Patent Description:
German Patent document <CIT> is directed to a sprinkler fire protection system using nozzles for protection of a ceiling cavity, a floor cavity and cable ducts of a building, such as for example, as constructed in theater auditoriums or airport waiting rooms. <CIT> is directed to a method of fire protection of another enclosed space. More specifically <CIT> is directed to a method of fighting a fire in a narrow space, such as an engine room of a ship, using fog-form sprays of an extinguishing medium from nozzles spaced along the narrow space. Another type of building or occupancy in which fire protection systems are provided in interstitial spaces are in data centers. Generally, a data center consists of an equipment room, utilities, and support infrastructure including, for example, air cooling or handling equipment and associated electrical and data cable. Industry accepted recommendations for the protection of data centers are provided in FM Global publication "Property Loss Prevention Data Sheet <NUM>-<NUM>: Data Centers and Related Facilities" (Jul. The loss prevention recommendations include protection recommendations for data centers using water mist systems. More specifically, Data Sheet <NUM>-<NUM> provides data center protection recommendations using an automatic water mist system FM approved for protection of light hazard occupancies. According to the FM recommendations, use of the water mist systems is subject to certain restrictions or limitations including: (i) the water mist system must be a wet system, i.e., a system in which the automatic nozzles are attached to a piping system containing water and connected to a supply so that water discharges immediately from nozzle operated by the heat from a fire; (ii) the data center to be protected must use non-fire-propagating cables in its cable trays; and (iii) the ventilation or air handling systems of the data center are to be interlocked with the water mist system to shut down upon actuation of the water mist fire protection system.

For data center operations it is desirable to run its ventilation systems independent of or without the restrictions of fire protection. Data center equipment rooms can be very large having square footage equal to one or more football fields. For such data centers, shutting down the ventilation system upon fire protection system operation can be an impediment to the data center operations particularly where any indication of a fire is limited to a small area. Accordingly, it would be desirable to have water mist fire protection systems for data centers in which the ventilation or cooling systems can provide for continuous cooling during fire protection operation. Additionally, it would be desirable to have water mist fire protection for propagating and non-propagating cable to provide additional flexibility in the data center construction and operation. Moreover, it would be desirable to have water mist fire protection for a data center that can be configured as a dry pipe or preaction system to keep water out of the system piping in an unactuated state of the water mist system.

Criteria for FM Approval of water mist systems is provided in FM Approvals LLC publication "Approval Standard for Water Mist Systems: Class Number <NUM>" (Nov. In October <NUM>, FM Approvals made a conference paper presentation at the International Water Mist Association (IWMA) Conference in Istanbul, Turkey entitled "Planned Updates to FM Approval Standard Class <NUM>, Water Mist Systems, for <NUM> Revision. " In the presentation, it was noted that the Class <NUM> Approval Standard does not evaluate the aforementioned Data Sheet <NUM>-<NUM> restrictions. Accordingly, FM Approval set forth in its presentation the objectives for evaluating water mist systems in data center protection: i) to evaluate specific fire load, e.g., cables for data processing equipment room; (ii) to evaluate forced ventilation; and (iii) to evaluate water delivery time delay including interlocked systems. The IWMA presentation outlined fire test protocols and criteria for the protection of data centers for above and below a raised floor without the recommendation restrictions. A copy of the FM Approval conference paper is available at http://iwma. net/fileadmin/user_upload/IWMC_2014/FM_Carpenter_Jon_IWMC_2014.

Accordingly in <NUM>, work was ongoing to enable fire testing of water mist systems for data centers without the FM recommendation restrictions. However, the <NUM> conference paper does not identify specific nozzles for use in the proposed fire testing, it does not identify specific nozzle spacing or operational parameters, nor does the paper outline the manner in which nozzles can be identified for use the proposed fire test or in an actual data center environment without the system restrictions. At that time, there remained a need for a system solution which identified nozzles and their installation parameters to overcome the system restrictions of Data Sheet <NUM>-<NUM>.

The invention provides a water mist fire protection system according to claim <NUM>, and a method water mist fire protection of a data centre according to claim <NUM>. Preferred embodiments of water mist fire protection system and method are provided for in the dependent claims.

The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments of the invention and, together with the general description given above and the detailed description given below, serve to explain the features of the exemplary embodiments of the invention.

Shown in <FIG> are various views of a preferred embodiment of a water mist fire protection system <NUM> for protection of a data center <NUM>. The exemplary data center <NUM> can be defined by a deck <NUM>, a raised floor <NUM> disposed above the deck <NUM> defining an interstitial space IS in between. For the preferred fire protections systems <NUM> described herein, the raised floor <NUM> is preferably disposed above the deck <NUM> at a distance or height HI of no more than a maximum distance of <NUM> ft. (<NUM>,<NUM>) above the deck <NUM>. The data center <NUM> includes a ceiling and more preferably a suspended ceiling <NUM> disposed above the raised floor <NUM>. For preferred embodiments of fire protection systems <NUM> described herein, the ceiling <NUM> is preferably located at a distance or height H2 of no more than a maximum distance of <NUM> ft. (<NUM>,<NUM>) above the raised floor <NUM>.

