out on the right side of the bay area below the fire suppression system  20 , setting off the right side-discharge sprinkler  32  but not the left side-discharge sprinkler  32 . As water (or other liquid substance) sprays from the right side-discharge sprinkler  32 , the blocking surface associated with the right side-discharge sprinkler  32  deflects the water spray so that it cannot contact the left side-discharge sprinkler  32 . Meanwhile, the left side-discharge sprinkler  32  is poised to activate in a timely fashion if/when needed. This ready condition of the left side-discharge sprinkler  32  is passively facilitated by its associated blocking surface. In particular, the blocking surface of the left side-discharge sprinkler  32  acts as a shield that prevents collateral overspray and water splashes from contacting its unactuated trigger  40  (i.e., to prevent cold-soldering). Furthermore, the blocking surface of the left side-discharge sprinkler  32  reflects and funnels heat from the fire toward its trigger  40  so that its activation timing is not adversely affected (i.e., delayed) by the ambient water spray from the right side-discharge sprinkler  32 . 
     In  FIG. 7 , storage items  54  are shown disposed on the floor  22  in the warehouse. In a warehouse, storage items  54  are frequently stacked or arranged in long rows. Also commonly, the storage items  54  may be stacked in elongated storage racks, generally indicated at  56 , which in turn are disposed on the floor  22  in the warehouse. In  FIG. 7 , one such storage rack  56  is shown. Commonly, a warehouse facility will arrange many storage racks  56  in opposite-facing pairs separated by aisles large enough for a forklift to maneuver. The common storage rack  56  has a plurality of shelves  58  upon which are placed the storage items  54 . Oftentimes, the storage items  54  are palletized, or otherwise carried on standard 4×4 pallets to facilitate handling with a forklift (no shown). Of particular note is the overall height of the storage items  54  either standing free or when arranged in rows. When storage items  54  are stacked in shelves  58  of the storage racks  56 , the lofty storage items  54  on the uppermost shelf  56  will define the overall height, which is the highest level or region of goods that must be protected by the fire suppression system  20 . 
     Within this context, the fire suppression system  20  is suspended from above in the warehouse, at an elevation that is greater than the overall height of the storage items  54  disposed below. In the event of a fire, wherein it is presumed that the locus of the fire is in or at a storage item  54  somewhere in a storage rack  56 . The arrangement of storage racks  56  and the typical placement of palletized storage items  54  on the various levels of shelves  58  in the storage racks  56  establish a plurality of transverse flues  60  and one longitudinal flue  62 . These flues  60 ,  62  are indicated by wide directional arrows. Naturally, such flues  60 ,  62  can exist in solid-pile (non-racked) type storage arrangements. The transverse flues  60  are formed in the gaps between adjacent storage items  54 . The longitudinal flue  62  is created in the gap between two storage racks  56  when arranged back-to-back. The importance of these flues  60 ,  62  becomes relevant when a fire is present in or adjacent one of the storage items  54 . Perhaps a worst-case scenario in terms of fire suppression is when a fire originates between two storage racks  56  arranged back-to-back (i.e., in the longitudinal flue  62  area) at or near the floor  22 , which is suggested by heat arrows rising from the flues  60 ,  62  in  FIG. 7 . This is the most distant and difficult to reach region for fire suppressing liquid dispersed from a fire sprinkler  32 . 
     The fire produces hot combustion gases that travel upwardly through the narrow flues  60 ,  62  like chimneys. When the escaping heat is sufficient to activate at least one nearby overhead fire sprinkler  32 , water (or other fire suppressing liquid) will be discharged. In order to be effective, the water must travel down the very same flues  60 ,  62  through which heat from the fire is rising up. The rising heat, concentrated within the narrow passageways of the flues  60 ,  62 , will vaporize the descending water spray unless sufficient quantities of water and/or large enough droplet sizes can be applied to overpower the heat. The greatest success at fire suppression will be achieved when, at the initial stages of a fire, a maximum amount of water is applied to the flues  60 ,  62  directly above the fire locus. 
