Abstract:
A telescopic high pressure sprinkler system is provided with a plurality of gaskets forming sliding seals between the piston and the outer conduit. Thus, the volume between the piston and the outer conduit forms a fluid chamber that is compressed as the piston is deployed so as to dampen the acceleration of sprinkler deployment. Furthermore, adjustable bleeder holes are provided to regulate the fluid chamber&#39;s compression while the gaskets provide a cushion when the piston comes to a stop. These bleeder holes also allow refilling of the piston fluid chamber.

Description:
This application is a Continuation-in-Part of the patent application entitled DEVICE FOR REGULATING SPEED OF DEPLOYMENT OF SPRINKLER HEADS IN PREACTIVE SPRINKLER SYSTEMS (Ser. No. 08/782,069) filed on Jan. 13, 1997 and now issued as U.S. Pat. No. 5,921,322. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to sprinkler systems and more specifically this invention relates to preaction telescopic automatic fire sprinkler systems in residential, commercial, and industrial buildings where the telescopic sprinkler assemblies are deployed repeatedly. 
     2. Background of the Invention 
     Automatic fire extinguisher sprinkler systems have become an integral part of modern residential, commercial, and industrial buildings. Automatic sprinkler systems also are used in agriculture and in several manufacturing processes. Commonly these systems include a network of pipes for distributing fluid (hereinafter designated as the “spray fluid”) to a plurality of sprinkler heads. Often, the spray fluid is injected at high pressure in the pipe network only after a command therefor has been generated, either automatically, for instance by a heat sensor for a fire-extinguishing system, or manually by an operator. 
     There are several applications where the sprinkler heads are not permanently installed in their spraying position but rather are installed in what are commonly referred to as “telescopic sprinkler systems.” Some applications include anechoic enclosures, environmental chambers and freezers. 
     In a telescopic sprinkler system, a sprinkler head is installed at a depending end of a conduit, or “piston”. The first end of the piston is adapted to be slidably received by an “outer conduit” or cylinder. The outer conduit in turn is rigidly attached to the pipe network. When there is no high pressure in the fluid network, the piston is fully nested within the outer conduit. To deploy the sprinkler heads to their spraying positions, a high pressure fluid (for example either the spray fluid or compressed air) is injected into the network and the pistons are propelled outward at high speed until they strike a stop and suddenly come to rest. 
     Telescopic sprinkler systems also are utilized in a myriad of applications in addition to fire extinguishing. For instance, where a sprinkler system is used to provide water for agriculture or horticulture, the sprinkler heads are often installed underground so that they will not interfere with pedestrians, vehicles, or machinery above ground. Also, for esthetic reasons, some land owners prefer that the sprinkler heads not be visible when they are not in use. The same considerations apply to overhead sprinkler systems used for fire extinguishing. Often building users prefer that the sprinkler heads be recessed in the ceiling for esthetic reasons or because they would interfere with other equipment contained in the room. Moreover, designers of anechoic acoustical enclosures require that sprinkler heads be recessed in the ceiling so that they not generate unwanted reflections. Similarly, designers of enclosures shielded from radio frequency radiation require that the sprinkler heads be recessed so that they do not impart unwanted reflections. 
     High pressure telescopic sprinkler systems must be able to withstand repeated deployment. For instance, fire extinguisher systems are tested at regular intervals so as to ensure both that the piston pipes will deploy appropriately and that sprinkler heads are suitably positioned in case of a fire. This is accomplished by introducing high pressure air or water in the distribution system. This high pressure accelerates the piston downwardly and out of the outer conduit until it strikes a stop at very high velocity. High velocity piston/stop impacts cause the telescopic system to suffer considerable damage after only a small number of tests. Such slamming causes water to leak into the room. In extreme cases, either the stop, or a surface on the piston that is complementary to the stop, shears off causing the piston to shoot towards the floor of the facility. This leads to flooding and further damage in instances where the piston strikes an object. However, most damage is internal or otherwise undetected unless the telescopic system is taken apart after a test. Thus, tests of a telescopic sprinkling system provide inadequate assurance that the system will deploy properly in case of an actual fire. 
