US3812914A

US3812914A - Automatic on-off sprinkler

Info

Publication number: US3812914A
Application number: US00385130A
Authority: US
Inventors: J Mears
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1973-08-02
Filing date: 1973-08-02
Publication date: 1974-05-28
Anticipated expiration: 1991-05-28
Also published as: NO141782C; BE818414A; GB1472569A; DE2434721A1; FR2239261A1; IT1017708B; FR2239261B1; SE389273B; LU70641A1; DK407874A; AU7127874A; JPS5043796A; NL7410034A; NO141782B; SE7409841L; NO742599L

Abstract

An automatic water sprinkler has a cylindrical control chamber formed in a body portion and a line pressure operated piston valve slideably and sealingly disposed therein for closing a downstream end of a fluid inlet member. A centrally positioned tubular guide member is mounted to the piston and inserted into a bore formed in said body portion for guiding the piston in the control chamber during reciprocation. A passage is centrally formed in said piston for communicating the inlet member with the control chamber through the tubular guide and bore so that the control chamber is exposed to the inlet fluid pressure. The effective area of the piston exposed to the control chamber fluid pressure is greater than that exposed to the inlet member fluid pressure to thereby establish a differential force for closing the piston valve. A ball is disposed in the bore and adapted to rest on an end of the tubular member for closing the tubular guide member and forming a unidirectional check valve to prevent sprinkler operation as a result of fluctuating inlet fluid pressure.

Description

United States Patent i 1 Mears [111 3,812,914 [45.] May 28, 1974 AUTOMATIC ON-OFF SPRINKLER Inventor: James William Mears Warwick, RI. 7

Assignee: International Telephone and Telegraph Corporation, Nutley, NJ.

Filed: Aug. 2, 1973 Appl. No.: 385,130

U.S. Cl. 169/20, 169/37 Int. Cl A62c 37/06, A620 37/10 Field of Search 169/ 19-22, 169/37 [56] References Cited UNITED STATES PATENTS 9/1916 10/1972 Martin et al. 11/1972 Grenier 169/20 FOREIGN PATENTS OR APPLICATIONS Primary ExaminerRobert S. Ward, Jr. Attorney, Agent, or Firm-.lohn T. OHalloram-Menotti J. Lombardi, Jr.; Peter Van Der Sluys Meloon 169/20 Great Britain 169/19 I [57] ABSTRACT An automatic water sprinkler has a cylindrical control chamber formed in a body portion and a line pressure operated piston valve slideably and sealingly disposed therein for closing a downstream end of a fluid inlet member. A centrally positioned tubular guide member is mounted to the piston and inserted into a bore formed in said body portion for guiding the piston in the control chamber during reciprocation. A passage is centrally formed in said piston for communicating the inlet member with the control chamber through the tubular guide and bore so that the control chamber is exposed to the inlet fluid pressure. The effective area of the piston exposed to the control chamber fluid pressure is greater than that exposed to the inlet member fluid pressure to thereby establish a differential force for closing the piston valve. A ball is disposed in the bore and adapted to rest on an end of the tubular member for closing the tubular guide member and forming a'unidirectional check valve to prevent sprinkler operation as a result of fluctuating inlet fluid pressure.

7 Claims, 2 Drawing Figures 1 AUTOMATIC ON-OFF SPRINKLER BACKGROUND OF THE INVENTION 1. Field of the lnvention This invention relates to sprinkler systems and more particularly to an automatic ON-OF F sprinkler.

2. Description of the Prior Art Conventional sprinkler heads for tire sprinkler systems were single operation devices. A heat responsive member usually formed of a fuseable material held a plug in position to prevent the flow of water from the sprinkler head. When the heat responsive member was subjected to temperatures above a predetermined level, the fuseable material melted allowing the plug to open so that fire extinguishing fluid escaped. Once the sprinkler head was operated, the valve remained open and water continued to be released even after the fire was extinguished. In most cases the water supply to the sprinkler system had to be manually shut off at centrally located water supply line. The result in many cases was that greater loses were inflicted by the water than by the fire itself, especially at times when the sprinkler operation was not discovered for a relative long period after the fire had been extinguished.

