FIRE SAFETY SYSTEMS
United States Patent 3884304
Conventional water sprinkler heads, mounted in separate rooms, are set off by smoke detectors respectively mounted in the same rooms. A sprinkler head is set off by connecting a resistance wire coil across an electric potential. The heat generated melts the fusible link of the sprinkler head to discharge water therefrom. The coil is resilient to position it on the sprinkler head and is incorporated into a removable probe so that it may be replaced when desired. At a remote nurse's station, a set of lights indicates system readiness and also when one or more sprinklers has been set off. Manually operated switches, at the nurse's station, permit selected resistance coils to be energized to set off other sprinkler heads. A hallway smoke detector also provides an alarm at the nurse's station to alert an attendant to the possible need for remotely actuating selected sprinkler heads or all sprinkler heads by closing a "gang" switch which is also provided.
Inventors:
Messerschmidt, Robert P. (Loveland, OH)
Montag, Lloyd D. (Milford, OH)
Montag, Lloyd D. (Milford, OH)
Application Number:
05/274817
Publication Date:
05/20/1975
Filing Date:
07/24/1972
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
340/628, 169/42, 340/517
International Classes:
A62C35/60; G08B17/00; A62C35/58; G08B13/22
Field of Search:
8B/1706 340/418,222 169/1B,1R,20
Primary Examiner:
Habecker, Thomas B.
Attorney, Agent or Firm:
Lee III, Edmund S.
Claims:
Having thus described the invention, what is claimed as novel and desired to be secured by Letters Patent of the United States is
1. A fire safety system comprising:
2. A fire safety system as in claim 1 wherein
3. A fire safety system as in claim 1 further comprising
4. A fire safety system as in claim 1 wherein
5. A fire safety system as in claim 4 further comprising
6. A fire safety system as in claim 5 wherein
7. A fire safety system as in claim 6 in combination with a building comprising a plurality of rooms and a common area and further wherein
8. A fire safety system as in claim 7 wherein
9. A fire safety system as in claim 4 in combination with a building comprising a plurality of rooms and further wherein
10. A fire safety system as in claim 9 wherein
11. A fire safety system as in claim 10 wherein
12. A fire safety system as in claim 11 wherein
13. A fire safety system as in claim 12 wherein
14. A fire safety system as in claim 13 wherein
15. A fire safety system as in claim 10 wherein
16. A fire safety system as in claim 15 wherein
17. A fire safety system as in claim 16 wherein
18. A fire safety system as in claim 2 wherein
19. A fire safety system as in claim 2 wherein
20. A fire safety system as in claim 19 wherein
21. A probe for use in a fire safety system, said probe comprising an electrical resistance wire adapted to be juxtapositioned relative to a fusible element which is to be melted to set off a sprinkler head, and
22. A probe as in claim 21 wherein
23. A probe as in claim 22 wherein
24. A probe as in claim 23 wherein
25. A probe as in claim 24 wherein
26. A fire safety system comprising
27. A fire safety system as in claim 25 wherein
28. A fire safety system as in claim 27 wherein
29. A fire safety system as in claim 28 wherein
1. A fire safety system comprising:
2. A fire safety system as in claim 1 wherein
3. A fire safety system as in claim 1 further comprising
4. A fire safety system as in claim 1 wherein
5. A fire safety system as in claim 4 further comprising
6. A fire safety system as in claim 5 wherein
7. A fire safety system as in claim 6 in combination with a building comprising a plurality of rooms and a common area and further wherein
8. A fire safety system as in claim 7 wherein
9. A fire safety system as in claim 4 in combination with a building comprising a plurality of rooms and further wherein
10. A fire safety system as in claim 9 wherein
11. A fire safety system as in claim 10 wherein
12. A fire safety system as in claim 11 wherein
13. A fire safety system as in claim 12 wherein
14. A fire safety system as in claim 13 wherein
15. A fire safety system as in claim 10 wherein
16. A fire safety system as in claim 15 wherein
17. A fire safety system as in claim 16 wherein
18. A fire safety system as in claim 2 wherein
19. A fire safety system as in claim 2 wherein
20. A fire safety system as in claim 19 wherein
21. A probe for use in a fire safety system, said probe comprising an electrical resistance wire adapted to be juxtapositioned relative to a fusible element which is to be melted to set off a sprinkler head, and
22. A probe as in claim 21 wherein
23. A probe as in claim 22 wherein
24. A probe as in claim 23 wherein
25. A probe as in claim 24 wherein
26. A fire safety system comprising
27. A fire safety system as in claim 25 wherein
28. A fire safety system as in claim 27 wherein
29. A fire safety system as in claim 28 wherein
Description:
The present invention relates to improvements in fire safety systems.