     Damage incurred by the telescopic system cannot be obviated by reducing the pressure of the fluid injected in the distribution network. Adequate operation of the sprayer heads require that the spray fluid be applied at high pressure. For such applications as fire extinguishing, a high volume of spray fluid must be sprayed as quickly as possible, requiring that the spray fluid be at high pressure. Finally, when the telescopic systems are not deployed frequently, there is considerable static friction impeding the deployment of the systems, and again high pressure is required to overcome this friction. 
     Examples of telescopic high pressure sprinkler systems are described in several United States patents. U.S. Pat. No. 3,194,316, issued Jul. 13, 1965, U.S. Pat. No. 3,847,392, issued Nov. 12, 1974, U.S. Pat. No. 3,675, 952, issued Jul. 11, 1972, U.S. Pat. No. 4,091,872, issued Mar. 30, 1978, and U.S. Pat. No. 5,160,174, issued Nov. 3, 1992, teach methods for adjusting the length of a telescopic sprinkler system when it is first installed but make no provision for regulating the speed of deployment of such systems. U.S. Pat. No. 3,263,929, issued Aug. 2, 1966, is an overhead sprinkler system for watering lawns. It incorporates an air chamber complete with an evacuation port. The air chamber is used to selectively actuate a specific sprinkler, but again no provision is made for regulating the speed of deployment of the telescopic sprinkler. 
     A need exists in the art to provide telescopic sprinkler systems for fire extinguishing and other applications wherein the velocity of the piston/stop impact is regulated so as to prevent damage to the telescopic assembly during testing or in actual fire-suppression scenarios. The improved telescopic sprinkler assembly should be easily adjustable (i.e., without the substitution of major portions of the assembly) so as to provide various sprinkler-head deployment speeds at the same extinguishing fluid pressures, or alternatively, constant sprinkler-head deployment speeds at various extinguishing-fluid pressures. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a device for the controlled deployment of telescopic sprinkler heads that overcomes many of the disadvantages of the prior art. 
     A principal object of the present invention is to provide a telescopic high pressure sprinkler system wherein the velocity of deployment of the sprinkler heads, each of which is attached to a piston nested in a cylinder, is regulated. A feature of the present invention is a plurality of gaskets or seals in sliding contact with the inner wall of the cylinder. An advantage of the present invention is that an air pocket, defined by positions of opposing gaskets serves to dampen deployment speeds of the sprinkler head as the pocket is longitudinally shortened. 
     A further object of the present invention is to provide a telescopic high pressure sprinkler system wherein the velocity of deployment of sprinkler head pistons which are initially nested in conduit cylinders, is substantially reduced at the end of deployment. A feature of the present invention is that a plurality of gaskets, in sliding contact with the inner wall of the piston cylinder, form a fluid chamber between the cylinder and the piston. An advantage of the present invention is that the fluid chamber is progressively compressed as the system is deployed and thus exerts a progressively higher counter pressure on the sprinkler piston. 
     Another object of the present invention is to provide a telescopic high pressure sprinkler system wherein a high pressure is exerted on a sprinkler-head piston which is nested inside a cylinder, at the start of the system&#39;s deployment. A feature of the present invention is that the fluid chamber between the piston cylinder and the piston exerts a low counter pressure at the start deployment. An advantage of the present invention is that at the start of deployment, the net force exerted on the piston is nearly equal to the maximum force which the high pressure of the sprinkler system can exert. 