Recent developments in the field of sprinkler systems have provided sprinklers with automatic cut off provisions so that the water flow is interrupted when the fire is extinguished and the ambient temperature subsides to a normal level. Examples of such devices may be found in U.S. Pat. Nos. 3,698,483 and 3,702,160. Another device is taught in copending patent application Ser. No. 196,641, filed Nov. 8, 1971 and commonly assigned with this application.

The automatic devices all use line pressure operated differential area piston valves to control the flow of fluid from the sprinklers. The line pressure operated differential area piston valves of these devices are slideably mounted within control chambers and fluid passages are provided within the piston valves for communicating line pressure to the control chambers so that the differential area piston valves are forced into a position to shut off fluid flow.

Temperature responsive pilot valves were provided to open or close the control chambers in response to the ambient temperature whereby the control chambers could be vented and the piston valve opened when a predetermined temperature was sensed. When the ambient temperature receded to a safe level the pilot valve closed and pressure was allowed to build up in the control chamber to close the piston valve. It was desirable that the fluid passages be centrally located so that maximum supply line pressure is communicated to the control chamber to assure piston valve closure.

While the automatic shut ofi was considered a substantial advance in sprinkler systems, a new difficulty arose. Upon initial installation when first subjected to pressurized fluid, the sprinklers would all open for a period of time. After the pressure built up in the control chamber, the sprinklers would shut off. Likewise whenever the system was drained, the sprinklers would open when the system was again pressurized. U.S. Pat. No. 3,698,483 recognized the problem and suggested that a temporary clip or wedge be used to hold the valve closed during installation to prevent an immediate surge of water from opening the valves.

Since the sprinkler head was connected directly to the water supply line which was subjected to pressure fluctuations, difficulties were encountered. When the water pressure decreased gradually, the pressure in the control chamber followed rather closely and no difficulties were encountered. However, if a gradual decrease was followed by a sudden pressure increase, the pressure in the control chamber did not follow closely and the piston valve would open discharging fluid.

Because of this difficulty, approving authorities have established requirements for a fluctuating pressure test wherein the system pressure is increased and decreased rapidly. In an attempt to overcome this problem U.S. Pat. No. 3,702,160 discloses the use of a check valve to maintain the maximum pressure within the control chamber. The check valve consisted of a flap of resilient material having a large contact area covering an opening in a partition. This form of check valve could not be readily adapted to other types of sprinklers. The flap type check valve also had a tendency to stick especially if oil was present on the surface of the check valve. This sticking would have a tendency to prevent the valve from opening especially under the low pressure exerted thereon when the main sprinkler valve was open. As a result the automatic shut off provision could become inoperative if the valve stuck in a closed position.

SUMMARY OF THE INVENTION The present invention provides 'an improved ON- OFF sprinkler that is uneffected by surges in the fluid supply line. The sprinkler utilizes a line pressure operated piston valve slideably and sealingly disposed within a control chamber for closing a downstream end of a fluid inlet member which is adapted for connection to a fluid supply source. A fluid passage is formed through the center of the piston valve to communicate the supply line pressure to the control chamber. A centrally located tubular guide member is used for aligning the piston within the control chamber. The unique use of a centrally located tubular guide member allows the fluid passage to be centrally located so that the maxi mum line pressure is transmitted to the control chamber especially when the piston valve is open. The tubular guide member has an end inserted in a bore formed axially with the control chamber. The structure is particularly adaptable to the use of a ball type check valve disposed in the bore to close oneend of the,tu'btilar member for maintaining the line pressure in the control chamber and to prevent reverse fluid flow.