Various types of fire safety systems have been developed and employed extensively for many years. One of the most widely used systems involves the provision of sprinkler heads mounted in the ceiling of a room. Such sprinkler heads comprise a fusible link which holds a valve closed under normal conditions. When a fire occurs, the fusible links are melted, allowing the valve to open and water is automatically discharged by the sprinkler heads to extinguish a fire which is presumably located beneath.
Another more recently developed fire safety system, is based on the use of smoke detectors. Such detectors sense an increase in the particulate concentration in the air, as would be caused by smoke from a fire. When a given "smoke level" is reached, an electrical signal is generated by the smoke detector which actuates an alarm system to alert the residents of a building or the like that a fire may be in progress.
While such systems have definite value, they do not provide the necessary level of fire safety which is desirable, if not absolutely necessary, in convalescent homes and other multi-unit residences for persons who may be ill or infirm.
The fusible elements employed with sprinkler heads have a relatively long response time. This is generally satisfactory in protecting a building or its inaminate contents from total distruction. However, it is possible for a heat rise, within such a long response time, to reach the point where a person could be seriously, or even mortally, burned. Different drawbacks are found in conventional smoke detector systems in that they are no more reliable than the ability of a person to react to the alarm they provide. Thus an infirm patient would have little or no ability to protect himself even if he heard the alarm. Even if an attendant were alerted by such an alarm, his ability to react could be seriously affected if a fire rapidly reached a roaring conflagration.
While the need and desirability for improved fire safety is most emphasized by the situation in convalescent homes, there are other circumstances where improvements are also desirable. For example, in private residences, hotels, motels, wharehouses, and the like, it is desirable that a fire safety system give maximum assurance that the entire building or a given area thereof will not reach a stage of conflagration endangering either occupants or contents.
Accordingly, one objective of the present invention is to provide an improved fire safety system for detecting the potential presence of a fire and actuating a sprinkler system before a state of conflagration is reached.
Another object of the invention is to provide an improved fire safety system providing a maximum of protection for patients in convalescent homes or the like.
Another object of the present invention is to attain the above ends in a manner economically compatible with existing fire protection systems.
Another object of the present invention is to provide a unique element for shortening the response time for actuation of sprinkler heads in fulfillment of the above ends.
In the broader aspects of the invention, these ends are attained by the combination of a sprinkler head, a smoke detector, and means responsive to an output signal of the smoke detector for quickly melting the fusible element of the sprinkler head to automatically discharge water therefrom when a given rise in smoke density occurs.
In another aspect of the invention, means are provided for manually actuating means for quickly melting the fusible element of a sprinkler head, thereby discharging water therefrom prior to a fire reaching a stage of conflagration.
These features may be combined and employed in a multi-unit building, such as a convalescent home, with smoke detector and sprinkler head combinations in individual rooms. Means can be also provided, at a central location, such as an attendant's station, to give an indication that one sprinkler head has discharged. This enables remote actuation of all of the remaining sprinkler heads or sprinkler heads in selected rooms by means provided for this purpose. Further, a smoke detector may be provided in a critical location, such as a hallway, to provide an alarm that remote actuation, at the attendant's station of some, or all, of the sprinkler heads may be desirable.