     A further object of the present invention is to provide a telescopic high pressure sprinkler system wherein the velocity of deployment of the sprinkler heads is adjustable. A feature of the present invention is one or a plurality of venting means, such as bleeder holes with adjustable apertures to allow for the progressive evacuation of fluid such as air from a chamber defined by the outer surface of a piston containing the sprinkler head and an inner surface of a piston cylinder. An advantage of the present invention is that the bleeder holes allow the adjustment of the counter pressure exerted by said fluid chamber. Another advantage is that the adjustable apertures allow for varying or maintaining the sprinkler-head deployment speed at the same or different pressures of extinguishing fluid. 
     Yet another object of the present invention is to provide a telescopic high pressure sprinkler system wherein the impact between a piston carrying a sprinkler head and a piston cylinder is lessened. A feature of the present invention is one or a plurality of cushioning means, such as flexible gaskets or springs positioned between the rigid stops mounted on the piston and the cylinder. An advantage of the present invention is that the gaskets or springs cushion the impact between the piston and the outer conduit. 
     Still another object of the present invention is to allow already installed telescopic high pressure sprinkler systems to be modified so that the velocity of deployment of the sprinkler heads becomes adjustable. A feature of the present invention is that it requires a limited number of modifications on already installed sprinkler systems. An advantage of the present invention is that such sprinkler systems can be modified at low cost. 
     In brief, the objects and advantages of the present invention are achieved by providing a device for deploying sprinkler heads in a telescopic sprinkler system comprising a plurality of gaskets and a chamber containing fluid for dampening the speed of deployment of the sprinkler heads. 
     In addition, a device for deploying sprinkler heads in a preaction sprinkler system is provided comprising a conduit; a piston slidably received by said conduit, whereby the piston has a first end and a second end; a first seal positioned on the first end of the piston; a sprinkler head positioned on the second end of the piston; a second seal positioned on the conduit and circumferentially contacting a surface of the piston proximal to the sprinkler head so as to define a fluid space containing fluid between the first and the second seal when the piston is substantially contained by the conduit; and a stop attached to the first end of the piston and proximal to the first seal so that when a fluid contacts the stop with a sufficient force, the piston will travel toward the second seal a predetermined distance. 
     Furthermore, a device for deploying telescopic sprinkler systems is provided comprising a device for deploying sprinkler heads in a preactive sprinkler system comprising a first conduit having first and second ends; a second conduit longitudinally received within said first conduit; said second conduit having a first end with sealing means attached thereto for sealing an outer wall portion of said first end of said second conduit adjacent to a longitudinally varying inner wall portion of said first conduit; said second conduit having a second end with a means for distributing a fluid; means for sealing an inner wall portion of said second end of said first conduit adjacent to a longitudinally varying outer wall portion of said second conduit; and means for stopping said first end of said second conduit when a predetermined longitudinal movement of said second conduit has occurred. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention together with the above and other objects and advantages may best be understood from the following detailed description of the embodiment of the invention illustrated in the drawings, wherein: 
     FIG. 1 is a cross-sectional view of an exemplary embodiment of the device in a “nested” configuration, in accordance with features of the present invention; 
     FIG. 2 is a cross sectional view of an exemplary device, depicting initial deployment, in accordance with feature of the present invention; 
     FIG. 3 is a cross sectional view of an exemplary device depicting final deployment, in accordance with features of the present invention; 
     FIG. 4 is a partial detailed view of an exemplary device, in accordance with the features of the present invention; 
     FIG. 5 is a partial detailed view of an exemplary device with an alternative fluid evacuation configuration, in accordance with features of the present invention; 
     FIG. 6 is an elevated cutaway view of an exemplary device for varying the diameter of an aperture, in accordance with features of the invention; 
     FIG. 7 is an elevated view of another device for varying the diameter of an aperture, in accordance with features of the present invention; and 
     FIG. 8 is a view of FIG. 7 taken along lines  8 — 8 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to high pressure automatic telescopic sprinkler systems wherein a first tubular member or pipe (“the piston”) is slidably received by a second tubular member or pipe (“the outer conduit”), and wherein the piston is deployed at a predetermined speed until it rests against a stop. The present invention employs a plurality of gaskets to create a fluid chamber within the telescopic sprinkler assembly. The fluid chamber acts as a brake by exerting a counter pressure against the piston, thereby regulating the velocity with which the piston strikes the stop. Optimally, the piston and/or the cylinder contains regions defining a means for venting fluid such as an aperture or a plurality of apertures hereinafter referred to as bleeder holes, which allow for the progressive evacuation of the fluid chamber so that the counter pressure can be adjusted. The fluid-venting means may be made adjustable, details for which are provided infra. 
