Patent Publication Number: US-9849318-B2

Title: Fire suppression system with variable dual use of gas source

Description:
BACKGROUND 
     There are a variety of fire suppression systems. Many utilize sprinkler heads or nozzles mounted near a ceiling in various positions in a room. Some such systems are known as deluge systems. These release a relatively large amount of water responsive to a fire condition to douse a fire and saturate objects in the room to prevent them from igniting. 
     Other sprinkler-based fire suppression systems release a fine mist into a room responsive to a fire condition. One advantage to such systems over deluge systems is that they use less water. On the other hand, some misting systems require relatively high pressure to achieve the desired discharge of fire suppressing fluid. Typical misting systems use pressurized gas to shear the fluid as it is dispersed from the nozzles. 
     Many misting sprinkler fire suppression systems include a pump to achieve the pressures necessary for system operation. Water-based misting systems, for example, require an operating pressure that is higher than the typical pressure available from a municipal water supply. The pump is often one of the most expensive components of the system, which hinders an ability to reduce the cost of the system. Some systems also include pressurized gas tanks that pressurize the fluid lines that deliver the fluid to the sprinkler nozzles. 
     SUMMARY 
     An exemplary fire suppression system includes a sprinkler nozzle. At least one conduit is connected to the nozzle for delivering a fire suppression fluid to the nozzle. The conduit and the nozzle establish a discharge path. A pneumatically driven pump is connected with the conduit for pumping fluid into the conduit. A gas source provides pressurized gas to the pump for driving the pump. The gas source also provides gas to the discharge path for achieving a desired discharge of the fluid from the nozzle. A controller selectively controls at least one of (i) the gas provided to the pump, which controls the fluid pressure in the conduit, or (ii) the gas provided to the nozzle or the conduit, which controls the gas pressure delivered to the nozzle. 
     An exemplary method of operating a fire suppression system includes driving a pneumatically driven pump with pressurized gas from a gas source to cause the pump to deliver a pressurized fluid through a conduit to a nozzle. A desired discharge of the fluid from the nozzle is achieved by providing gas from the gas source to the discharge path established by the conduit and the nozzle. Selectively varying at least one of (i) the gas provided to the pump or (ii) the gas provided to the nozzle controls the discharge from the nozzle. 
     The various features and advantages of disclosed examples will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates selected portions of a fire suppression system designed according to an embodiment of this invention. 
         FIG. 2  schematically illustrates another example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically shows selected portions of a fire suppression system  20 . An example sprinkler nozzle  22  is positioned to discharge a fire suppressing fluid into an area responsive to a fire condition. The nozzle  22  is connected to a conduit  24 . The nozzle  22  and the conduit  24  establish a discharge path. A pump  26  causes fluid from a source  28  to flow through the conduit to the nozzle  22 . In one example the fluid comprises water and the source  28  is a municipal water supply. In another example, the fluid source  28  is a reservoir of a selected fluid such as water. In one example the fluid reservoir is at ambient pressure. 
     The pump  26  in this example is a pneumatically driven hydraulic pump. The pump  26  delivers the fluid (e.g., water) to the nozzle  22  through the conduit  24  when the pump  26  is driven by pressurized gas. The illustrated example includes a pressurized gas source  30  that provides pressurized gas through a supply line  32 . In one example the gas source  30  comprises a rotary compressor. In another example, the gas source  30  comprises at least one pressurized tank. The gas may be air or carbon dioxide or nitrogen for example. 
     One branch  34  of the supply line  32  delivers pressurized gas to the pump  26  to drive the pump  26  for delivering the fluid from the supply  28  to the nozzle  22 . Another branch  36  of the supply line  32  delivers the gas to the discharge path (i.e., at least one of the nozzle  22  or the conduit  24 ) at some point (e.g., upstream of the nozzle  22  or at the nozzle  22 ) to achieve a desired discharge of the fire suppressing fluid from the nozzle  22 . The particular location at which the gas is introduced for achieving the desired discharge will depend on the particular design of the system  20 , the nozzle  22  or both. For example, a system that relies upon mixing gas and liquid upstream of the nozzle  22  will include a branch  36  that provides the pressurized gas into the conduit  24  at a suitable location. Another system that relies upon mixing gas and liquid within the nozzle  22  will include the branch  36  coupled to a suitable inlet of the nozzle  22 . 
