On-off Fire Sprinkler

Abstract

Disclosed in a fire sprinkler having a valve body that defines inlet and outlet openings joined by a flow passage possessing a valve seat. A valve head is movable relative to the valve seat between open and closed positions by either a primary condition responsive actuator or an auxiliary condition responsive actuator. In response to a given condition associated with the generation of combustion products, for example, a given ambient temperature, the primary actuator first causes an operator mechanism to open the valve and then after cessation of the given condition induces reclosing thereof. The auxiliary actuator causes the operator mechanism to permanently open the valve in response to a different, more serious condition such as a higher ambient temperature.

Description

This invention relates generally to fire sprinklers and, more particularly, to a fail-safe fire sprinkler head having an on-off control mechanism.

Most conventional fire sprinklers employ discrete closure elements that seal a discharge orifice and are maintained in position by a releasable toggle mechanism restrained by a body of eutectic material. In response to a temperature rise accompanying fire the eutectic material melts releasing the toggle mechanism and allowing the closure element to be forcibly discharged from the sprinkler head. Such sprinklers are simply constructed and extremely reliable in operation. However, once opened, they remain open to frequently produce discharge of large quantities of water even after a fire has been suppressed. This excess water flow often causes greater damage than the fire itself. In addition, the continuous uncontrolled flow of water from a plurality of opened sprinkler heads can so reduce line pressure that water is unavailable when needed at other sprinklers in the system.

Also known are so called "on-off" fire sprinklers embodying controlled actuators that open a valve in response to ambient temperatures above a given level and close the valve in response to a decrease in ambient temperature to below that level. The obvious object of such valves is to prevent continuous and uncontrolled flow of water after initial actuation and thereby alleviate the problem described above. However, the utilization of an on-off controller somewhat diminishes reliability which is so essential to fire protection systems both from the standpoint of safety and compliance with requirements of insurance carriers.

The object of this invention, therefore, is to provide a fire sprinkler that prevents indiscriminate and wasteful discharge of extinguishent while also being extremely reliable in its operation.

SUMMARY OF THE INVENTION

The invention is characterized by the provision of a fire sprinkler having a valve body that defines inlet and outlet openings joined by a flow passage possessing a valve seat. A valve head is movable relative to the valve seat between open and closed positions by either a primary condition responsive actuator or an auxiliary condition responsive actuator. In response to a given condition associated with the generation of combustion products, for example, a given ambient temperature, the primary actuator first causes an operator mechanism to open the valve and then after cessation of the given condition induces reclosing thereof. The auxiliary actuator causes the operator mechanism to permanently open the valve in response to a different, more serious condition such as a higher ambient temperature. Thus, the primary actuator normally provides on-off valve control that prevents indiscriminate, continuous flow of water while the auxiliary actuator enhances reliability by overriding the primary actuator in the event that it fails to function for any reason.

In a preferred embodiment of the invention, the primary actuator comprises a substance that controls valve operation by experiencing a substantial change in volume at a critical temperature and the auxiliary actuator comprises an eutectic material that melts at a higher critical temperature. Preferably, valve operation is controlled by a pilot volume communicating with the valve inlet and vented in response to sensing by either primary or auxiliary actuator of its critical temperature.

One feature of the invention is an auxiliary actuator comprising a release mechanism for venting the valve controlling pilot volume. The release mechanism includes a cup-shaped, metalic primary seal member having cylindrical walls hermetically sealed by a fusible metallic alloy to the internal walls of a tube communicating with the pilot volume. An auxiliary seal is formed by an oppositely oriented resilient cup-shaped member disposed within the tube between the primary sealing plug and the pilot volume. Upon initial creation of a leak path through the alloy, the fluid pressure within the pilot volume forces the cylindrical side wall of the auxiliary seal into sealing contact with the tube while the fluid pressure exerted on the end wall of the auxiliary seal member is retained by the oppositely disposed end wall of the primary seal plug. However, after complete fusing of the eutectic material to release the metal seal plug, the internal pressure of the pilot volume acts to dislodge both seal members from the tube and vent the pilot volume.

DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will become more apparent upon a perusal of the following description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a cross sectional view of a preferred fire sprinkler embodiment of the invention; and

FIG. 2 is a cross sectional drawing taken along lines 2--2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the Figures there is shown a sprinkler head formed by a valve body 2 that defines an inlet opening 3 and an outlet opening 4. Extending below the body 12 so as to deflect fluid discharged through the outlet 4 is a deflector 5. A flange 6 on the valve body 2 accommodates a mating flange 7 of an inlet tube 8 threaded for connection to a source of pressurized fluid. The tube 8 communicates with the inlet opening 3. An annular holding ring 10 is crimped over the flanges 6 and 7 which retain an O-ring gasket 11.

Also defined by the valve body 2 is a passage 12 that provides fluid communication between the inlet 3 and the outlet 4 and a valve seat 13 adjacent thereto. A central bore 15 in the valve body 2 guides movement of a valve head 16 within the passage 12. Fixed on the head 16 is a gasket 20 that is forced into seating engagement with the valve seat 13 by a spring 9. An O-ring 17 is retained between the surface of the bore 15 and an annular external groove in the valve head 16. Provided within the valve head 16 is a central recess 18 that partially defines with the unoccupied portion of the bore 15 an operator pilot volume 19. Also included in the pilot volume 19 is a transverse bore 21 that communicates with the central bore 15 through an orifice 22. Other orifices 23 through the valve head 16 provide limited fluid communication between the flow passage 12 and the pilot volume 19.

Disposed within the transverse bore 21 is a primary condition responsive actuator 31 that vents the pilot volume 19 through a vent orifice 32 in response to a given condition associated with the release of combustion products. Included in the actuator 31 is a ball valve 33 that is retained in closed position over a valve opening 34 by a bias spring 35 that abuts against a retainer ring 36 in the transverse bore 21. Preferably, the primary actuator 31 includes as an active element a thermally responsive actuator 37 that screws into the valve body 2 and controls movement of a piston 38. The actuator 37 can be the type which retains a wax material that when subjected to a given temperature changes from solid to liquid form undergoing a substantial increase in volume that ejects the piston member 38. Actuators of this type are disclosed, for example, in U.S. Patent Nos. 2,815,174 & 2,938,384.

An auxiliary condition responsive release mechanism 41 comprises a cup-shaped sealing plug 42 and an oppositely oriented cup-shaped auxiliary seal element 43. The plug 42 possesses an end wall 44 that closes a tube 40 inserted into the transverse bore 21. A cylindrical side wall 45 of the plug 42 is hermetically sealed to the inner surface of the tube 40 by an eutectic material 46 such as a metallic alloy that fuses at a temperature above that required to melt the wax in the actuator 37. The auxiliary seal element 43, preferably made of a resilient elastomeric material, similarly includes an end wall 47 in contact with the end wall 44 of plug 42 and a cylindrical side wall 48 the outer surface of which engages the inner surface of the tube 40.

During use, the sprinkler head of the present invention is mounted in any location for which fire protection is desired and the tubulation 8 is connected to a source of water or other suitable fire extinguishing fluid. Resultant line pressure in the passage 12 is transmitted through the pilot openings 23 to the pilot volume 19 which is sealed by the ball valve 33 and the unbroken seals in the auxiliary actuator 41. Since the total area of the valve head 16 exposed to the line pressure existing within the pilot volume 19 is substantially greater than the peripheral area 51 exposed to line pressure in the passage 12, the gasket 20 is retained in tight sealing engagement with the valve seat 13 preventing discharge of fluid through the outlet opening 4. However, in response to an increase in ambient temperature that would typically accompany the existence of fire, the wax in primary actuator 37 melts and increases in volume ejecting the piston 38 and forcing the ball valve 33 out of the opening 34. This permits release of line pressure in the pilot volume 19 through the vent opening 32 which provides substantially more conduction than do the pilot openings 23. After the reduction of pressure in the pilot volume 19, the higher pressure in passage 12 exerts a sufficient force on the peripheral area 51 to move the valve head 16 away from the seat 13 thereby allowing discharge of extinguishing fluid through the outlet opening 4. Assuming that subsequently, the initiating condition is controlled to the extent that ambient temperature falls below the melting temperature of the wax in the primary actuator 37, it resolidifies and decreases in volume allowing the bias spring member 35 to force the ball valve 33 back into a closed position over the opening 34. With the vent opening 32 closed, line pressure is again re-established in the pilot volume 19 through the pilot orifices 23 and the valve head 16 again moved into closed position sealing the gasket 20 against the valve seat 13. If environmental conditions change to again produce the critical ambient temperature, the above operation will be repeated to open the valve and provide discharge of extinguishing fluid. Thus, the operation of the valve is continuously cycled between open and closed positions in response to corresponding changes in the ambient temperature sensed by the wax actuator 37.

Assume next that for any reason the primary condition responsive actuator 31 fails to operate due to a malfunction of any of its components. A fail-safe feature of the invention is then provided by the auxiliary actuator 41 which operates as follows. When the ambient temperature in the protected volume rises to above its fusing temperature the eutectic material 46 begins to melt. Typically, this melting process is not uniform because of localized variations in the temperature to which the material 46 is subjected and also due to some non-uniformity in the temperature response of the material itself. For these reasons, isolated leaks are generally created through the annularly distributed eutectic material 46 before it is completely melted to release the plug 42. The prmature fluid flow through these leak paths from the volume 19 is prevented by the auxiliary seal member 43. Accordingly, localized cooling of the eutectic material 46 by escaping fluid is prevented and the entire body of mateial 46 is quickly melted to release the plug 42. This melting process is further enhanced by the cup-shape of the plug 42 which minimizes the thermal mass in contact with the eutectic matrial 46. Correspondingly, the shape and resiliency of the auxiliary seal 43 enhances its sealing function. The fluid pressure within the tube 40 forces the resilient outer surface of the side wall 48 against the internal surface of the tube 40 thereby providing a substantial fluid seal therebetween. However, upon complete melting of the eutectic material 46, the internal fluid pressure exerted against the end wall 47 forces both the auxiliary seal member 43 the auxiliary seal member 43 and the plug 42 out of the tube 40. This vents the pilot volume 19 and induces opening of the valve 16 as described above. Thus, in the event that primary actuator 31 fails to function, operation is insured by the auxiliary actuator 41.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example only, actuators and fluid extinguishing media other than those specifically described can be used. It is to be understood, therefore, that the invention can be practiced otherwise than as specifically described.

Claims

What is claimed is:

1. A fire sprinkler comprising:

a valve body means defining an inlet opening, an outlet opening, a fluid flow passage between said inlet and outlet openings, and a valve seat disposed in said fluid flow passage;

a valve head movable between a closed position engaging said valve seat and an open position separated therefrom, said valve head preventing fluid flow between said inlet and outlet openings when in said closed position and allowing fluid flow therebetween when in said open position;

a primary condition responsive actuator means for inducing movement of said valve head from said closed to said open position in response to a given condition associated with the generation of combustion products; and

an auxiliary condition responsive actuator means for inducing movement of said valve head from said closed to said open position in response to a different condition associated with the generation of combustion products.

2. A fire sprinkler according to claim 1 wherein said primary actuator means comprises control means adapted to induce said movement of said valve head, said control means comprising bias means for inducing return of said valve head to said closed position after a cessation of said given condition.

3. A fire sprinkler according to claim 1 wherein said primary and auxiliary actuator means are thermally responsive, said given condition is a given ambient temperature, and said different condition is a different ambient temperature greater than said given temperature.

4. A fire sprinkler according to claim 3 wherein said primary actuator means comprises a substance that induces said movement of said valve head by experiencing a substantial change in volume at said given temperature, and said auxiliary actuator means comprises a eutectic material that melts at said different temperature.

5. A fire sprinkler according to claim 4 wherein said substance experiences a change between solid and liquid states at said given temperature.

6. A fire sprinkler according to claim 1 including operator means operatively coupled to both said primary and auxiliary actuator means and responsive thereto to induce said movement of said valve head.

7. A fire sprinkler according to claim 6 wherein said operator means comprises a pilot volume that provides a pressure tending to move said valve head to closed position, and wherein said primary and auxiliary actuator means are adapted to reduce the pressure in said pilot volume in response to said given and different conditions.

8. A fire sprinkler according to claim 7 wherein said primary actuator means comprises control means for inducing an increase in pressure within said pilot volume after a cessation of said given condition.

9. A fire sprinkler according to claim 8 wherein said primary and auxiliary actuator means are thermally responsive, said given condition is a given ambient temperature, and said different condition is a different ambient temperature greater than said given temperature.

10. A fire sprinkler according to claim 9 wherein said auxiliary actuator means comprises a vent orifice for accomodating release of fluid pressure from said pilot volume, temperature responsive hermetic seal means sealing said vent orifice, said hermetic seal means comprising an eutectic material adapted to melt at said different temperature, and auxiliary seal means isolating said eutectic material from the pressurized fluid in said pilot volume.

11. A fire sprinkler according to claim 10 wherein said auxiliary seal means comprises a pressure responsive portion adapted to be automatically opened by the fluid pressure in said pilot volume in response to opening of said hermetic seal means.

12. A fire sprinkler according to claim 11 wherein said pressure responsive portion is retained in sealing position by said hermetic seal means.

13. A fire sprinkler according to claim 12 wherein said auxiliary actuator means comprises a tube with an open end forming said vent orifice, said auxiliary seal means comprises a resilient cup having a cylindrical side wall portion engaging an internal wall of said tube and an end wall forming said pressure responsive portion.

14. A fire sprinkler according to claim 13 wherein said hermetic seal means further comprises a cup-shaped plug disposed in said tube and having an end wall engaging said resilient cup end wall and a cylindrical side wall hermetically sealed to said internal wall of said tube by said eutectic material.