The representative data center <NUM> is configured for housing or storing one or more server cabinets <NUM> along with associated supporting equipment such as for example, cables, cable trays and cooling equipment. For example, one or more above-the-floor elongate cable trays IS (15a, 15b) can be disposed beneath the ceiling <NUM> with the tops of the trays at a distance or clearance of no less than a preferred minimum <NUM> ft. (<NUM>,<NUM>) below the ceiling; and one or more below-the-floor elongate cable trays <NUM> can be disposed in the interstitial space IS between the floor <NUM> and the deck <NUM> with the below-the-floor cable tray(s) located beneath the floor at preferred distance or clearance of no less than of <NUM> in. (<NUM>) from the floor <NUM>. The cable trays <NUM>, <NUM> may be alternatively respectively located closer to the ceiling and floor provided the fire protection system <NUM> can effectively address a fire in a manner as described herein. The cable trays <NUM>, <NUM> can carry fire-propagating and non-fire propagating cable for use in the data center <NUM>. Unlike fire protection systems for data centers constructed under existing industry accepted standards or recommendations, the preferred embodiments of the fire protection system <NUM> can provide for effective fire protection of either type of cable.

The data center <NUM> can also include a ventilation system <NUM> along with associated equipment for providing cool air CA in the interstitial space S between the floor <NUM> and deck <NUM> and throughout the data center <NUM> for cooling the equipment stored therein. Cool air CA can be delivered into the storage space of the data center <NUM> by upward flow through one or more openings in the raised floor <NUM>, for example, through one or more floor grates <NUM> or grated regions installed throughout and/or about the raised floor <NUM>. Heated air HA coming off of the aisles between the cabinets <NUM> can be returned or pulled back to the ventilation system <NUM>.

A preferred embodiment of the system <NUM> includes a plurality of automatic water mist nozzles <NUM> for receipt of water delivered at a desired working pressure in which each nozzle preferably has a diffuser 102a for generating and dispersing a water mist to effectively address a fire. A network of pipes <NUM> interconnect the plurality of nozzles <NUM> to one another and an appropriate water source or supply FL to provide each nozzle with the water at its working pressure. The piping can be constructed from any material suitable for water mist systems including for example, stainless steel piping, CPVC piping and/or internally galvanized piping. The water supply or source FL can be for example, a connection off of municipal water supply system, and more preferably is capable of supplying <NUM> minutes of water to the most remote, more particularly most hydraulically remote eighteen nozzles <NUM> in the system <NUM>.

As a water mist fire protection system, the system <NUM> protects the data center <NUM> and equipment stored therein by addressing a fire and more preferably controlling Class A fires. The system <NUM> can effectively address a fire by one or more of the following: (i) extracting heat from the fire as the water is converted into vapor and the fuel of the fire is cooled; (ii) reducing oxygen levels by water vapor displacement of oxygen near the fire; directly impinging wetting and cooling of the combustibles within the data center <NUM>; and/or (iv) enveloping the protected area to pre-wet adjacent combustibles, cool gases and other fuels in the area as well as block the transfer of radiant heat to adjacent combustibles.

Moreover, operation of the preferred embodiments of the system <NUM> described herein preferably provide effective water mist fire protection to address a fire with or during continuous or simultaneous operation of the ventilation system <NUM>. Thus, the preferred water mist fire protection system <NUM> does not require that the ventilation system <NUM> be interlocked such that the ventilation system shuts off during operation of the fire protection system <NUM>. Unlike prior known systems constructed under existing industry standards or recommendations, cooling air CA can remain circulating during operation of the fire protection system <NUM>. In a preferred method of addressing a fire in the data center, the preferred fire protection system <NUM> addresses the fire in the data center <NUM> by generating a water mist from a plurality of interconnected water mist nozzles <NUM> disposed either above or beneath the raised floor <NUM> in response to the fire while operation of the ventilation system <NUM> is maintained during the water mist generation. More particularly, the system <NUM> and its method of addressing a fire preferably provides for effective fire protection with a water mist in the presence of the forced and more preferably continuous air flow CA, HA from the ventilation system.

By using automatic or sealed, thermally responsive nozzles <NUM>, preferred embodiments of the system <NUM> can be configured for operation as a wet pipe system, in which the piping <NUM> interconnecting the nozzles is filled with water up to the internal seal of the nozzle <NUM> in an unactuated state of the system <NUM>. Upon thermal actuation of one or more nozzles <NUM>, water is immediately discharged for impact against the nozzle diffuser 102a to generate the water mist. However unlike previously known fire protection systems for data centers constructed under the industry standards and recommendations, alternative embodiments of the system <NUM> can be configured as either a dry pipe or preaction system in which the interconnecting pipes <NUM> are maintained dry in an unactuated state of the system. Thus, the system <NUM> can include a fluid control valve <NUM> to control the flow and delivery of water to the nozzles <NUM> upon thermal actuation of one or more nozzles <NUM>. In an alternate preferred operation of the system <NUM> as a preaction system, a fire detection signal is generated in response to a fire and the fluid control valve <NUM> is operated in response to the detection signal to fill the network of interconnecting pipes <NUM> with water before thermal actuation of one or more automatic water mist nozzles <NUM>. Upon thermal actuation of one or more nozzles <NUM>, water is discharged for impact against the diffuser 102a of the actuated nozzles and a water mist is generated to address the fire.