     FIG. 1 depicts a cross sectional view of an exemplary embodiment of the present invention in a “nested” configuration. The invented device, designated generally as numeral  10 , contains a first, generally cylindrical conduit  11  (hereinafter designated as the “outer conduit”) with a first end  15  and a second end  19 . The first end  15  is connected to the sprinkler system distribution network by means of a conventional Tee junction. (Not shown) A second generally cylindrical conduit  21  (hereinafter designated as the “piston”) having a first end  25  and a second end  29 , is adapted to be slidably received by the outer conduit  11  in a piston-cylinder fashion. 
     As is more clearly depicted in FIG. 4, which is a partial cutaway of the device  10  without the sprinkler head  28  detail, and with a slightly modified sealing means, a cylindrical mounting  16  is rigidly attached to the second end  19  of the outer conduit  11 . The cylindrical mounting  16  can be rigidly attached by a myriad of attachment means including welds or a threaded junction. The cylindrical mounting  16  comprises a stop  14  and a plurality of annular grooves  20  for the positioning of a plurality of gaskets  18 , such as O-rings. The stop  14  is immobile relative to the piston  21 . The gaskets  18  provide a primary, slidable seal between the mounting  16  and the outer wall  22  of the piston  21 . Optionally, one may also position an annular gasket  17  so as to contact a surface  26  of the stop  14 . 
     A commonly used sprinkler head  28  is attached via a male-female threaded configuration to the second end  29  of the piston  21 . A second stop  37  having a surface  23  complementary to a surface  26  of the first stop  14  is rigidly attached to the first end  25  of the piston  21  by means of a welded or machine-threaded junction. In FIGS. 1-3, the stop  37  is integrally molded as a machined part  36  having a plurality of annular grooves  20  adapted to receive “O” rings  18  to serve as a secondary seal. 
     In FIG. 4, an alternative secondary seal is depicted whereby a compliant annular sleeve such as a gasket  41  is positioned on the piston distal and juxtaposed to the stop  37 . The sleeve  41  contacts the inner wall  43  of the outer conduit  11  so as to provide a slidable seal between the stop  37  and the inner wall  43 . A groove  44  distal to the gasket  41  provides a means for receiving a snap ring  45  to maintain the gasket  41  in place. Alternatively, an annular plate, coaxial to the piston  21 , could be tack-welded onto the piston just distal to the gasket  41  to maintain the position of the gasket. In this latter case, care must be taken not to thermally compromise the gasket  41 . Alternatively, the gasket  41  could be stretched over the tack-weld. 
     The use of O-rings in the secondary seal configuration, as depicted in FIGS. 1-3, obviates the need for the gasket retaining means  45 . 
     Yet a third configuration for providing the secondary seal is through a piston/piston-ring arrangement. In this third configuration, the inner conduit or piston  21  is formed into a honed cylinder adapted to receive one or a plurality of annular rings, such as piston rings, whereby the annular rings are juxtaposed relative to the outer conduit  11  in a manner similar to the O-rings  18  received by the machined part  36  of the secondary seal depicted in FIGS. 1-3. Such a piston-ring arrangement would obviate the expense associated with providing the machined part  36 . The volume between the gasket assembly  18  positioned at the second end  19  of the outer conduit  11  and the secondary seal positioned at the first end  25  of the piston  21  forms an annular chamber or cavity  49 . This cavity may be filled by air or by any other suitable fluid hereinafter designated as “piston fluid.” Suitable pressurized fluids include, but are not limited to, air, water, halon, helium, nitrogen. 