     The present fire suppression system  20  is configured and arranged so that, at all stages of a fire but particularly at the initial stages, a maximum amount of water is applied to the flues  60 ,  62  laying directly above the fire so that very little spray is wasted dousing nearby (non-burning) storage items  54 . Furthermore, the fire suppression system  20  is capable of generating a water curtain effect that resists spread of the fire to adjacent storage racks  56 . In the event of fire in a storage rack  56 , the activated fire sprinklers  32  will create a beneficial water curtain in the adjacent aisles and/or flues  60 ,  62  to discourage fire spread, thereby helping to contain the fire in the smallest possible region. This invention is uniquely designed to combat fires in warehouse settings where storage items  54  are tightly stacked or arranged and water from activated fire sprinklers  32  must travel into narrow flues  60 ,  62  to reach a fire. 
       FIG. 8  is a simplified top view of a fire suppression system  20  according to one embodiment of this invention where two adjacent supply lines  30  (i.e., first and second) are disposed in a building structure, perhaps arranged along the centerlines of two adjacent bay areas between three adjacent beams  24  like that shown in  FIG. 3 . As an example, the spacing between the two adjacent supply lines  30  may be about twenty-five feet. Of course, an installer or a qualified spec writer may decide that the spacing between the two adjacent supply lines  30  should be larger or smaller. Each sprinkler head  32  is schematically illustrated and arranged in the aforementioned alternating fashion with blocking surfaces protecting its trigger  40 . Furthermore, if one were to rotate  FIG. 8  ninety degrees in a counter-clockwise direction, the left-hand supply line  30  could be considered the “first” and the right-hand supply line  30  the “second.” It is then evident that the fire sprinklers  32  on the right side C of the first supply line  30  face toward the second supply line  30 . And similarly, the fire sprinklers  32  on the left side B of the second supply line  30  face toward the first supply line  30 . In other words, the fire sprinklers  32  on the left side B of the second supply line  30  point toward the fire sprinklers  32  on the right side C of the first supply line  30  somewhat like the cannons of two ancient battleships. 
     As stated previously, each fire sprinkler  32  is configured to disperse an outflow of fire-suppressing liquid over a non-circular individual coverage area  64 . The coverage areas  64  are represented by broken lines in  FIGS. 7-9 , as may be understood as the point of contact with the uppermost surfaces of storage items  54  located on the highest elevation shelves  58  in the storage racks  56 . Standard prior art side-discharge sprinkler heads, which are usually intended for wall-mounted applications, typically disperse water over a generally semi-circular area. While standard prior art side discharge sprinkler heads are suitable for use with the present invention, in the preferred embodiment the deflectors are configured so that the coverage areas  64  are more elongated in shape. The non-circular individual coverage areas  64  from any paired fire sprinklers  32  are contiguous and generally mirrored. If any paired fire sprinklers  32  are placed directly back-to-back along the supply line  30 , then their combined coverage areas  64  would merge and define a generally elliptical or oval or rectangular area. However, in the illustrated examples paired fire sprinklers  32  are longitudinally offset along the supply line  30  so that their respective coverage areas  64  are likewise offset, as well as focused in opposite directions, as shown in the lower right-hand corner of  FIG. 8 . 
     The coverage area  64  from each sprinkler head  32  has a major diameter L 2  which is generally perpendicular to the supply line  30  and a shorter minor diameter W 2  that is generally parallel to the supply line  30 . While the terms “major diameter” and “minor diameter” are suggestive of elliptical geometries, and indeed several of the Figures depict elliptical shapes, it should be understood that coverage areas could have oval or rectangular geometries, or other suitable shape as may be deemed acceptable. The minor diameter W 2  is preferably between about 5% and 100% of the major diameter L 2 , and in some preferred embodiments W 2  is between about 15% and 67% of L 2 . More preferably still, W 2  may be less than 50% of L 2  in order to produce a discharge jet that more closely mimics the powerful stream from a fire hose. The major diameter L 2  is preferably smaller than the perpendicular spacing between the first and second supply lines  30 , and also preferably slightly larger than half the distance between adjacent supply lines  30  to account for some degree of overlap. So in the example of  FIG. 8 , where the distance between adjacent supply lines  30  is shown as twenty-five feet, the L 2  is preferably somewhat greater than twelve-and-a-half feet—perhaps about fourteen feet. Every other sprinkler head  32  located along the same supply line  30  is spaced apart by a spacing distance S. That is to say, when considering only the sprinkler heads  32  on one side (left B or right C) of the supply line  30 , the separation intervals are the spacing distance S, as shown in  FIGS. 3 and 8 . The minor diameter W 2  of the combined coverage area is slightly larger than the spacing distance S to account for some degree of overlap. In one embodiment of the invention, the spacing distance S is between about two feet and ten feet. In the example of  FIG. 9 , the spacing distance S is four feet. In the example where the spacing distance S is four feet, W 2  is preferably somewhat greater than four feet—perhaps about five to six feet which is less than 50% of L 2 . 