Accordingly, preferred embodiments of the system <NUM> can further include the fluid control valve <NUM> for connecting the network of pipes <NUM> to the water supply FL and more particularly control the flow and pressure of fluid delivered to the nozzles. The fluid control valve <NUM> is preferably electrically operated and controlled by a controller <NUM>. Thus the controller <NUM> is coupled to the fluid control valve <NUM> and generates an appropriate control signal to open the valve <NUM> to permit the flow of water from the supply FL out the fluid control valve <NUM>, through the network of pipes <NUM> for delivery to the nozzles <NUM> of the system <NUM>. The controller <NUM> preferably generates the control signal to operate the valve <NUM> in response to a detection signal indicating a fire. To detect a fire, the system <NUM> preferably includes one or more detectors <NUM> for detecting a fire within the data center <NUM> and generating a detection signal DS indicating a fire. The detector <NUM> can be any type of sensor capable of detecting the start or presence of a fire, such as for example a thermal, smoke or particulate sensor and generating an appropriate detection signal DS. The controller <NUM> is appropriately coupled to the controller <NUM> wired or wirelessly to receive the detection signal DS and generate the appropriate control signal CS for operation of the fluid control valve <NUM> in a preferably single interlock manner. As a dry pipe or preaction system, the preferred system <NUM> experiences a fluid delivery delay at full fluid pressurization from the water supply FL to the one or more actuated nozzles <NUM>. The controller <NUM>, its operation of the valve <NUM>, and the network of pipes preferably define a fluid delivery delay time of no more than sixty seconds (<NUM> sec. ) and more preferably no more than thirty seconds (<NUM> sec. Exemplary embodiments of the fluid control valve, controller, the detector and a single interlock configuration are shown and described in greater detail in Tyco Fire Products LP technical data sheets TFP1420 entitled "Preaction System with DV-<NUM> Deluge Valve Single Interlock, Supervised -- Electric Actuation <NUM>-<NUM>/<NUM> thru <NUM> inch (DN40 thru DN200)" (Oct. <NUM>) and TFP2270, entitled "AQUAMIST Mist Control Center (MCC) Pump Skid Unit (Oct. Each of TFP1420 and TFP2270 is incorporated by reference in its entirety.

The nozzles <NUM> are located and installed to provide or define one or more fire protection configurations of particularized regions of the data center including: an above-the-floor configuration, a below-the-floor configuration; and/or a local application configuration to provide localized water mist fire protection to the one or more cable trays <NUM> disposed beneath the floor <NUM>. Moreover, preferred nozzles have been identified for use in the preferred system <NUM> that effectively provide for water mist fire protection for data centers without the installation and construction requirements and limitations under the industry accepted recommendations and standards previously described such as, for example, (i) wet only system type fire protection; (ii) ventilations system interlocking; and (iii) the use of non-propagating cables in the cable trays. Accordingly, preferred methods and systems <NUM> of water mist fire protection of a data center provide for locating a plurality of automatic water mist nozzles <NUM> at least one of above or below the raised floor <NUM> and interconnecting the automatic water mist nozzles to a water supply for generating the water mist to address a fire in the presence of a continuous flow of air from the ventilation system <NUM> for the protection of the data center including non-propagating and propagating cable. Additionally, the preferred systems and methods provide for a water mist fire protection system that can be either a dry pipe system or a preaction system.

Referring to <FIG>, <FIG>, schematically shown are a plurality of preferred nozzles <NUM>, each having a diffuser 202a, located below the raised floor <NUM> to define a preferred below-the-floor configuration and localized application configuration in the interstitial space S for the protection of the data center <NUM>. The plurality of located nozzles <NUM> are shown located to protect propagating cable or non-propagating cable in at least one below-the-floor cable tray <NUM>. In one preferred embodiment of the below-the-floor configuration, for example as seen in <FIG>, the preferred nozzles <NUM> are located and installed below the raised floor in an upright configuration. Once installed, the upright nozzles <NUM> and their diffusers 202a preferably define a minimum diffuser-to-floor distance or clearance between the floor and the diffuser preferably of no more than a maximum of <NUM> in. (<NUM>,<NUM>. Where a preferred upright nozzle <NUM> is located beneath a floor grate region <NUM>, the nozzle is inset preferably no further than a maximum <NUM> in. ) from a lateral or elongate edge of the floor grate <NUM>. The nozzles <NUM> define a preferred a nozzle-to-nozzle spacing S x S ranging from a minimum <NUM> ft. (<NUM>,<NUM> x <NUM>,<NUM>) to a maximum <NUM> ft. × <NUM> ft. (<NUM>,<NUM> x <NUM>,<NUM>), and no more than <NUM> ft. (<NUM>,<NUM>. ) from an elongated edge 17a of any cable tray <NUM> beneath the floor regardless of whether the cable tray is spaced from one or more floor grates 20a, 20b, as seen in <FIG>; or beneath a floor grate <NUM> as seen, for example, in <FIG>. The preferred nozzles <NUM> define a preferred working nozzle pressure of <NUM> to <NUM> psi. (<NUM>,<NUM> to <NUM>,<NUM> bar). Hydraulically, the preferred below-the-floor nozzles <NUM> can be hydraulically designed to the most hydraulically demanding area in the system <NUM> or alternatively hydraulically designed to an area-of-coverage design defined by a preferred minimum six nozzles.