     Operation Detail 
     Generally, when the device is used in a fire extinguishing system, it is actuated in one of two scenarios. The first scenario is when a fire- or heat- sensing system detects heat or fire, and a high pressure fluid fills the sprinkler system distribution network. The second scenario is when deployment of a telescopic sprinkler system is tested by injecting a high pressure fluid (most often compressed air) in the distribution network. Typical pressures to which sprinkler systems are subjected can approach, and in some cases exceed, 150 pounds per square inch (psi). For example, pressures of approximately 200 psi may be applied to some telescoping systems. 
     When a high pressure fluid is introduced in the head space or volume  53  above the piston stop  37 , the fluid impacts a fluid-impacting surface  60  of the piston-attached stop  37  thereby causing the piston to travel downwardly towards the second end  19  of the outer conduit. FIG. 2 provides a cross-sectional view of the device at an initial stage of telescopic deployment. FIG. 3 provides a cross-sectional view of the device at its full deployment stage. The piston fluid contained in the cavity  49  is thereby compressed and thus exerts a counter force which dampens the velocity of the piston. 
     To expedite evacuation of the piston fluid, portions of the piston  21  may form one or a plurality of venting means such as radially-situated channels or apertures  57  to allow for fluid communication between the confined space  49  and the interior  30  of the piston  21 . Generally these apertures  57  or bleed holes are positioned distal to the secondary seal region along the piston so as to allow for the escape of the piston fluid from the cavity  49  into the volume  53 . The diameter and number of the bleed holes can be selected so that the piston  21  is allowed to travel towards the second end  19  of the outer conduit at an appropriate speed. That speed is determined by the impact that can be sustained by the piston stop  37  and the conduit stop  14 . One may fashion these bleeder holes so as to maximize the rate of escape of the piston fluid from the piston chamber relative to the rate of entry of the spray fluid into the piston chamber. For instance one may orient the bleeder holes so that the piston fluid will flow downwardly while entering spray fluid will flow upwardly. Moreover, one may make the bleeder holes variable in diameter, as discussed infra. 
     Optional gaskets  17  provide a spring-like cushion as the piston-attached stop  37  impacts upon the conduit stop  14 . As an alternative or supplement to the gasket  17  resting on top of complementary surface  26 , a spring could be employed as a cushioning means, whereby the spring is configured to slidably receive the piston  21 , the spring is also configured so that a first end of the spring rests upon the complementary surface  26 , and a second end ultimately contacts complementary surface  23  when the piston is substantially deployed. When the first and second ends of the spring are simultaneously contacting the complementary surfaces  26  and  23  respectively, the resistive force of the spring due to further longitudinal compression of the spring, will serve to cushion deployment impact of the piston-attached stop  37  against the cylinder-attached stop  14 . 
     Optionally, especially when the piston fluid is air, one may situate pressure relief apertures  57  or valves  61  proximal to the gasket  18  in the second end  19  of the outer conduit  11 . This configuration is depicted in FIG.  5 . As discussed more fully supra, these relief valves may be made adjustable to withstand supervisory pressures to which the undeployed system is constantly exposed. This latter option has the further advantage that the relief valves can be activated when “re-nesting” or resetting the pistons after deployment. This option provides a means to evacuate the confined cavity  49  of any fluid such as water contained therein due to leakage or imperfect seal formation. 
     A myriad of rigid materials are suitable for the two conduits. Relevant to the choice of materials include cost, ability to withstand the high pressures and high velocity impacts associated with the sprinkler system operation, static and kinetic friction between the gaskets and the walls of the conduits, long term durability, and resistance to corrosion. 