The unique combination of a bail type check valve and a tubular guide member provides several structural and operational advantages. A single centrally located guide is the simplest and least expensive form of guide member. Since the guide is tubular it allows for the central location of a passage through the piston valve. The centrally located passage assures the transmittal of maximum line pressure to the control chamber when the piston valve is open. An ofl centered passage would not receive the full force of the discharged fluid and maximum pressure would not be transmitted to the control chamber. The ball type check valve is easily disposed in the bore so as to rest on the end of the tubular guide. The ball is not subject to sticking and provides a reliable check valve.

The use of a check valve allows for the preloading of the control chamber and eliminates the need for the clips or wedges used in the prior art. The sprinklers can be preloaded so that the system can be turned on without fear of having the sprinkler accidently discharge fluid. The system can be drained and repressurized without leakage. More importantly, once the system is pressurized the sprinklers are uneffected by line pressure fluctuations.

It is the primary objective of the present invention to provide a sprinkler that is uneffected by pressure surges in the water supply line.

Another objective of the present invention is to provide a simplified guide member that provides for the central location of a fluid passage to the control chamber.

Another objective of the present invention is to provide a sprinkler having a unidirectional check valve to permit flow of fluid into the control chamber while preventing the reverse flow.

Another objective of the present invention is to provide a sprinkler having a unidirectional check valve that is not subject to sticking.

The foregoing and other objects and advantages of the present invention will become more apparent from the following description and the accompanying drawings wherein one embodiment of the present invention is described.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of the present invention shown partially in section taken along line l-l of FIG. 2. i v

' FIG. 2 is a side elevation of the present invention shown partially in section taken along line 2--2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there is shown an embodiment of the automatic sprinkler of the present invention. A lower body portion formed of a non-ferrous material such as bronze includes a fluid inlet member 11 having an upstream end 12 and a downstream end 14. The upstream end includes a threaded portion 16 for coupling to a source of pressurized fire extinguishing fluid. The downstream end 14 includes a valve means 18 having an annular groove 20 formed therein for receiving an .O-ring 22 preferably formed of silicone rubber. The

lower body portion includes an open frame, formed by a pairof outwardly and upwardly extending arms 24, to which an upper body portion 26 is mounted by a pair of screws28. The upper body portion 26 is formed of a non-ferrous material and is preferably cast from bronze while the screws 28 are brass.

A cylindrical control chamber 30 is formed within the upper body portion 26 and has an open end facing the downstream end 14 of the fluid inlet member and spaced therefrom. The cylindrical control chamber is formed in axial alignment with the fluid inlet member. A bore 32 is also formed in the upper body portion and is axially aligned with the cylindrical control chamber.

A piston valve 34 is formed of machined brass and has a piston portion 36 including an outer cylindrical surface 38 disposed within the cylindrical control chamber for reciprocation therein. Cylindrical surface 38 has a peripheral groove 40 formedtherein forreceiving an O-ring 42 which prevents fluid flow through the space between the wall of cylindrical control chamber 30 and the cylindrical surface 38. A valve portion 44 is formed on the lower end of piston valve 34 and includes a flat annular surface 46 which cooperates with 0-ring 22 for closing the downstream end 14 of the fluid inlet member. A brass fluid deflector 48 is also mounted about the lower end of valve portion 44 for establishing a predetermined pattern for the discharged fluid.

A tubular guide member 50 is mounted to the piston valve 34 and is positioned axially therewith so that one end of the guide member extends into bore 32. The guide member is preferably formed of a non-ferrous material such as brass and functions to align and guide the piston valve during reciprocation in the cylindrical control chamber 30. A coil spring 52 formed of a nonferrous material is disposed about the tubular guide member 50 and is seated at one end within a recess 54 formed in the piston valve 34. Spring 52 provides a resilient bias to the piston valve and urges the valve towards a closed position. A fluid passage 56 is formed through the piston valve 34 and is centrally positioned so as to communicate with the hollow interior of the tubular guide memberSO and the donwstream end of the fluid inlet member. A domed shaped brass strainer 58 is'positioned to cover the inlet of passage 56 and is held in place by a retaining ring 60 which is press fit into the valve portion of the piston valve 34.