     Given this description and a chosen system or nozzle configuration, those skilled in the art will be able to determine the best location for introducing the gas for achieving the desired discharge. 
     One feature of the illustrated example is that the same gas source  30  provides pressurized gas for driving the pump  26  and pressurized gas to achieve the desired discharge from the nozzle  22 . 
     This example eliminates a separate electrical connection for the pump  26 . For systems  20  that include pressurized cylinders as the gas source  30 , no electrical connection is required for the entire system. Another feature of the illustrated example is that it reduces the footprint (or occupied space) of the pump compared to other systems that do not include such a pump. It also utilizes the gas source  30  for the dual purpose of supplying gas to the system  20  to achieve a desired discharge from the nozzle  22  and to drive the pump  26 . This provides a lower cost arrangement for a supply of liquid and gas (e.g., water and air) that provides the desired pressure of each for the system  20 . 
     The illustrated example system  20  includes a controller  40  that controls the operation of regulators  42  and  44 , respectively. The controller  40  selectively varies the pressure or amount of gas that flows to the pump  26  by controlling the regulator  42 . The controller  40  selectively varies the pressure or amount of gas that flows to the nozzle  22  or conduit  24  by controlling the regulator  44 . By controlling at least one of the gases provided to the pump  26  or the gas provided to the nozzle  22 , the discharge from the nozzle can be selectively controlled. 
     In one example, the controller  40  is programmed to selectively vary the gas provided to at least one of the pump  26  or the nozzle  22  over time to achieve different discharges from the nozzle  22 . In one such example, the discharge from the nozzle  22  depends, at least in part, on the ratio of the gas to the liquid provided to the nozzle  22 . Controlling the gas provided to the pump  26  or the nozzle  22  controls the gas-to-liquid mass flow ratio and, thereby controls the discharge from the nozzle. 
     For example, less gas provided to the pump  26  can decrease the rate that the pump  26  delivers liquid to the conduit  24 . To increase the gas-to-liquid ratio in one example, the controller  40  causes the regulator  42  to decrease the amount of gas or the pressure of the gas provided to the pump  26 . In another example, the controller  40  causes the regulator  44  to increase the amount of gas or the pressure of the gas provided to the nozzle  22  (or the conduit  24 ). Another example includes controlling both regulators  42  and  44  to increase the gas-to-liquid ratio by increasing the gas provided through the regulator  44  and decreasing the gas provided through the regulator  42 . 
     The controller  40  can also decrease the gas-to-liquid ratio by increasing the amount of gas that flows through the regulator  42  or the pressure of the gas through the regulator  42  for driving the pump  26 . Increasing the output of the pump  26  by increasing the pressure or amount of gas used to drive the pump without changing the gas flow provided to the conduit  24  or nozzle  22  will decrease the gas-to-liquid ratio used for achieving a desired discharge from the nozzle  22 . In another example, the controller  40  decreases the amount of gas provided to the conduit  24  or the nozzle  22 . One example includes decreasing the gas provided to the nozzle  22  while increasing the gas provided to drive the pump  26  to achieve a desired, decreased gas-to-liquid ratio. 
     Whether the amount or pressure through either regulator changes may depend on the configuration of the regulator. For example, the regulator may comprise an expansion valve. By increasing the opening size of the expansion valve, a different resulting pressure of gas provided for driving the pump  26  will be realized. Another example regulator comprises a valve having a variable flow-through opening. By increasing the opening of the valve, an increased amount of gas provided to the pump  26  may be realized. Given this description, those skilled in the art will be able to select appropriate pump and regulator components and to control the gas provided to the particular pump they select in a manner that meets the needs of their particular situation. 
     Selectively varying the gas provided to the pump  26  or the nozzle  22  allows for selectively varying the gas-to-liquid ratio and, consequently, to vary the discharge from the nozzle  22 . Varying the air-to-liquid ratio achieves different performance characteristics of the system  20 . For example, different droplet size of a misting nozzle  22  may be achieved depending on the gas-to-liquid ratio. The velocity of discharge from the nozzle  22  also can be selectively controlled. The discharge pressure or discharge distance may also vary depending on the air-to-liquid ratio. 
     The illustrated example includes the controller  40  selectively varying the amount of gas used for driving the pump  26  or provided to the nozzle  22  for achieving at least two different performance characteristics each associated with the discharge from the nozzle  22 . Taking droplet size as an example performance characteristic, the controller  40  controls the gas provided for driving the pump  26  or provided to the nozzle  22  to achieve two different droplet sizes discharged from the nozzle  22 . Each performance characteristic or droplet size provides a different effect for fire suppression. 
     By selectively varying the gas-to-liquid ratio to achieve different discharge effects from the nozzle  22 , the illustrated example allows for addressing different types of fire situations from a single system, for example. Some fire conditions may require a higher concentration of fire suppressing fluid directly beneath a nozzle while others may require a more widely dispersed discharge of the fire suppressing fluid. Utilizing different discharge pressures, velocities, droplet sizes or a combination of these during a single activation of the system  20  allows for addressing these different types of fire conditions using the single system. This feature enhances the overall capabilities of the system  20  compared to a system that only provides one type of nozzle discharge during system activation. The controller  40  in the illustrated example selectively varies the gas provided to the pump  26  or the gas provided to the nozzle  22  to achieve more than one performance characteristic during a single activation of the system  20 . Not only does the varying performance characteristic allow for addressing different types of fire situations but it may enhance the ability to more quickly address a particular type of fire condition. 
     In one example, the controller  40  continuously varies the gas-to-liquid ratio by varying at least one of the gas provided for driving the pump  26  or the gas provided to the nozzle  22  between selected maximum and minimum values. In one example a sinusoidal pattern for varying the gas allows for a smooth, continuous transition over time. This allows for a relatively continuous variation in the discharge from the nozzle  22  and a cycling back-and-forth between selected extremes (e.g., maximum and minimum droplet size). 
     Another example includes the controller  40  varying the gas provided to the pump  26  or to the nozzle  22  intermittently between selected values. In one such example, the controller  40  effectively follows a square wave pattern between a high and low value of the varied amount of gas. This allows for pulsing the discharge from the system, for example. 
     In one example, the variation has a frequency between 0.01 Hz and 1.0 Hz such that the discharge from the nozzle  22  varies between two selected extremes at an interval in a range between every second and every ten seconds. 
     One example includes the controller  40  monitoring an amount of fluid provided to the pump  26  from the source  28 . In some cases, the amount of fluid available may vary over time. To achieve a consistent or desired discharge from the nozzle  22 , the controller  40  adjusts the gas provided for driving the pump  26 , to the nozzle  22  or both to ensure that the desired discharge from the nozzle  22  is achieved even when there may be a variation in the amount of fluid available for the pump  26  to provide to the nozzle  22 . In one such example, the discharge from the nozzle  22  does not change over time even though the gas-to-liquid ratio is changed by the controller  40 . 
       FIG. 2  illustrates another example embodiment of a fire suppression system  20 . In this example, the amount of gas provided along the branch  36  to the conduit  24  or the nozzle  22  does not vary. This example includes a high level regulator  50  and a low level regulator  52  between the gas supply line  32  and the pump  26 . A valve  54  controlled by the controller  40  switches between the regulators  50  and  52  depending on whether more or less gas for driving the pump  26  is desired. The illustrated example includes a solenoid valve  54  for this purpose. This example allows for varying the water pressure or the amount of water supplied by the pump  26  to the nozzle  22  (when water is the selected fire suppressing fluid). Varying the amount of gas for driving the pump  26  allows for achieving different gas-to-liquid ratios at the nozzle  22  and, consequently, achieving different discharge from the nozzle  22 . 
     One feature of the illustrated examples is that relatively simple component design can be incorporated into the system  20 , which minimizes complexity and cost. For example, the nozzle  22  need not have any switching components for purposes of varying the flow from or discharge from the nozzle  22 . Instead, the controller  40  selectively controls the gas-to-liquid ratio for purposes of selectively varying the discharge from the nozzle  22 . Eliminating moving parts within the nozzle  22  simplifies the design and provides a more reliable system, for example. 
     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.