     Also, a wide variety of elastic materials are suitable for gaskets  17 ,  18 , and  41 . The choice of materials for the gaskets depends on the smoothness of the walls of the piston and of the outer conduit and the nature of the high pressure and piston fluids. Generally, materials with inherent lubricity are suitable gasket materials, such as various fluorocarbon resins (e.g. polymers of tetrafluoroethylene or hexafluoropropylene). Otherwise, any gasket material that is compatible with silicone grease is suitable, whereby the grease is applied to the gaskets prior to final assembly of the device. In an exemplary embodiment of the present invention, rubber was utilized for gasket  17 , neoprene O-rings for gaskets  18 , and standard rubber tubing for the gasket  41 . Tubing without internal threads or other absorbent, rubber-substrate support means is preferable to minimize wicking of grease. 
     Lubricity between the gaskets and the opposing inner walls of the device can be further facilitated by coating the surfaces to prevent corrosion. Alternatively, a noncorrosive material, such as stainless steel or galvanized material can be utilized. 
     Lastly, gaskets connected to the secondary seal configuration may not be required if a suitable close tolerance between the piston-attached stop  37  and the inner wall  43  of the outside conduit  11  is obtainable so as to provide slow deployment (i.e., deployment without concomitant damage to the microstructure of the device)of the sprinkler head. 
     Fluid Evacuation and Refilling Means Detail 
     As noted supra, the various fluid evacuation means utilized in this invention include apertures, valves or a combination thereof incorporated into either the piston walls, cylinder walls, or both. 
     While the apertures can regulate fluid by being bored to a specific diameter, the apertures also can be adjustable to effect a variety of diameters. 
     A myriad of techniques exist for varying the diameters of the apertures  57 . One exemplary means for varying diameters is depicted in FIG. 6. A threaded bore  65  is adapted to receive a complementarily threaded bushing  68  defining an axially extending through bore. The bushing  68  is chosen based on the inner diameter  70  of its bore. Any commercially-available bushing or reducer coupling having the desired inner diameter is suitable. 
     Through experimentation, inner diameters are chosen based on their effect on deployment speeds of the sprinkler head at various extinguishing fluid pressures. Generally however, the smaller the inner diameter, the more restrictive the fluid flow through the apertures  57 . Conversely, a larger diameter provides less restrictive fluid flow through the diameter. Such less restrictive fluid-flow out of the annular space  49  results in less of a compressive counter-force directed against the approaching opposing surface  23  of the piston attached stop  37  of the deploying piston. 
     As an alternative to the use of typical bushings or reducer couplings, cored-out plugs which are adapted to be flush-mounted to the aperture  57  are available. Such an adjustable plug is depicted in FIGS. 7 and 8. Essentially, a threaded plug  72  defining a longitudinally extending aperture  74  is mated with the threaded aperture  65 . The plug  72  has a first externally accessible end  73  and second end  75 , both ends through which the aperture or channel extends. Further, the plugs  72  have circumferentially-arranged threads  76  which are matingly received by the threaded aperture  65 . 
     The externally-accessible end  73  of the plug defines a surface  78  which is adapted to interact with a hex tool, slotted tool, or other device to effect rotational movement of the plug inside the aperture. Generally, the surface  78  extends inwardly along the longitudinal axis of the plug and terminates at an outwardly facing end  80  of the channel  74 . The above-described plugs are widely available commercially. 
     The placement of adjustable fluid evacuation means on the cylinder wall of the device (as depicted in FIG. 5) may not necessitate flush mounting of the adjustable device. Indeed, there are instances where manual actuation (i.e., without the need for hand tools) of the orifice is desired. In such instances, a valve or spigot received by the threaded aperture is suitable. This valve or spigot option also allows for the provision of a manifold (not shown) removably connected to the valves or spigots in order to refill the piston cavity with piston fluid after the piston has been deployed. In the alternative one may removably connect a piston fluid supply to the apertures  57  in a male-female configuration by utilizing the threaded bores  65 . In both alternatives one may regulate the speed of refilling of the piston cavity and refill the piston fluid at a high enough pressure to re-nest the sprinkler after deployment. 