     Preferably the sprinklers  32  of this invention are installed in an optional stagger spaced arrangement both along the respective supply lines  30  and also within the structure. The stagger spaced arrangement is designed to redirect the sprays of water into the structure with strategically interwoven coverage areas. According to this arrangement, for each adjacent pair of first and second supply lines  30  extending parallel to one another, opposing sprinkler heads  32  are set in an offset relationship relative to one another. That is, the inwardly facing sprinklers  32  along one supply line  30  are not pointing directly at, i.e., not in line with, the inwardly facing sprinklers  32  of the other supply line  30 . Said another way, the coverage area  64  from a sprinkler  32  on one supply line  30  is longitudinally (i.e., along the length of a supply line  30 ) offset from the coverage area  64  of an opposing sprinkler  32  on the next adjacent supply line  30 . Thus, a person standing on the floor  22  in the building and looking up toward the roof  27  will observe that as between two adjacent supply lines  30  the rightward-pointing sprinklers  32  on the first supply line  30  do not line up in the L 1 /L 2  directions with the leftward-pointing sprinklers  32  on the second supply line  30 ; the heads  32  are in fact staggered in an alternating fashion. Preferably, the off-set is equal to approximately one-half of the spacing distance S, or “S/2” as shown in  FIG. 8 . In the example of  FIG. 9 , where the spacing distance S is four feet, the longitudinal offset is two feet. 
       FIG. 8  shows this stagger spacing arrangement, where the combined elliptical coverage areas  64  are similar in some respects to those described in my co-pending US Patent Publication No. 2015/0034341 published Feb. 5, 2015, the entire disclosure of which is hereby incorporated by reference. However in this present invention the inwardly pointing coverage areas  64  between each adjacent pair of supply lines  30  are offset to one another. Furthermore, according to the illustrated example of this invention, along one supply line  30  each paired set of sprinklers  32  are longitudinally offset from one another by the same half spacing S/2 in a regular alternating pattern. In this manner, a design spacing distance S is calculated or otherwise predetermined to disperse water over the underlying combined coverage areas  64 . The sprinklers  32  on right side C of the first supply line  30  are arranged in-between the opposing sprinklers  32  on the second adjacent supply line  30  (i.e., on the left side B) side so that the inflows of coverage areas  64  applied between these two supply lines  30  are spaced equally with the half spacing distance (S/2). In this manner, the coverage areas  64  are interleaved with one another, and depending on the W 2  and L 2  dimensions may even overlap one another. In the example of  FIG. 8 , the major diameter L 2  of each combined coverage area  64  is optimally distributed into the cove or valley-like regions between the coverage areas  64  in the two opposing sprinklers  32  of the adjacent supply line. Thus, the interlaced coverage areas  64  by two opposing sprinklers  32  achieve and optimal use of water. However, given that water pressure has a direct effect on the actual size of the coverage area  64 , and because water pressure will diminish as more fire sprinklers  32  are activated, it may be desirable to design a fairly generous overlap—on the order of one to three feet—for a single-activated fire sprinkler  32 . It is therefore understood that as water pressure diminishes due to additional fire sprinklers  32  being activated, the modestly shrinking coverage area  64  will remain in an ideal geometric condition with the next adjacent coverage area  64 . Therefore, the degree of overlap needed between adjacent coverage areas  64  is preferably calculated for each installation based on line pressure, supply line  30  sizes and other relevant factors. 