Additionally or alternatively, the one or more of the preferably upright nozzles <NUM> located below the floor <NUM> can provide for localized application of water mist in the protection of the below-the-floor cable tray <NUM> and the cable housed therein as seen schematically, for example, in FIG. In particular, the group of water mist nozzles are installed in an upright configuration with a nozzle-to-nozzle spacing S x S ranging from a minimum <NUM> ft. × <NUM> ft. (<NUM>,<NUM> x <NUM>,<NUM>) to <NUM> ft. × <NUM> ft. (<NUM>,<NUM> x <NUM>,<NUM>) with each of the nozzles <NUM> including a diffuser 202a at a diffuser-to-floor distance being no more than a maximum of <NUM> in. In the preferred localized application, the preferred nozzles <NUM> are preferably spaced no more than <NUM> in. ) from an elongated edge 17a of the cable tray, and are preferably not located over top of the cable tray <NUM>. The preferred localized application configuration is preferably hydraulically configured to a minimum four nozzles per design area. The preferred localized application configuration can provide for effective water mist fire protection of the cable tray <NUM> without having to install a complete grid for just the cable tray <NUM>.

Shown in <FIG> are elevation and cross-sectional views of a preferred automatic nozzle <NUM> for use in the below-the-floor and localized applications configurations of the preferred methods and systems described herein. The preferred nozzle <NUM> generally includes a frame body <NUM> for coupling to a branch line of the interconnecting piping network <NUM>, an internal seal assembly <NUM>, a thermally responsive trigger <NUM>, and a preferred diffuser 202a for generating the water mist to address a fire. The frame body <NUM> includes an inlet 210a, an outlet 210b with a passageway 210c extending between the inlet 210a and the outlet 210b. The nozzle <NUM> define a discharge coefficient of a preferably nominal K-Factor. Preferably, the nozzle <NUM> defines a nominal K-factor of less than <NUM> gpm/psi½ (<NUM> lpm/(bar)<NUM>/<NUM> and is more preferably <NUM> gpm/psi½ (<NUM> lpm/(bar)<NUM>/<NUM>.

The frame body <NUM> further preferably includes a pair of frame arms 210d diametrically opposed about the outlet 210b. The diffuser 202a is supported from and spaced from the outlet 210b by the frame arms 210d. Once coupled to a water supply pipe <NUM>, the preferred diffuser 202a and frame body <NUM> defines a preferred upright orientation. The frame arms 210d preferably converge toward an apex or knuckle 210e axially aligned with the passageway and outlet 210c, 210b. The diffuser 202a is preferably engaged with and centered with the knuckle 210e. As seen in <FIG>, the preferred diffuser 202a is a preferably planar member with a central portion 203a axially aligned and centered with the passageway 210c and an outer peripheral portion 203b circumscribed about the central portion 203a to define a substantially circular periphery with a preferred diameter DIAl of <NUM> inches (<NUM>,<NUM>). The preferred peripheral portion 203b includes a plurality of spaced apart tines (203c1, 203c2, 203c3,. 203ci) to define a plurality of open ended slots 203d formed therebetween extending radially inward preferably at equal distance toward the central portion 203a.

In an unactuated state of the nozzle <NUM>, the sealing assembly <NUM> is supported in the outlet 210b by the thermally responsive trigger <NUM> which is preferably embodied as a thermally responsive glass bulb <NUM>. The glass bulb <NUM> is supported against the sealing assembly <NUM> by the frame body <NUM> by a load or compression screw <NUM>. In its thermal response to the fire, at a desired activation time, the bulb <NUM> ruptures thereby releasing its support from the sealing assembly which is preferably ejected from the outlet by an ejection spring <NUM>. The thermally responsive element <NUM> can have a temperature rating ranging between about <NUM>° F <NUM>. to about <NUM>° F185°C. , preferably <NUM>°F, <NUM>°F, <NUM>°F, <NUM>°F, <NUM>°F, or <NUM>°F (<NUM>. °C, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>) and more preferably is any one of <NUM>° F orl55° F <NUM> or <NUM>. The bulb <NUM> is preferably configured with a Response Time Index (RTI) of <NUM> (meters-seconds) <NUM>/<NUM> or less and preferably any one of <NUM> or <NUM> (meters-seconds) <NUM>/<NUM> so as to have a fast response, and more preferably, the bulb <NUM> is such that the nozzle <NUM> can be a quick response device.

Disposed within the inlet 210a is a strainer <NUM> to filter out debris which may clog or damage the internal passageway of the nozzle <NUM>. Preferably included within the passageway 210c is an orifice insert <NUM> preferably supported by a shelf or shoulder formed along the interior walls of the passageway 210c. The orifice insert <NUM> includes an interior through bore <NUM> through which incoming fluid flows. The orifice insert <NUM> and through bore <NUM> define the preferred K-factor of less than <NUM> gpm/(psi) <NUM>/<NUM> (<NUM> lmp/bar<NUM>/<NUM>), preferably in the range from about <NUM> to <NUM> gpm/(psi) <NUM>/<NUM> (<NUM> to <NUM> lmp/bar<NUM>/<NUM>), and more preferably is <NUM> gpm/(psi) <NUM>/<NUM> (<NUM> lpm/bar <NUM>/<NUM>). Passageways defining larger or smaller K-factors can be employed provided the resulting water mist is effective in addressing a fire in the presence of an airflow and/or can be used in the protection of propagating cable. Upon thermal actuation of the nozzle <NUM>, water passes through the orifice insert <NUM> and its through bore <NUM> for discharge from the outlet 210b in a preferably upward direction to impact the diffuser 202a for generation of the water mist to address the fire in a manner as described. A commercial embodiment of the preferred nozzle <NUM> is shown and described in Tyco Fire Products LP technical data sheet TFP2201, entitled "Ultra Low Flow AQUAMIST Nozzles Type ULF AM30 Automatic (Closed)" (May <NUM>).