     EXAMPLE 
     An exemplary embodiment of the device has been constructed from ordinary materials to illustrate the utility of the invention in radio frequency-shielded environments. In this example, 1 ½″ schedule  40  black pipe was utilized as the outer conduit  11  or piston cylinder. The first end  15  of the outer conduit  11  is ideally suited to extend through magnetic field or RF-shielded channels  62  to attach to a water supply network. As depicted in FIGS. 1-3, the channels  62  may be outfitted with a cap plate  63 , whereby the cap plate  63  forms an aperture to receive the outer conduit  11 . The cap plate may be attached to the outer conduit  11  via welds  64 . 
     The second end  19  or depending end of the outer conduit  11  slidably received an inner conduit or piston  21 , which was fabricated from 1 inch stainless steel pipe, schedule  80 .As depicted in FIGS. 1-3, the first end  25  of the piston  21  was adapted to receive a 1″ NPS×¾″ machined part  36 , to serve as the integrally molded piston-attached stop  37  and O-ring holder  20 . 
     As noted supra, an alternative piston-attached stop  37  can be configured from 1″ NPT×¾″. Juxtaposed distally to the piston-attached stop  37  is the annular sleeve or gasket  41 . While any compressible material is suitable to comprise the gasket  41 , sections of common rubber hose, cut to lengths of approximately ½ inches were utilized. 
     Once the piston  21  was fully nested concentrically within the cylinder  11 , a 1½″×1″ reducer coupling was threaded onto the second end  19  (depending end) of the outer cylinder  11 . An inner surface of the reducer coupling defines the stop  14  having a surface  26  complementary to an opposing surface  23  of the piston-attached stop  37 . The inner surface of the reducer coupling also defined a region to receive one or more O-rings comprised of nitrile rubber. 
     Initially in the resting or “nested” position, as depicted in FIGS. 1 &amp; 2, the stainless steel pipe/piston  21  is actuated downwardly when a fluid (e.g. water, halon, etc.)of sufficient force impacts the fluid-impacting surface  60  of the piston-attached stop  37 . Pressures applied for deployment ranged from approximately 15 pounds per square inch to 40 pounds per square inch. 
     Generally, deployment pressures can supersede supervisory pressures which often are used to monitor the integrity of the system, such supervisory pressures generally ranging from approximately less than 1 psi to 30 psi. To maintain the piston  21  in its nested configuration while supervisory pressures are applied, and to re-set deployed pistons into the nested configurations, one or more means for retaining the piston may be employed, including, but not limited to ball plunger configurations whereby a spring-biased pin  12  mates with an annular groove  27  formed on the outer surface  22  of the piston  21 , as depicted in FIG.  4 . Such piston-retaining means are adjustable to the supervisory air pressure used. An exemplary adjusting means includes a set screw  13  to vary tension of a spring  9  which is applying outward pressure to the pin  12 . Exemplary ball-spring plungers for use as the piston-retaining means are available from VLIER INC., Brighton, Mass. 
     Upon full deployment, see FIG. 3, the system remains charged. Water or other fluid flows through the sprinkler head  22  only when heat links  24  or manual systems are actuated. Typical telescoping sprinkler systems are reset or “re-nested” manually. However, a negative pressure applied remotely from the depending sprinkler pistons also could cause re-nesting to occur. Such negative pressure could be applied to the water network system in a procedure opposite to the application of the deployment pressure. 
     While the invention has been described with reference to details of the illustrated embodiment, these details are not intended to limit the scope of the invention in the appended claims. For example, while the above description depicts a separate substrate  62  as a radio frequency protection element, the outer conduit  11  of the device could also serve this purpose, thereby precluding the need for element  62  or such additional RF attenuation substrates. 
     The embodiment of the invention in which an exclusive property or privilege is claimed is defined as follows: