Claims
- 1. A valve assembly for use in automatic fire extinguishing systems and comprising:
- a housing means defining inlet and outlet openings;
- a valve member movable between closed and open positions, said valve member preventing fluid flow between said inlet and outlet openings when in said closed position and permitting the discharge of fluid available at said inlet opening through said outlet opening when in said open position;
- actuator means for moving said valve member between said open and closed positions;
- primary temperature responsive control means operatively coupled to said actuator means for automatically effecting movement of said valve member to said open position in response to ambient temperatures above a given level; and
- auxiliary temperature responsive control means operatively coupled to said actuator means and operative to automatically effect movement of said valve member to said closed position in response to an ambient temperature below said given level occurring subsequently to opening of said valve member by said primary control means.
- 2. A valve assembly according to claim 2 wherein said primary temperature responsive control means comprises a primary mechanism that experiences a mechanical deformation when subjected to temperatures above said given level, and said auxiliary temperature responsive control means comprises an auxiliary mechanism that experiences a mechanical deformation when subjected to temperature above a second level less than said given level.
- 3. A valve assembly according to claim 2 wherein said primary mechanism experiences reversible deformations when subjected to temperatures above or below said given level, and said auxiliary mechanism experiences reversible deformations when subjected to temperatures above or below said second level.
- 4. A valve assembly according to claim 3 wherein each of said primary and auxiliary mechanisms comprise bodies of expansible material of a type that experiences substantial volume changes between solid and liquid states, said changes of state being induced by changes in temperature.
- 5. A valve assembly according to claim 2 wherein said auxiliary temperature responsive control means comprises latching means responsive to said auxiliary mechanism for latching said valve member in said open position at ambient temperature above said second level.
- 6. A valve assembly according to claim 5 wherein said primary temperature responsive control means comprises biasing means opposing movement of said valve member to said open position.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a division of U.S. Application Ser. No. 399,851, filed Sept. 24, 1973, and entitled "Delayed Closing Fire Sprinkler Heads" now U.S. Pat. No. 3,911,940 which was in turn a continuation-in-part of U.S. Application Ser. No. 143,394, filed May 14, 1971, and entitled "Automatic Fire Sprinkler Head" which issued on Apr. 9, 1974, as U.S. Pat. No. 3,802,510.
This invention relates generally to valves and, more particularly, to automatically opening and closing temperature responsive valves for use in fire extinguishing systems.
Automatic fire extinguishing systems are useful for quickly extinguishing or controlling fires. The general acceptance of such systems is evidenced by their extensive use in commercial buildings such as factories, office buildings, apartment houses, stores, etc. In addition, their use has expanded recently for the protection of homes in residential areas. Conventional systems usually include a plurality of individual valve and nozzle combinations, with each valve independently controlled by a thermally fusible element. With independently controlled valves only those nozzles subject to heat produced by a fire are activated, rather than the entire system. Therefore, water damage does not occur in areas remote from the fire. Conventional fire valves, however, being of the "one-shot" type do not automatically close and reset so that water continues to flow after a fire is extinguished unless the water supply to the building is manually shut off. For this reason, water is wasted, and unnecessary water damage in the area of the fire results. A typical example would be a grease fire confined to a single pan and quickly extinguished by merely placing a cover over the pan. If, however, a "one-shot" fire valve in the kitchen had been activated by the heat generated before extinguishment, water would continue to flow needlessly until the water supply was turned off at the source.
Valves that automatically close and reset upon cooling have been proposed to alleviate the problems discussed above. However, one problem associated with many such valves stems from their sensitivity to a given critical actuation temperature. Because of this sensitivity the valve can in some cases rapidly cycle between open and closed positions in response to temperature fluctuating around the critical actuation temperature. Such rapid cycling can be disadvantageous in certain applications in which a longer or more predictable on-time is desired.
The object of this invention, therefore, is to provide an on-off fire sprinkler valve in which on-time is controlled to provide greater predictability of operation.
One feature of the invention is the utilization of a primary temperature responsive control mechanism comprising a body of expansible fusible crystalline material. This material is characterized by a sharply defined melting point and a substantial increase in volume during the solid-to-liquid transition. The change in volume is used to mechanically control the valve member which is small in size and quickly and fully open when the ambient temperature reaches the melting point. Subsequently, as the ambient temperature declines, a substantial volume decrease occurs in the expansible material during a liquid-to-solid transition. The valve is then closed by a bias spring that opposes the expansion-induced opening. Thus, the flow of water is automatically stopped after the fire is extinguished, and the valve can be recycled at any time.
One embodiment of the invention employs an auxiliary control that moves a thermal shield over the melted material upon opening of the valve. The shield functions to retard cooling of the material and thereby delay reclosing of the valve.
Another embodiment of the invention includes as an auxiliary control a second temperature responsive actuator that allows the valve to open but prevents its closure with ambient temperature above a certain level. The second actuator responds to a lower temperature than the primary actuator and therefore provides a temperature delay for reclosure that insures full extinguishment of the fire.
US Referenced Citations (3)
Divisions (1)
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Number |
Date |
Country |
| Parent |
399851 |
Sep 1973 |
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Continuation in Parts (1)
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Number |
Date |
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| Parent |
143394 |
May 1971 |
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Patent Grant
3991829
