the present invention relates to high pressure automatic telescopic sprinkler systems wherein a first tubular member or pipe (&# 34 ; the piston &# 34 ;) is slidably received by a second tubular member or pipe (&# 34 ; the outer conduit &# 34 ;), and wherein the piston is deployed at 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 counterpressure against the piston , thereby regulating the velocity with which the piston strikes the stop . optimally , the piston 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 counterpressure can be adjusted . fig1 depicts a cross sectional view of an exemplary embodiment of the present invention in a &# 34 ; nested &# 34 ; configuration . the invented device , designated generally as numeral 10 , contains a first , generally cylindrical conduit 11 ( hereinafter designated as the &# 34 ; outer conduit &# 34 ;) 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 &# 34 ; piston &# 34 ;), 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 fig4 which is a partial cutaway of the device 10 without 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 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 the 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 fig1 - 3 , the stop 37 is integrally molded as a machined part 36 having a plurality of annular grooves 20 adapted to receive &# 34 ; o &# 34 ;- rings 18 to serve as a secondary seal . in fig4 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 fig1 - 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 fig1 - 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 &# 34 ; piston fluid &# 34 ;. 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 . other suitable pressurized fluids include water , halon , and helium . 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 . fig2 provides a cross - sectional view of the device at an initial stage of telescopic deployment . fig3 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 counterforce 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 adjusted 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 adjustable in diameter . 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 provide pressure relief valves ( not shown ) proximal to the gasket 18 in the second end 19 of the outer conduit 11 . 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 &# 34 ; re - nesting &# 34 ; 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 hexafluoroproylene ). 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 , copper - based alloy , or internally plated metallic surfaces 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 . an exemplary embodiment of the device was constructed from ordinary materials to illustrate the utility of the invention in radio frequency - shielded environments . specifically , 11 / 2 &# 34 ; schedule 40 black pipe was utilized as the outer conduit 11 . 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 fig1 - 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 fig1 - 3 , the first end 25 of the piston 21 was adapted to receive a 1 &# 34 ; nps × 3 / 4 &# 34 ; 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 &# 34 ; npt × 3 / 4 &# 34 ; coupling . 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 1 / 2 inches were utilized . once the piston 21 was fully nested concentrically within the cylinder 11 , a 11 / 2 &# 34 ;× 1 &# 34 ; 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 26 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 &# 34 ; nested &# 34 ; position , as depicted in fig1 & 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 fig4 . 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 fig3 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 &# 34 ; re - nested &# 34 ; 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 :