     In the example of  FIG. 8 , the minor diameter W 2  of each coverage area  64  is at least equal to S, and more preferably is between about S and 2S (i.e., between one and two times S). In this example, the major diameter L 2  of each coverage area  64  is greater than half the distance between adjacent supply lines  30  (e.g., &gt;12.5 feet) so that at its farthest end the coverage area  64  reaches into the cove or valley-like space between the coverage areas  64  in the two opposing sprinkler sets  32  of the adjacent supply line  30 . The large lateral reach in the major diameter L 2  direction can be particularly benefitted when installed in a structure fitted with open web type beams  24 , such that the supply lines  30  can be located very near to the ceiling with water sprays easily passing through the open webbings. It is to be understood that the illustrated examples fully contemplate extension of these teachings to buildings that have many bays, with the stagger spacing concepts being repeated between every two adjacent supply lines  30 . 
     A particular advantage of the present invention can be readily appreciated by comparing  FIG. 9 , which overlays a typical prior art sprinkler system with the novel stagger spacing concepts depicted in  FIG. 8 . The prior art system is identified by supply lines  66  (drawn as broken lines) carrying traditional pendant style spray heads  68 . The superimposed prior art system shown here may be of the Early Suppression Fast Response (ESFR) type in which fast response sprinklers  68  are designed to discharge a high effective water density in order to combat a fire plume, particularly in high rack storage applications. In a typical prior art ESFR system, the supply lines  66  are spaced apart ten feet and the sprinkler heads  68  are spaced apart ten feet. This places the prior art sprinkler heads  68  in a ten-by-ten foot grid pattern. 
     As shown in  FIG. 9 , a prior art ESFR system requires about four supply lines  66  to cover the same area as the present suppression system  20  having only two supply lines  30 . The labor savings represented by a 50% reduction is supply line installation is significant. Furthermore, as will be validated below, the supply lines  30  of the present invention can be smaller in diameter than the prior art ESFR supply lines  66 , thus representing a further cost reduction, as well as a weight reduction which translates to smaller supporting brackets and possibly smaller purlins or other structural elements from which the supply lines  30  are hung. 
     The prior art spray heads  68  are shown having the typical circular spray pattern  70  (only one spray pattern  70  shown for simplicity). If the prior art ESFR is presumed to be supplied with water at 52 psi, which is a common specification, and the ESFR spray heads  68  are rated at a 16.8 k-factor, a reasonable assumption, then the discharge rates from each spray head  68  can be calculated at about 121 gallons per minute using the formula:
 
 q=k*p   0.5  
 
Where:
 
     q is the flow rate; 
     k is the nozzle discharge coefficient; and 
     p is the line pressure 
     Assuming the prior art spray heads  68  are spaced ten feet apart, each spray head  68  is responsible for about one hundred square feet of area and the applied water density onto the storage items  54  per spray head  68  will be in the order of about 1.21 gallons/square foot. In contrast, the system  20  of the present invention may be fitted, for example, with supply lines  30  that carry 35 psi water pressure and spray heads  32  having a k-factor of 14. At these specifications, water distribution from each spray head  32  will be on the order of about 83 gpm. However, if the coverage areas  64  for the sprinkler heads  32  are defined by W 2  at four feet and L 2  at fourteen feet, the applied water density per spray head  32  onto the storage items  54  will be in the order of about 1.48 gallons/square foot. In other words, the present invention contemplates applying more gallons per square foot through each spray head  32  than is achieved by a typical prior art ESFR type spray head  68  of a larger k-factor and using higher line pressures. 
     Of course, the critical objective is to arrest growth of a fire at the earliest possible moment. When the initial sprinkler head  68  of the prior art activates, only the 1.21 gallons/square foot is applied. And with spray heads  68  set the typical ten feet apart, it may take several precious moments for additional spray heads  68  to activate. In contrast, the spray heads  32  of the present invention are set at a much closer spacing S, which spacing is further reduced to S/2 (or other fraction) by the novel stagger arrangement, so that more sprinkler heads  32  will be activated more quickly with respective coverage areas being more accurately distributed toward the fire plume. As a result, more water is directed at the fire more quickly than prior art systems. 