More specifically, the fusible element melting means may take the form of an electrical resistance wire which is juxtapositioned relative to the fusible element, or link, of a conventional sprinkler head. This resistance wire is connected across an electrical potential, preferably of low voltage, which is sufficient to quickly generate a temperature which will melt the fusible element.
The electrical resistance is incorporated, as a separate article of manufacture, in a probe which is incorporated in the electrical circuits actuated either by the smoke detector or the remote actuation means. Preferably, the resistance wire is in the form of a resilient coil which may be compressed between linkage elements of one type of sprinkler head to juxtaposition relative to the fusible element. It is also preferable that the resistance wire be coated with a low melting point dielectric material. This not only insulates the probe from the sprinkler head, but also provides a warning that sprinkler head is about to be discharged as the insulation is burnt off when current is passed therethrough to melt the fusible element. Additionaly, the probe may be provided with means for positively positioning the resistance wire relative to the fusible element. These means may advantageously be formed as extensions of the dielectric material.
The electrical circuit may economically incorporate lights which indicate circuit continuity as well as actuation of a sprinkler head.
The above and other related objects and features of the invention will be apparent from a reading of the following description, with reference to the accompanying drawings, and the novelty thereof pointed out in the appended claims.
IN THE DRAWINGS:
FIG. 1 is a perspective view illustrating the installation of a fire safey system, embodying the present invention, in a convalescent home, or the like;
FIG. 2 is a view of a water sprinkler and associated heating element probe employed in the present invention;
FIG. 3 is a view similar to FIG. 2 illustrating actuation of the water sprinkler;
FIG. 4 is an enlarged view of the heating element probe employed in the present invention;
FIG. 5 is a perspective view of a control box employed herein; and
FIG. 6 is an electrical diagram of the circuit means employed in the present invention.
FIG. 1 is a schematic illustration of a portion of a building, such as a convalescent home, in which the present fire safety system may be incorporated. With more specific reference to a convalescent home, or the like, a two story building is illustrated showing an upper hallway h from which patient rooms may be entered from either side. Specifically rooms r a , r b and r c are illustrated. From the upper hallway h, a stairway s leads to a lower foyer f from which other hallways may extend to other patient's rooms. A receptionist's desk, or nurse's station, st is provided in the foyer f.
Water sprinkler heads 10 and associated heating element probes 12 are mounted on the ceiling of each of the patient rooms r a , r b and r c and are designated by corresponding subscripts. Further, within each of the rooms r a , r b and r c are mounted smoke detectors 14, again identified by corresponding subscripts. Mounted in the hallway h is a further smoke detector 14h.
As will later be described in greater detail, each sprinkler head 10 includes a fusible element which, when melted, releases a valve to permit discharge of water therefrom. Thus, if there should be a fire in any of the rooms, r a , r b or r c which generates sufficient heat to melt the fusible element, water will be discharged from that particular sprinkler into the room. This, is the conventional function of such sprinkler heads which is unaffected by the present invention.
Additionally, each smoke detector in a patient room is electrically connected, by the illustrated wiring, to the resistance probe within the room. When the smoke level in the room reaches a pre-determined level, an electrical signal generated by the smoke detector passes current through the electrical probe and causes the fusible element of the sprinkler to melt and discharge water into the room. Thus, the individual rooms are protected, both from an increase in smoke level, which would indicate a fire, or an incipient fire, as well as from an actual fire which generates, itself, enough heat to melt the fusible element. The above description, as well as that immediately following, is functional only and the actual electric current will later be described in detail.
The smoke detectors 14 are additionally connected, by the illustrated wiring, to control boxes 16 which are identified by corresponding subscripts, at the nurse's station st. Each control box, see FIG. 5, includes a pair of lights 18 and 20, which are preferably of different colors. The lights 18 indicate that the electrical system for the smoke detector is in a ready condition and capable of actuating the associated sprinkler head. The other light, 20, indicates a fire condition wherein the smoke detector has, in fact, actuated the associated electrical probe and sprinkler head. When a light 20 is lit, the nurse or attendant at station st is alerted to the fact that a fire or potential fire exists in a given room. An audible alarm could also be provided in addition to or as an alternative to the warning light 20. Dependant upon the circumstances at the time, the attendant could either check the room involved and/or immediately actuate the electrical probes and discharge water from the sprinklers 10 in adjacent rooms. This latter capability is provided by switches 22 which are provided in each of the control boxes 16. Closing of a switch 22 energizes the associated electrical probe to discharge water from the sprinkler head to which it is connected.