A stainless steel ball 62 is disposed within bore 32 and rests on the end of the tubular guide member 50 to form a unidirectional check valve and to prevent reverse flow of fire extinguishing fluid through the tubular guide member.

A temperature responsive pilot valve assembly 64 is mounted in a pilot valve chamber 66 formed within the upper body portion 26. A passage 68 connects the cylindrical control chamber 30 with the pilot valve chamber 66 and an outlet port 70 is formed in the upper body portion 26 for communicating the pilot valve chamber with atmosphere.

The pilot valve assembly 64 comprises a retainer member 72 formed of sintered brass or bronze and having threaded portion 74 for engaging a threaded portion of the pilot valve chamber 66. The retainer member 72 has a radial flanged portion 76 which is positioned a short distance from the upper body portion 26 when the retainer member is threaded into the pilot valve chamber. i

A bore 78 extends axially through the retainer member for receiving a cylindrical portion 80 of a pilot valve 82. Pilot valve 82 is mounted for reciprocation within bore 78 and cylindrical portion 80 has a groove 84 formed therein for receiving a O-ring 86 which forms a seal between the cylindrical portion 80 and the bore 78.

A valve seating surface 88 is formed about the outlet port 70 for cooperation with a valve means 90 formed on an inner end of the pilot valve 82. Valve means 90 comprises a silicone rubber O-ring 92 disposed within a groove 94 formed on the inner end of the valve 82.

A bimetallic disc 96 is centrally connected to the outer end of valve 82 by a drive screw 98 which passes through a central opening in the disc 96 and into a drilled hole at the outer end of valve 82. The edges of disc 96 are secured to theradial flange 76 by drive screws 100 Preferably the area of contact of the drive screws with the bimetallic disc is heldto a minimum so that the heat flow from the bimetallic discto the flange is held at a minimum.

The bimetallic disc is cupped and is designed to move with a snap action toward a reverse cup shape at a predetermined temperature, for example 185 F, and when in the reverse shape to return towards the original shape at a second lower temperature for example 100 F. Further, the bimetallic disc is positioned with its convex surface facing the pilot valve and is urged against the valve to resiliently bias the valve toward its closed position.

Since the fluid used is usually water, it is preferred that all the components be non-ferrous or stainless steel. While brass and bronze are preferred, other materials could also be used.

In operation, the sprinkler is installed in a sprinkler system in an upright position and the fluid inlet member 11 is coupled to a source of pressurized fire extinguishing fluid such as water. The fluid source must be turned on slowly to allow the control chamber pressure to follow the line pressure. When the source is turned on, the fluid flows through inlet member 11, strainer 58, passage 56, tubular guide member 50, bore 32 and into control chamber 30. The pilot valve 82 is held in a closed position by the resilient force of the bimetallic disc 96 and pressure is allowed to build up within the control chamber. After a short period of time, the fluid pressure is equalized above and below the piston valve. If a check valve such as ball 62 is used, the control chamber 30 may be preloaded with pressurized fluid prior to installation in the system. In such a case, the line pressure can be fully applied without fear of the sprinkler valve opening.

The effective area of the piston 36 exposed to the pressure within the control chamber is greater than the area of the valve means 44 exposed to the pressure within the fluid inlet member so that when the pressure within the control chamber equals the pressure within the fluid inlet member a differential force is established which holds the valve 44 in a closed position.

In the event of a tire, the ambient temperature surrounding the bimetallic disc will rise and when it reaches the operating temperature of thedisc thedisc snaps to a reverse cup shape moving the pilot valve with it and thereby opening the outlet port and releasing the pressure from the control chamber.

When the pressure within the control chamber is reduced, the force established by the pressure of the inlet fluid on the valve means 44 exceeds the force of the chamber pressure on piston 36 and the force of spring 52. The piston valve then moves in an upwardly direction opening the downstream end of the fluid inlet member. The fluid flows through the downstream end of the fluid inlet member and is discharged against the deflector 48 until the fire is extinguished.