     That is to say, heat from a fire plume will initially activate more adjacent sprinkler heads  32  due to the close and stagger spacing features of this invention. Because of the directional, non-circular projection  64  of water spray from activated spray heads  32 , it is expected that a majority of discharged water will be directed toward the fire. As a result, water usage is reduced (compared to the prior art) and the potential for collateral water damage is similarly reduced. Importantly also, a maximum discharge of water is directed at the nascent fire, thereby increasing the likelihood that the fire will be rapidly suppressed. That is to say, in comparison with the prior art, less pressure robbing water is wasted spraying away from the fire and causing collateral water damage to otherwise unaffected storage items  54 . More water is thus available to apply directly into the flues  60 ,  62  with an increased opportunity to control the fire before it has a chance to spread. 
     Benefits of this present invention are many. The blocking surfaces enable the use of side-discharge type sprinklers (special application types listed for the given fire scenario) that can be supplied from any reputable manufacturer, or more preferably the unique sprinkler heads  32  described above. Increased water density can be provided compared with standard, vertically oriented sprinklers  68 . Less water damage might occur in cases where only one sprinkler  32  is activated. And the cost of installation is predicted to be less than that of prior art ESFR systems. 
     The claim of increased water density is accomplished by the ability of this present invention to utilize side-discharge type sprinklers  32  that have the ability to more accurately distribute water toward underlying storage items  54 . The claim of reduced installation cost results from the use of one common supply line  30  per bay area (as compared with two supply lines according to prior art techniques like that taught by U.S. Pat. No. 7,331,399) and also from the potential to separate supply lines  30  a relatively large distance apart (e.g., twenty-five feet) due to the long, narrow and staggered coverage areas of this present invention. In particular, the non-circular coverage area  64  of each spray head  32  has a major diameter L 2  and a smaller minor diameter W 2  that penetrates into the flues  60 ,  62 . The narrow width measure W 2  allows spray heads  32  to be stationed closer together along a common supply line  30 , which in turn increases chances that multiple spray heads  32  will be activated and thereby apply more water into the flues  60 ,  62  where a fire plume is growing. Furthermore, water droplet size and water velocity will be increased due to the added water pressure and volume, which large droplet size helps to force more water into the flues  60 ,  62  against a counter-flow of heat from the fire. 
     The staggered, interlaced non-circular coverage areas  64  of the fire suppression system  20  will discharge water onto the storage items  54  with a high degree of hydraulic efficiency. Through large scale fire tests, where fire suppressing systems and fire sprinkler components are evaluated in a scientific setting, fire control has been proven to be most effective by maximizing the following system variables: water discharge velocity, k factor and water droplet size. Fire control is typically improved by: greater water velocity, higher k factor and/or larger water droplet size. The elongated nature of each coverage area  64 , where the major diameter (L 2 ) is significantly greater than the minor diameter (W 2 ), produces a pattern that more closely mimics a fire hose stream projected at the fire plume. This, in turn, produces larger water droplet size and increases water discharge velocity, while operating at less pressure and volume. Larger water droplets are beneficial because they are less sensitive to the heat rising through the flues  60 ,  62 . That is, larger droplets better penetrate through the flues  60 ,  62  to reach the fire. Likewise, higher velocity water spray coupled with greater water density also penetrates the narrow flues  60 ,  62  as compared with a slower moving, lower density water spray as in prior art systems. 
     The relatively narrow widths W 2  (minor diameters) of the coverage areas  64  advantageously enables relatively close spacing (S) of the fire sprinklers  32  along the supply line  30 . This close spacing (S) of heads  32  along the same side of the same supply line  30  provides numerous key benefits, perhaps chief among which is an improved ability to penetrate the fire flues  60 ,  62 . The unique opposite-facing design utilizing side-discharge style fire sprinklers  32  enables a more precise aim directly into the fire flues  60 ,  62  thus resulting in a more efficient fire suppression system with the sprayed water in large quantities going where it is most needed. Furthermore, the close spacing interval (S) between sprinkler heads  32  along the same side of the same supply line  30  encourages a condition where more sprinkler heads  32  in the vicinity of a fire are activated rather than fewer. Multiple activated spray heads  32  will have a greater chance of avoiding obstructions and a greater chance of penetrating the fire flues  60 ,  62  because of the tighter spacing. That is to say, because two or three spray heads  32  are more likely to be initially activated when in the past only one spray head is initially activated, any physical obstructions—like low beams  24 , structural columns, equipment or atypically large objects—will not be as likely to block the initial water spray in cases whether the obstruction is between one spray head  32  and the fire. Not to mention, greater distance between adjacent supply lines  30  improves the probability that each supply line  30  can be placed in its own bay between adjacent beams  24  as shown in  FIGS. 3 and 4  where they will not be as susceptible to blockage by low-hanging beams  24 . 
     Furthermore, multiple activated spray heads  32  that discharge long, narrow streams of water like a firehose will better attack a fire in the deep interior regions of stacked storage items  54  via the only direct avenues—the flues  60 ,  62 . Even using spray heads  32  with a smaller k-factor fed by lower line pressure, it was shown (above) that larger water distributions (gallons/sq. foot) are possible because the coverage areas  64  are smaller by comparison to prior art ESFR systems. The long, narrow coverage areas  64  are not only accurately aimed toward a fire, but also naturally produce larger water droplets via the design of the deflector which effectively produces an outflow like a hose stream. As a result, water is delivered in a greater density where it is needed the most—into the flues  60 ,  62 . This hose stream effect also works as a fire stop because the water and the droplet sizes are denser. This invention, which may be characterized as a “spot density theory,” goes against the way conventional heads  68  are built, which is on the basis of density (volume/area). Those of skill in the art will acknowledge that there are many shortcomings of the prior art paradigms which place a high premium on density—that is, on blanketing the entire footprint of the storage area with a balanced density of water. In contrast, the spot density theory advanced here allows an early onset fire to be quickly blocked from growing by the hose stream coverage area(s)  64  produced by one or more activated spray heads  32  of this invention. Accordingly, early stage fire suppression success rates will increase based on the principles of this invention. 
       FIG. 10  describes an alternative embodiment wherein the supply line  30  is composed of multiple short sections joined end-to-end by couplings  72 . The couplings  72  may be any commercially available type, such as the grooved pipe joining technology marketed by the Victaulic Company of Easton, PA to name but one possible source. Alluding back to  FIG. 4 , where by phantom lines it was described that a sprinkler  32  may be skewed relative to horizontal as an alternative to adjusting its deflector in order to achieve a desire placement of the coverage area  64 ,  FIG. 10  represents a method by which adjustment can be accomplished after placement of the sprinkler  32  and without altering its deflectors. In the Applicant&#39;s co-pending US Publication No. 2015/0034341, attention is given to the concept of configuring and arranging the coverage areas  64  relative to the overall height and location of the storage items  54  so that, at all stages of a fire but particularly at the initial stages, a maximum amount of water is applied to the flues  60 ,  62  laying directly above the fire so that very little spray is wasted dousing nearby (non-burning) storage items. For all of the reasons therein described, it is desirable to install the present fire suppression system  20  so that the coverage areas  62  are matched to the height and location of the nearby storage items  54 . However, over time the owner of a warehouse is likely to change the height and/or location of the storage items  54 , such that the alignment of coverage areas  64  becomes outdated. By loosening the couplings  72  at each end of a section of supply line  30 , the supply line  30  can be rotated and with it the sprinkler head  32  carried thereon. By careful attention, the coverage area  64  of each spray head  32  can be adjusted whenever there is a change in the height and/or location of the storage items  54  in order to achieve the benefits and objectives explained in US Publication No. 2015/0034341. 
     The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment or can supplement other embodiments unless otherwise indicated by the drawings or this specification.