The hallway smoke detector 14h may be employed simply as an alarm device, being connected to a control box 16h at the nurse's station st. The control box 16h, for such purposes would, comprise an alarm light 23 and a switch 25. The alarm light 23 would alert an attendant to either check the area involved or to immediately actuate all of the sprinkler heads 10 in the rooms r a , r b and r c by closing switch 25. Alternatively, the hallway smoke detector 14h could also be connected to a resistance probe which would be associated with a hallway sprinkler and function in a fashion similar to the arrangement in the rooms r a , r b and r c .
The detailed operation and features of the invention will now be described by next referencing FIG. 2. The sprinkler heads 10 may be of existing commercial design. In fact, one of the features of the invention is that it may be used with such existing sprinkler heads without modification thereof and thus may be readily incorporated into a building with an existing sprinkler system.
The sprinkler head 10, in FIG. 2, includes a casting having an upper nipple portion 24 which is threaded into a mounting plate 26. The mounting plate may be secured by screws 28 to a mounting bracket or other structural element forming a part of the room's ceiling c. A short length of tubing 30 connects the nipple 24 to a T fitting 32 in a pressurized Water supply conduit 34. The sprinkler casting also comprises a bridle 34 which extends beneath the nipple outlet, as defined by a valve seat 36. In a state of readiness, discharge of water from the sprinkler head is prevented by a valve member 38 which is held in place by a pair of lever arms 40 and 42 and a fusible link 44. The lever arms 40 and 42 have aligned conical tips 46 and 48 which respectively engage the valve 38 and the bridle 34. A knife edge engagement is provided between the lever arms 40 and 42, at 50, in a slightly offset relationship from the aligned points of engagement of the conical tips 46 and 48. This provides a leverage arrangement requiring only a very small force at the ends of the lever arms to maintain the valve 38 closed against a very substantial water pressure from the water conduit 34. The relatively small closing force may then be provided by the fusible link 44 even though the fusible material is relatively weak. The link 44, see also FIG. 4, comprises two plates, 44a and 44b, having a central offset. These plates may be formed of brass or the like and are joined by the fusible material. The links have a slot and opening in opposite ends, through which the lever arms 40, 42 respectively pass. When a fire occurs, the fusible material melts and the links separate as the lever arms are forced apart and the valve 38 released by the force of the pressurized water. The fusible material is a low melting point eutectic which loses its strength relatively suddenly at a sharply defined temperature. While the response time for release of this link is relatively long, at temperatures close to the melting point of the fusible material, the release time is drastically reduced when the fusible material is subject to a much higher temperature.
The sprinkler head 10 and its fusible link 44 are merely illustrative. Other sprinkler constructions and fusible elements (not necessarily eutectic) therefor can be also employed, at least in the broader aspects of the invention.
Electrical resistance probe 12 is provided to generate a high temperature for melting the fusible link 44 in response to a signal from the associated smoke detector 14 or in response to manual closure of switches 22 or 25 at the control box 16 at the nurse's station st. Each electrical resistance probe 12, referencing also FIG. 4, comprises a coil 52 of nicrome wire or similar electrical resistance material commonly used in heating elements. This coil is disposed between the lever arms 40 and 42 in close proximity to the fusible link 44. The coil 52 functions as a spring to resiliently maintain itself positioned between the arms 40 and 42. The ends of the nicrome wire, forming the coil 52, are connected to insulated electrical leads 53. These connections, as well as the entire length of wire forming the coil 52, are sheathed within a flexible insulating material 54 such as plastisol, silicone rubber or suitable epoxy resin, having a relatively low melting point. The individual loops of the coil are thus insulated from each other and all conductive portions of the probe are insulated from the metal elements of the sprinkler itself. The insulated leads 53 extend to a standard plug-in connector 58. Connector 58 is plugged into a jack 60 from which wires (not shown in FIG. 3) extend in a fashion more explicitly described in the electrical diagram of FIG. 5 and generally as indicated in FIG. 1. The probe 12 is thus a replaceable element. It can be economically replaced in the event it is energized or found defective for some reason.