After the fire is extinguished and the ambient temperature cools to a normal level, the bimetallic disc snaps to its original position thereby closing the outlet port 70 and allowing pressure to build up within the control chamber 30. The fluid discharging against the valve means 44 partially flows through passage 56 and increases the pressure within the control chamber 30 until it equals the fluid inlet pressure at which time the force produced by the pressure within chamber 30 will be sufficient to force the piston valve to the closed posi- 6 tion thereby stopping the discharge of fire extinguishing fluid.

The use of a check valve prevents the unintentional opening of the sprinkler as a result of erratic fluid source pressure variations. The check valve assures that a maximum pressure is maintained within the control chamber so that intermittent pressure surges do not cause the valve to open. Additionally, the ball check valve permits preloading of the control chamber with fluid to substantially eliminate the possibility of fluid leakage during the initial turning on of the system. Prior art devices required the use of a wedge to hold the valves closed until the system was fully pressurized after which time the wedges had to be removed. This operation was time consuming and was performed at great expenses. The use of a ball type check valve provides for smooth non-sticking valve operation and thereby provides a sprinkler with greater sensitivity. The use of a check valve also allows the system to be periodically drained and refilled without fear of the sprinkler opening.

It is tobe noted that the piston portion of the piston valve is relatively thin so as to reduce the amount of material required and the overall size of the sprinkler head. Thin pistons have a tendency to become misaligned and to jam within the control chamber; therefore, a guide member is essential to properly align the piston within the control chamber. The least complex and most effective form of guide member is a single guide centrally located. It is also desirable that the fluid passage through the piston be centrally so that the maximum fluid pressure is transmitted to the control chamber when the valve is open. These two desirable structural features, namely, a centrally located guide and a centrally located passage, can only be realized by the unique use of a tubular guide member which provides both a centrally located guide and a centrally positioned fluid passage.

The valve structures taught by the prior art could not readily be used with the tubular guide member; however, a ball type check valve used in combination with a centrally positioned fluid passage and tubular guide member provides an, inexpensive and reliable check valve.

Thus, the present invention provides an automatic sprinkler that is uneffected by pressure surges in the fluid source. The sprinkler has a centrally located fluid passage for maximum transmittal of line pressure to the control chamber. The unidirectional check valve allows for preloading of the control chamber so that the on site installation time is reduced and the possibility of accidental sprinkler operation is greatly reduced.

While the principles of the invention have been described in connection with a specific structure, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

l. A water sprinkler for a fire protection sprinkler system, comprising:

a body member including a fluid inlet means adapted for coupling to a source of pressurized fluid;

a cylindrical control chamber formed in said body member in axial alignment with the fluid inlet means;

piston means slideably and sealingly disposed in said control chamber;

valve means associated with the piston'means for opening and closing the fluid inlet means in response to the position of said piston means in the control chamber; 7

means formed in said body member for discharging fluid when the fluid inlet means is open;

a cylindrical bore formed in said body member in axial alignment with the control chamber and in communication therewith;

a tubular guide member mounted axially in said piston and having an end extending partially into the cylindrical bore for guiding the piston during reciprocation in the control chamber,-said tubular guide member loosely fitting in said bore;

a passage formed substantially centrally in said piston communicating the fluid inlet means with the tubular guide member, so that pressurized fluid is coupled from the fluid inlet means to the control chamber through a conduit formed by the passage, tubular guide member and'the cylindrical bore, the effective area of the piston exposed to the pressure in the control chamber being greater than the effective area of the valve means exposed to pressure in said fluid inlet means, so that the piston is urged towards the fluid inlet means and the valve means closes the fluid inlet means;

a ball type check valve means disposed in the conduit for preventing fluid flow from the control chamber to the fluid inlet means while allowing pressurized fluid to flow into the control chamber;

an outlet port formed in said body member for releasing fluid from the control chamber; and

temperature responsive pilot valve means associated with said outlet port for controlling fluid. flow through the outlet port in response to ambient temperature so that the pressure in the control chamher is released when a predetermined ambient temperature is attained and the piston is urged away from the fluid inlet means by the force of the pressurized fluid thereby opening the fluid inlet means for discharging the pressurized fluid.