Applicant has developed a preferred method and criteria for the identification of the nozzles for preferred use in the system <NUM> and its embodiments described herein. Moreover, the preferred methods can be used for identifying nozzles to use in a fire test for water mist systems such as for example water mist test protocols and criteria outlined and developed by FM Approval in the planned update to Standard Class <NUM>. The preferred method of identifying nozzles includes a distribution analysis in a below-the-floor arrangement. Shown in <FIG> are schematic views of a test set-up <NUM> for evaluating the water mist patterns of nozzles for use in the system <NUM>. The test set-up <NUM> includes a deck <NUM> and raised floor <NUM> spaced from the deck <NUM> by a clearance distance of three feet (3ft. ) (<NUM>) Mounted between the deck and floor <NUM>, <NUM> is a first cable tray 517a, and a second cable tray 517b. The top of the first cable tray 517a is located at a preferred distance of twelve inches from the raised floor <NUM> and the top of the second cable tray 517b is located at a preferred distance of twenty-four inches from the raised floor <NUM>. Located over the first cable tray 517a and beneath the raised floor <NUM> at diffuser-to-floor clearance distance of four inches (<NUM> in. ) are two preferred upright test nozzles <NUM>, <NUM> such as previously described. Each nozzle is spaced inset from the wall <NUM> by a distance of six inches (<NUM> in. The two nozzles <NUM>, <NUM> are spaced apart at a distance X of four meters (<NUM>,<NUM>)(<NUM> ft.

Located on the deck <NUM> are a group of water collection pans <NUM> that included pans disposed along the wall <NUM> and centered between the two preferred nozzles <NUM>, <NUM>. The tops of the pans measure about <NUM> ft. Two sets of discharge tests were conducted. In the first set of tests, water was delivered at a pressure of <NUM> psi. to the two nozzles <NUM>, <NUM> having an orifice insert defining a K-factnr of <NUM> gpm/(psi) <NUM>/<NUM> (<NUM> lmp/bar<NUM>/<NUM>) to provide for a flow of <NUM> gallons per minute (GPM) (<NUM>. Water was discharged for a duration of <NUM> minutes. In the second set of tests, water was delivered at a pressure of <NUM> psi. (<NUM> bar<NUM>/<NUM>) to the two nozzles <NUM>, <NUM> with the orifice insert defining a larger K-factor of <NUM> gpm/(psi) <NUM>/<NUM> (<NUM> lmp/bar<NUM>/<NUM>) to provide for a flow of <NUM> gallons per minute (GPM) ((<NUM> lpm). Water was discharged again for a duration of four minutes (<NUM>. Each of the collection pans <NUM> were appropriately weighed after the discharge period to determine the distribution weight rate in the pan. An array of eight collection pans <NUM> disposed about the midline (y-Y) between the two nozzles <NUM>, <NUM> were evaluated. Summarized in the tables below are the average measurements of the distribution weight rates in each of the eight collection pans in units of ounces per minute (oz.

(K-factor <NUM>,<NUM>US is <NUM>,<NUM><NUM> * min-<NUM> * bar-<NUM>/<NUM> and
K-factor <NUM>,<NUM>US is <NUM>,<NUM> * min-<NUM> * bar-<NUM>/<NUM>; further the conversion rate for
oz/min is: <NUM> ouncesUS/min = <NUM><NUM>/min ).

By looking at the variations between particular rows it was determined that the preferred nozzle <NUM> and its diffuser could provide for a water mist to effectively address a fire and protect a data center in a manner described herein. In particular, the variability in the subject array of eight collection pans from the wall <NUM> to four feet (<NUM> ft. ) (<NUM>) inset was within acceptable ranges. It was noted that a decrease in weight rate from the first row to the second row was no more than <NUM>% and is preferably less than about <NUM>%. It was further noted that the change from the second row of collection pans to either the third or fourth pan was about <NUM>-<NUM>% and is preferably in the range of <NUM>-<NUM>%. Although the preferred distribution testing is conducted without forced ventilation or continuous air flow and without a fluid delivery delay, the resultant rates of weight distribution indicates the suitability of a nozzle to generate an effective mist for fire protection in the presence of forced ventilation or when subject to a fluid delivery delay. Accordingly, water mist distributions patterns have been identified which overcome the limitations under the current standards and recommendations. Moreover, a method of water mist tire protection is provided that includes obtaining preferred automatic mist nozzles; and distributing the nozzles for installation above or below the raised floor to address a fire with a mist in the presence of the continuous flow of air, protect fire propagating cable or provide for one of dry pipe or preaction fire protection. Obtaining a nozzle can include identifying a nozzle for use in a preferred water mist system using a preferred water distribution system. Alternatively, nozzles can be obtained by procurement or manufacture which can be identified for use in a water mist fire protection system as described. Distributing the nozzle can include selling, shipping or otherwise providing the obtained nozzles for installation in a preferred water mist fire protection system.

Shown in <FIG> are elevation and cross-sectional views of another preferred automatic nozzle <NUM> identified for use in the below-the-floor configurations of the preferred methods and systems described herein and more preferably for use in the local application for protection of below-the-floor cable trays <NUM>. The preferred nozzle <NUM> generally includes a frame body <NUM> similar to that shown in <FIG>. The frame <NUM> is configured for coupling to a branch line of the interconnecting piping network <NUM> in a preferably pendent configuration, an internal seal assembly <NUM>, a thermally responsive trigger <NUM>, and a preferred diffuser <NUM> for generating a water mist to address fire. The frame body <NUM> includes an inlet 310a, an outlet 310b with a passageway 310c extending between the inlet 310a and the outlet 310b. The outlet 310b and passageway 310c define a discharge coefficient of a preferably nominal K-factor. Preferably, the nozzle <NUM> defines a nominal K-factor of less than <NUM> gpm/psi½ (<NUM> lmp/bar<NUM>/<NUM>) and is more preferably <NUM> gpm/psi½ (<NUM> lmp/bar<NUM>/<NUM>).

The frame body <NUM> further preferably includes a pair of frame arms 310d diametrically opposed about the outlet 310b. The diffuser <NUM> is supported from and spaced from the outlet 310b by the frame arms 310d. Once coupled to a fluid supply pipe <NUM>, the preferred diffuser <NUM> and frame body <NUM> defines a preferred pendent orientation. The frame arms 310d preferably converge toward an apex or knuckle 310e axially aligned with the passageway and outlet 310c, 310b. The diffuser <NUM> is preferably engaged with and centered with the knuckle 310e.

In an unactuated state of the nozzle <NUM>, the sealing assembly <NUM> is supported in the outlet 310b by the thermally responsive trigger <NUM> which is preferably embodied as a thermally responsive glass bulb <NUM>. The glass bulb <NUM> is supported against the sealing assembly <NUM> by the frame body <NUM> by a load or compression screw <NUM>. In its thermal response to the fire, at a desired activation time, the bulb <NUM> ruptures thereby releasing its support from the sealing assembly <NUM> which is preferably ejected from the outlet by an ejection spring <NUM>. The thermally responsive element <NUM> can have a temperature rating ranging between about <NUM>° F <NUM> to about <NUM>°F. , <NUM> and more preferably is any one of <NUM>°F, <NUM> <NUM>°F, <NUM>°F, <NUM>°F, <NUM>°F, or <NUM>°F (<NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>). The bulb <NUM> is preferably configured with a Response Time Index (RTI) of <NUM> (meters- seconds) <NUM>/<NUM> or less and preferably any one of <NUM> or <NUM> (meters-seconds) <NUM>/<NUM> so as to have a fast response, and more preferably, the bulb <NUM> is such that the nozzle <NUM> can be a quick response device.

Disposed within the inlet 310a is a strainer <NUM> to filter out debris which may clog or damage the internal passageway of the nozzle <NUM>. Preferably included within the passageway 310c is an orifice insert <NUM> preferably supported by a shelf or shoulder formed along the interior walls of the passageway 310c. The orifice insert <NUM> includes an interior through bore <NUM> through which incoming fluid flows. The orifice insert <NUM> and through bore <NUM> define the preferred K-factor of less than <NUM> gpm/(psi) <NUM>/<NUM> (<NUM> lmp/bar<NUM>/<NUM>), preferably in the range from about <NUM> to <NUM> gpm/(psi) <NUM>/<NUM> (<NUM> to <NUM> lmp/bar<NUM>/<NUM>), and more preferably is <NUM> gpm/(psi) <NUM>/<NUM> (<NUM> lpm/bar <NUM>/<NUM>). Upon thermal actuation of the nozzle <NUM>, water passes throug the orifice insert <NUM> and its through bore <NUM> for discharge from the outlet 310b to impact the diffuser <NUM> for generation of the water mist to address the fire.

As seen in <FIG>, is the preferred diffuser <NUM> of the preferred nozzle <NUM>. In plan, the diffuser <NUM> defines a substantially circular shape with an outer peripheral edge <NUM> formed about a central diffuser axis. The diffuser <NUM> includes a central bore <NUM> for mounting about the frame <NUM>. The diffuser <NUM> is a substantially frustoconical member having an upper surface <NUM> and a lower surface <NUM> that is preferably substantially parallel to the upper surface <NUM>. Preferably, the diffuser element <NUM> includes a substantially planar central base region <NUM> and an outer annular substantially planar region 406c in which each of the central and outer regions of the upper surface <NUM> are disposed orthogonal to the nozzle axis when the diffuser element <NUM> is installed about the frame <NUM>. The outer planar region 406c and its peripheral edge <NUM> define the maximum outer diameter DIA2 of the diffuser <NUM> so as to preferably be <NUM> inches (<NUM>,<NUM>). The diffuser element <NUM> is further preferably formed such that the upper surface <NUM> defines a generally annular intermediate region 406b between the central region 406a and the outer region 406c. The intermediate region 406b preferably defines a truncated cone slanted at a downward angle a, relative to a plane parallel the central and outer planar regions 406a, 406c. The angle a preferably ranges between about e.g. in the range of about <NUM>° to about <NUM>° and is more preferably about <NUM>°.

The surfaces of the diffuser <NUM> further define a plurality of slots and through holes through which fluid flows to form the water mist pattern of the nozzle <NUM>. Preferred embodiments of the nozzle <NUM>, its diffuser <NUM> and water mist pattern are shown and described in <CIT>. A commercial embodiment of the preferred nozzle <NUM> is shown and described in Tyco Fire Products LP technical data sheet TFP2229, entitled "Ultra Low Flow AQUAMIST Nozzles Type ULF AM29 Automatic (Closed)" (May <NUM>). Each of <CIT> and TFP2229 is incorporated by reference in its entirety.

In the preferred diffuser element <NUM>, the plurality of slots preferably includes at least three groups of slots <NUM>, <NUM> and <NUM>. Generally, each of the slots has an initial portion, a terminal portion and an intermediate portion that is continuous and disposed between the initial and terminal portions. The initial portion of the slot is defined by an opening along the peripheral edge <NUM> of the diffuser element <NUM>. The opening forms a pair of spaced apart walls in the diffuser <NUM> that extend inward toward the diffuser central axis so as to define the intermediate portion of the slot. In each of the slots of the diffuser element <NUM>, the pair of walls converge to form the end face of the slot and define the terminal end portion of the slot. The spacing between the walls define the width of the slot. The spacing between the walls of the slot can be constant along the length of the slot or alternatively the spacing between the walls may vary. Moreover, the wall spacing of the slot can vary either continuously along the slot length or vary discretely such that one portion of the slot varies from another portion of the slot, for example, the terminal portion may be wider than the initial or intermediate portion of the slot.

In the preferred embodiment of the diffuser element <NUM>, the groups of slots <NUM>, <NUM>, <NUM> vary with respect to one or more of the slot features such as, for example, slot width, slot length, and/or geometry of any one of the initial, intermediate or terminal portions of the slot. The first group of slots <NUM> in which the opening and wall of the slot are dimensioned to define a preferred constant width along the length of the slot between the initial and intermediate portions of the slot. The terminal portion of the slot defines a slot width greater than the slot width of the initial or intermediate portions of the slot. Within the first group of slots <NUM>, the preferred embodiment of the diffuser element <NUM> includes at least three types of slots 410a, 410b, 410c which vary with respect to one or more of the slot features such as, for example, slot width and/or geometry of any one of the initial, intermediate or terminal portions of the slot. For example, the slot widths the initial and intermediate portions vary from slot type to slot type.

In the second group of slots <NUM>, the slot opening and walls are preferably spaced to define a slot width that is substantially constant along the slot length from the initial portion through the intermediate portion of the slot. The terminal portion and end face of the slot is preferably defined by a radius of curvature whose center is centrally disposed between the two walls of the slot so as to be located along the central axis of the slot. The terminal portion of the slots <NUM> is preferably located such that the slot length of the second group of slots <NUM> is greater than the slot length of the first group of slots <NUM>.

The preferred third group of slots <NUM> has its opening along a peripheral edge <NUM> and preferably located along the end face of the terminal portion of a slot in the first group of slots <NUM>. The walls defining the slot width in the third group preferably diverge away from one another in the inward direction such that the slot width broadens at preferably constant rate from the initial portion through the intermediate portion in the inward direction. The terminal portion and end face of the slot is preferably located more radially inward than the terminal portions of either the first group <NUM> or second group <NUM> of slots. The formation of the diffuser <NUM> can bring the walls at the initial portion of the slots of the third group of slots <NUM> into close contact such that the third group of slots <NUM> act as through holes forming a substantially tear dropped shaped opening in the diffuser element that is completely bound by an effectively continuous wall.

Each group of slots and through holes is preferably symmetrically and equiradially disposed over the diffuser element <NUM>. More specifically, the first type of slots 410a preferably include two pairs of diametrically opposed slots; the second type of slots 410b of the first group <NUM> preferably includes two pairs of diametrically opposed slots disposed slots; each pair disposed on a pair of orthogonal axes preferably located forty-five degrees (<NUM>°) relative to the first type of slots 410a. The third type of slots 410c of the first group <NUM> preferably includes two pairs of diametrically opposed slots; each pair disposed respectively at an angle of about eighteen degrees (<NUM>°) relative to one of the first type of slots 410a. The second group of slots <NUM> preferably includes two pairs of diametrically opposed slots located at an angle of about eighteen degrees relative to the first type of slot such that radially adjacent slots of the third type 410c of the first group <NUM> and the slots of the second group <NUM> are radially spaced by about fifty degrees (<NUM>°). The third group of slots <NUM> preferably includes a pair of diametrically opposed slots preferably axially aligned with one pair of diametrically opposed slots of the first type 410a of the first group <NUM>. More preferably, the slots of the third group <NUM> are centered between slots of the third type 410c of the first group <NUM>.

The diffuser <NUM> also preferably includes a plurality of through holes. More preferably, the diffuser element <NUM> includes a plurality of groups of through holes <NUM>, <NUM> with a geometry that preferably varies group to group. For example, the first group of through holes <NUM> is preferably substantially elliptical in shape and the second group of through holes <NUM> is substantially key-holed shaped. The second group of through holes <NUM> are also preferably elongated so as to have a major axis and a minor axis orthogonal to the major axis. The major axis preferably intersects the central axis of the diffuser <NUM>. The second group of through holes <NUM> are each defined by a first radius and a second radius each having a center disposed along the major axis of the through hole <NUM>. The second radius is preferably smaller than the first radius so that the through hole <NUM> is substantially key holed shape, tapering narrowly in the inward direction.

The first through holes <NUM> preferably includes two pairs of diametrically opposed through holes in which each through hole has its minor axis aligned with the orthogonal central axes of the first type of slots 410a of the first group <NUM>. The second group of through holes <NUM> preferably include two pairs of diametrically opposed through holes in which their major axes are disposed on intersecting axes. More preferably, the second through holes are oriented such their major axes are disposed at a radial angle of about twenty-six degrees to the central axes of the first type of slots 410a of the first group <NUM>.

Referring back to FIG. IF and <FIG>, an alternate installation is provided for localized application of water mist in the protection of the below-the-floor cable tray <NUM> and the cable housed therein. The preferred plurality of nozzles <NUM> of <FIG> are installed in a pendent configuration with a nozzle-to-nozzle spacing ranging from a minimum <NUM> ft. (<NUM>,<NUM> x <NUM>,<NUM>) to a maximum <NUM> ft. x <NUM> ft. (<NUM>,<NUM> an x <NUM>,<NUM>). The preferred nozzles <NUM> define a preferred working nozzle pressure of <NUM> to <NUM> psi. (<NUM>,<NUM> to <NUM>,<NUM> bar). The preferred localized application configuration is preferably hydraulically configured to a minimum four nozzles per design area. The diffuser <NUM> is disposed at a diffuser-to-floor distance of no more than a maximum of <NUM> in. (<NUM>,<NUM>. ) and spaced no more than <NUM> in. (<NUM>) from an elongated edge 17a of at least one below-the-floor cable tray such that the nozzle <NUM> is preferably not directly above the at least one below-the-floor cable tray.

The preferred method and systems of water mist fire protection preferably includes water mist generation from above the floor <NUM>. In one particular preferred embodiment, a plurality of nozzles <NUM>, as seen in <FIG>, are installed above the floor <NUM> and beneath the ceiling <NUM> in a pendent configuration as schematically shown in <FIG>. In a preferred installation, the nozzles <NUM> are located and installed to define a nozzle-to-nozzle spacing ranging from a minimum <NUM> ft. (<NUM>,<NUM> x <NUM>,<NUM>) to <NUM> ft. x <NUM> ft. (<NUM>,<NUM> x <NUM>,<NUM>), each of the pendent nozzles having a diffuser defining a diffuser-to-ceiling distance of <NUM> in. to <NUM> in. (<NUM> to <NUM>). With the preferred nozzles <NUM> define a preferred working nozzle pressure of <NUM> to <NUM> psi. (<NUM>,<NUM> to <NUM>,<NUM> bar); the preferred above-the-floor configuration, the nozzles <NUM> are preferably connected in a grid to define a hydraulic design demand of at least the most remote fourteen (<NUM>) nozzles and more preferably the most remote eighteen (<NUM>) nozzles in the system <NUM>.

Claim 1:
A system, comprising:
a water mist fire protection system (<NUM>);
a deck (<NUM>), a raised floor (<NUM>) disposed above the deck (<NUM>) at no more than a maximum distance of <NUM> ft. (<NUM>) above the deck (<NUM>) to define an interstitial space (IS) therebetween, at least one below-the-floor cable tray (<NUM>) disposed between the floor (<NUM>) and the deck (<NUM>) at a distance of no less than <NUM> in. (<NUM>) from the floor (<NUM>), and a ventilation system (<NUM>) providing a flow of cooling air through the interstitial space (IS),
the water mist fire protection system (<NUM>) comprising:
a plurality of water mist nozzles (<NUM>) disposed beneath the raised floor (<NUM>), each nozzle including a frame body (<NUM>) having an inlet (210a), an outlet (210b) with a passageway (210c) extending between the inlet (210a) and the outlet (210b) to define a nozzle axis, a discharge coefficient of a nominal K-Factor of less than <NUM> gpm/(psi)½ (<NUM> lpm/(bar) ½) and a working pressure, a seal assembly (<NUM>), a thermally responsive trigger (<NUM>) to support the seal assembly in the outlet (210b); and a diffuser (202a) coupled to the frame body (<NUM>) and spaced from the outlet (210b), the plurality of water mist nozzles (<NUM>) are upright and have a nozzle-to-nozzle spacing ranging from a minimum <NUM> x <NUM> (6ft x 6ft) to <NUM> x <NUM> (12ft x 12ft), the diffuser (202a) being at a diffuser-to-floor distance of no more than a maximum of <NUM> (<NUM> in.) and spaced no more than <NUM> (<NUM> in.) from an elongated edge of at least one below-the-floor cable tray (<NUM>) such that the nozzle (<NUM>) is not directly above the at least one below-the-floor cable tray (<NUM>); and
a network of pipes (<NUM>) interconnecting the plurality of nozzles to a water supply (FL) for generating a water mist for effectively addressing a fire,
the water mist effectively addresses the fire in the presence of any one of: (i) continuous flow of air through the interstitial space; (ii) fire-propagating cable in the cable tray; and (iii) a fluid delivery delay from the water supply (FL) to the water mist nozzles (<NUM>) characterized in that: wherein the raised floor (<NUM>) has a floor grate region (<NUM>), at least one of the nozzles (<NUM>) disposed beneath the raised floor (<NUM>) is installed beneath the floor grate region (<NUM>), the at least one nozzle (<NUM>) being no further inset than a maximum <NUM> (<NUM> in.) from a lateral edge of the floor grate region (<NUM>).