V 2. A water sprinkler as described inclaim I, wherein said body member comprises:

a fluid inlet member having a downstream end and an upstream end adapted for coupling to a source of pressurized fluid;

an open frame associated with said inlet member; and

an upper body portion supported by said framein spaced relation to said downstream end, said cylindrical control chamber formed in the upper body portion and having an open end facing said downstream end and spaced therefrom.

3. A water sprinkler as described in claim 2, wherein the open frame comprises a pair of arms extending upwardly and outwardly from the inlet member.

4. A water sprinkler as described in claim 2, wherein the valve means is formed integrally with the piston means and engages a valve seating surface about the downstream end of the fluid inlet member.

5. A water sprinkler as described in claim 4, additionally comprising deflector means mounted on said valve means for distributing pressurized fluid through said open frame when the downstream end of the fluid inlet LII member is open. I I

system, comprising: I

a fluid inlet member having an upstream end adapted for coupling to a source of pressurized fluid and a downstream end;

an open frame associated with said inlet member;

a body member supported by said open frame in spaced relationship to said downstream end, said body member having a cylindrical control chamber formed therein in axial alignment with the fluid inlet member and having an open end facing said downstream end and spaced therefrom;

piston means slideably and sealingly disposed in said control chamber for closing and sealing said chamber; 1

valve means for opening and closing the downstream end of the fluid inlet member in response to the position of said piston in the control chamber;

deflector means mounted on said piston for distributing pressurized fluid through said open frame when the downstream end of the fluid inlet member is open; I

a cylindrical bore formed in said body member concentric with the control chamber and in communication therewith;

a tubular guide member mounted axially in said piston and having an end extending partially into the cylindrical bore for guiding the piston during reciprocation in the control chamber, said tubular guide member loosely fitting in said bore;

a passage formed substantiallycentrally through said piston communicating the fluid inlet member with the tubular guide member, so that pressurized fluid is coupled from the fluid inlet member to the control chamber through the passage, tubular guide member and the cylindrical bore, the effective area of the piston exposed to the pressure in the control chamber being greater than the effective area of the valve means exposed to pressure in said fluid inlet member, whereby the piston is urged towards the fluid inlet member and the valve means closes the downstream end of the fluid inlet member;

a ball disposed in the bore and adapted to rest on the end of the tubular member extending into the bore for preventing fluid flow from the control chamber to the inlet member while allowing pressurized fluid to flowinto the control chamber;

an outlet port formed in said body member for releasing fluid pressure from the control chamber; and

temperature responsive pilot valve means associated with said outlet port for controlling fluid flow through the outlet port in response to ambient temperature so that the pressure in the control cham ber is released when a predetermined ambient temperature is attained and the piston is urged away from the fluid inlet member by the force of the pressurized fluid thereby opening the downstream end of the fluid inlet member for distribution of the pressurized fluid.

7. A water sprinkler as described in claim 1, wherein the ball type check valve means comprises a ball disposed in the bore and adapted to rest on the endof the tubular member extending into the bore.

Claims

1. A water sprinkler for a fire protection sprinkler system, comprising: a body member including a fluid inlet means adapted for coupling to a source of pressurized fluid; a cylindrical control chamber formed in said body member in axial alignment with the fluid inlet means; piston means slideably and sealingly disposed in said control chamber; valve means associated with the piston means for opening and closing the fluid inlet means in response to the position of said piston means in the control chamber; means formed in said body member for discharging fluid when the fluid inlet means is open; a cylindrical bore formed in said body member in axial alignment with the control chamber and in communication therewith; a tubular guide member mounted axially in said piston and having an end extending partially into the cylindrical bore for guiding the piston during reciprocation in the control chamber, said tubular guide member loosely fitting in said bore; a passage formed substantially centrally in said piston communicating the fluid inlet means with the tubular guide member, so that pressurized fluid is coupled from the fluid inlet means to the control chamber through a conduit formed by the passage, tubular guide member and the cylindrical bore, the effective area of the piston exposed to the pressure in the control chamber being greater than the effective area of the valve means exposed to pressure in said fluid inlet means, so that the piston is urged towards the fluid inlet means and the valve means closes the fluid inlet means; a ball type check valve means disposed in the conduit for preventing fluid flow from the control chamber to the fluid inlet means while allowing pressurized fluid to flow into the control chamber; an outlet port formed in said body member for releasing fluid from the control chamber; and temperature responsive pilot valve means associated with said outlet port for controlling fluid flow through the outlet port in response to ambient temperature so that the pressure in the control chamber is released when a predetermined ambient temperature is attained and the piston is urged away from the fluid inlet means by the force of the pressurized fluid thereby opening the fluid inlet means for discharging the pressurized fluid.

2. A water sprinkler as described in claim 1, wherein said body member comprises: a fluid inlet member having a downstream end and an upstream end adapted for coupling to a source of pressurized fluid; an open frame associated with said inlet member; and an upper body portion supported by said frame in spaced relAtion to said downstream end, said cylindrical control chamber formed in the upper body portion and having an open end facing said downstream end and spaced therefrom.

5. A water sprinkler as described in claim 4, additionally comprising deflector means mounted on said valve means for distributing pressurized fluid through said open frame when the downstream end of the fluid inlet member is open.

6. A water sprinkler for a fire protection sprinkler system, comprising: a fluid inlet member having an upstream end adapted for coupling to a source of pressurized fluid and a downstream end; an open frame associated with said inlet member; a body member supported by said open frame in spaced relationship to said downstream end, said body member having a cylindrical control chamber formed therein in axial alignment with the fluid inlet member and having an open end facing said downstream end and spaced therefrom; piston means slideably and sealingly disposed in said control chamber for closing and sealing said chamber; valve means for opening and closing the downstream end of the fluid inlet member in response to the position of said piston in the control chamber; deflector means mounted on said piston for distributing pressurized fluid through said open frame when the downstream end of the fluid inlet member is open; a cylindrical bore formed in said body member concentric with the control chamber and in communication therewith; a tubular guide member mounted axially in said piston and having an end extending partially into the cylindrical bore for guiding the piston during reciprocation in the control chamber, said tubular guide member loosely fitting in said bore; a passage formed substantially centrally through said piston communicating the fluid inlet member with the tubular guide member, so that pressurized fluid is coupled from the fluid inlet member to the control chamber through the passage, tubular guide member and the cylindrical bore, the effective area of the piston exposed to the pressure in the control chamber being greater than the effective area of the valve means exposed to pressure in said fluid inlet member, whereby the piston is urged towards the fluid inlet member and the valve means closes the downstream end of the fluid inlet member; a ball disposed in the bore and adapted to rest on the end of the tubular member extending into the bore for preventing fluid flow from the control chamber to the inlet member while allowing pressurized fluid to flow into the control chamber; an outlet port formed in said body member for releasing fluid pressure from the control chamber; and temperature responsive pilot valve means associated with said outlet port for controlling fluid flow through the outlet port in response to ambient temperature so that the pressure in the control chamber is released when a predetermined ambient temperature is attained and the piston is urged away from the fluid inlet member by the force of the pressurized fluid thereby opening the downstream end of the fluid inlet member for distribution of the pressurized fluid.

7. A water sprinkler as described in claim 1, wherein the ball type check valve means comprises a ball disposed in the bore and adapted to rest on the end of the tubular member extending into the bore.