Another feature to be noted is that insulating material 54 is molded, at the opposite ends of the coil 52, to form gripping lugs 61 which embrace the lever arms 40 and 42. The resilient spring action of the coil 52 holds it in place and the lugs 61 more positively position it relative to the link 44.
When a predetermined electrical potential is connected across the coil 52, heat is quickly generated to melt the fusible element 44, as evidenced by separation of the plates 44a and 44b, and release the arms 40 and 42. When this occurs, the arms 40 and 42 are simply forced from the sprinkler, as water pressure displaces the valve 38 away from the end of the nipple 24 and water automatically is discharged therefrom, being spread over a substantial area by a baffle 62 secured to the bottom of the bridle 34. This condition is illustrated in FIG. 3 wherein it will also be seen that the water being sprayed from the sprinkler 10 splashes against the heated coil 52 to cool it down and provide assurance that the heated coil itself, will not become a fire hazard.
Another feature in the described arrangement is that when energizing current flows through the coil 52, the insulating material 54 is first burned or charred away, causing an unpleasant odor which would alert the person in the room that the sprinkler head was about to discharge. This feature could be employed in various ways. It can serve to alert a person who is mobile to immediately leave the room. It could also be visually ascertained that there is no immediate danger. In the latter event, an inactuation switch (not shown) could be employed to shut down the electrical circuit to the resistance element and prevent unnecessary actuation of the sprinkler, or the same result could be attained by simply pulling the plug 58 from the jack 60.
Referencing next FIG. 6, the electrical circuit employed in the present invention is shown in greater detail. The smoke detectors 14 may be commercially available units, well known to those skilled in the art. Such detectors generate an electrical output signal when a predetermined level of smoke, or particulate concentration is sensed. In the present instance, this output signal is represented by a coil 64 which is energized to displace a contactor 66 and close a switch 67. Each of the switches 67 is connected to one side of a low voltage power supply 68 which may be physically located at the nurse's station st.
The portions of the electrical circuit which include the room smoke detectors 14a, 14b and 14c each comprise a resistance probe 12 and alarm bulb 20 connected in parallel and in series with switches 67, 22 and "ready" bulb 18 which are connected in parallel, all of which is connected across supply 68.
The portion of the electrical circuit which includes the hallway smoke detector 14h comprises the switch 67h connected in series with the area alarm bulb 23, across the power supply 68. Also associated therewith, in the control box 16h is the switch 23 which is a ganged switch connected from one side of the power supply, to provide a separate series connection with each of the resistance probes 12.
With this arrangement, in the illustrated ready condition of the circuit, there is current flow through each of the "ready" bulbs 18, the alarm bulbs 20 and the resistance probes 12. At this point, it will be noted that the resistances of each pair of bulbs 18, 20 is approximately equal and that the resistance of the bulb 18 is substantially greater than that of the probe coil 52. Thus, the greatest voltage drop will be across the bulb 18 and it will be brightly illuminated to indicate the "ready" condition. There will be a much lower drop across the coil 52 and the current flow therethrough will be insufficient to generate enough heat to either burn its insulating material or melt the fusible link. The current flow through bulb 20 will be insufficient to illuminate it. Should there be an open circuit to or through the probe 12, the bulbs 18, 20 would both be illuminated to a reduced brilliance. This would indicate that servicing was required.
When one of the room smoke detectors 14a, b, or c, is actuated, its switch 67 is closed, say switch 67a. This completes a circuit, shorting out the bulb 18a, through the associated probe coil 52a. With the full potential of the power supply 68 connected thereacross, sufficient heat is generated to melt the fusible element in a desired, relatively short time period, say in the order of 15 seconds. At the same time, sufficient current flows through the bulb 20a to illuminate it and give a visual signal at the nurse's station that the sprinkler in room r a is being set off.
At this time, there is an optional capability at the nurse's station st, to either set off all sprinklers or sprinklers in selected rooms. To set off all sprinklers, switch 25 in control box 16h is closed. This connects all of the resistance probes directly across the power supply 68. To set off the sprinkler in a given room, the appropriate switch 22 is closed, connecting the probe for that room directly across the power supply.
While, as pointed out above, the smoke detector for the hallway be similarly connected to actuate a sprinkler head, in the present instance, it is used only as an alarm device. Thus, when switch 67h closes, bulb 25 is illuminated. The attendant at the nurse's station can then make a decision as to what action should be taken and has the same options, as above, to immediately actuate all sprinklers by closing switch 25 or closing switches 24 for individual rooms, as desired.
One other feature of the circuit which provides additional protection is found in the provision of a fuse 70 in series with each of the coils 52. The fuses protect against the possibility of fire resulting from an overload through one of the circuits as a result of a short circuit in a probe 12, particularly when a sprinkler head is discharged.
From the above description, it will be apparent that the present invention, particularly within its broader concepts, provides a great deal of flexibility which will be apparent to those skilled in the art, and which will result in many modifications, particularly for specific applications, which depart from the preferred embodiment herein. For example, and not by way of limitation, a properly constructed fusible element could be incorporated in the electrical circuit and current passed therethrough to melt the element to set off a sprinkler head. Further dispensers for fire suppressants other than water could be employed and in at least some aspects of the invention would be considered equivalent to a water sprinkler head. The spirit and scope of the present invention is therefor to be derived solely from the following claims.
Various types of fire safety systems have been developed and employed extensively for many years. One of the most widely used systems involves the provision of sprinkler heads mounted in the ceiling of a room. Such sprinkler heads comprise a fusible link which holds a valve closed under normal conditions. When a fire occurs, the fusible links are melted, allowing the valve to open and water is automatically discharged by the sprinkler heads to extinguish a fire which is presumably located beneath.
Another more recently developed fire safety system, is based on the use of smoke detectors. Such detectors sense an increase in the particulate concentration in the air, as would be caused by smoke from a fire. When a given "smoke level" is reached, an electrical signal is generated by the smoke detector which actuates an alarm system to alert the residents of a building or the like that a fire may be in progress.
While such systems have definite value, they do not provide the necessary level of fire safety which is desirable, if not absolutely necessary, in convalescent homes and other multi-unit residences for persons who may be ill or infirm.
The fusible elements employed with sprinkler heads have a relatively long response time. This is generally satisfactory in protecting a building or its inaminate contents from total distruction. However, it is possible for a heat rise, within such a long response time, to reach the point where a person could be seriously, or even mortally, burned. Different drawbacks are found in conventional smoke detector systems in that they are no more reliable than the ability of a person to react to the alarm they provide. Thus an infirm patient would have little or no ability to protect himself even if he heard the alarm. Even if an attendant were alerted by such an alarm, his ability to react could be seriously affected if a fire rapidly reached a roaring conflagration.
While the need and desirability for improved fire safety is most emphasized by the situation in convalescent homes, there are other circumstances where improvements are also desirable. For example, in private residences, hotels, motels, wharehouses, and the like, it is desirable that a fire safety system give maximum assurance that the entire building or a given area thereof will not reach a stage of conflagration endangering either occupants or contents.
Accordingly, one objective of the present invention is to provide an improved fire safety system for detecting the potential presence of a fire and actuating a sprinkler system before a state of conflagration is reached.
Another object of the invention is to provide an improved fire safety system providing a maximum of protection for patients in convalescent homes or the like.
Another object of the present invention is to attain the above ends in a manner economically compatible with existing fire protection systems.
Another object of the present invention is to provide a unique element for shortening the response time for actuation of sprinkler heads in fulfillment of the above ends.
In the broader aspects of the invention, these ends are attained by the combination of a sprinkler head, a smoke detector, and means responsive to an output signal of the smoke detector for quickly melting the fusible element of the sprinkler head to automatically discharge water therefrom when a given rise in smoke density occurs.
In another aspect of the invention, means are provided for manually actuating means for quickly melting the fusible element of a sprinkler head, thereby discharging water therefrom prior to a fire reaching a stage of conflagration.
These features may be combined and employed in a multi-unit building, such as a convalescent home, with smoke detector and sprinkler head combinations in individual rooms. Means can be also provided, at a central location, such as an attendant's station, to give an indication that one sprinkler head has discharged. This enables remote actuation of all of the remaining sprinkler heads or sprinkler heads in selected rooms by means provided for this purpose. Further, a smoke detector may be provided in a critical location, such as a hallway, to provide an alarm that remote actuation, at the attendant's station of some, or all, of the sprinkler heads may be desirable.
More specifically, the fusible element melting means may take the form of an electrical resistance wire which is juxtapositioned relative to the fusible element, or link, of a conventional sprinkler head. This resistance wire is connected across an electrical potential, preferably of low voltage, which is sufficient to quickly generate a temperature which will melt the fusible element.
The electrical resistance is incorporated, as a separate article of manufacture, in a probe which is incorporated in the electrical circuits actuated either by the smoke detector or the remote actuation means. Preferably, the resistance wire is in the form of a resilient coil which may be compressed between linkage elements of one type of sprinkler head to juxtaposition relative to the fusible element. It is also preferable that the resistance wire be coated with a low melting point dielectric material. This not only insulates the probe from the sprinkler head, but also provides a warning that sprinkler head is about to be discharged as the insulation is burnt off when current is passed therethrough to melt the fusible element. Additionaly, the probe may be provided with means for positively positioning the resistance wire relative to the fusible element. These means may advantageously be formed as extensions of the dielectric material.
The electrical circuit may economically incorporate lights which indicate circuit continuity as well as actuation of a sprinkler head.
The above and other related objects and features of the invention will be apparent from a reading of the following description, with reference to the accompanying drawings, and the novelty thereof pointed out in the appended claims.
IN THE DRAWINGS:
FIG. 1 is a perspective view illustrating the installation of a fire safey system, embodying the present invention, in a convalescent home, or the like;
FIG. 2 is a view of a water sprinkler and associated heating element probe employed in the present invention;
FIG. 3 is a view similar to FIG. 2 illustrating actuation of the water sprinkler;
FIG. 4 is an enlarged view of the heating element probe employed in the present invention;
FIG. 5 is a perspective view of a control box employed herein; and
FIG. 6 is an electrical diagram of the circuit means employed in the present invention.
FIG. 1 is a schematic illustration of a portion of a building, such as a convalescent home, in which the present fire safety system may be incorporated. With more specific reference to a convalescent home, or the like, a two story building is illustrated showing an upper hallway h from which patient rooms may be entered from either side. Specifically rooms r a , r b and r c are illustrated. From the upper hallway h, a stairway s leads to a lower foyer f from which other hallways may extend to other patient's rooms. A receptionist's desk, or nurse's station, st is provided in the foyer f.
Water sprinkler heads 10 and associated heating element probes 12 are mounted on the ceiling of each of the patient rooms r a , r b and r c and are designated by corresponding subscripts. Further, within each of the rooms r a , r b and r c are mounted smoke detectors 14, again identified by corresponding subscripts. Mounted in the hallway h is a further smoke detector 14h.
As will later be described in greater detail, each sprinkler head 10 includes a fusible element which, when melted, releases a valve to permit discharge of water therefrom. Thus, if there should be a fire in any of the rooms, r a , r b or r c which generates sufficient heat to melt the fusible element, water will be discharged from that particular sprinkler into the room. This, is the conventional function of such sprinkler heads which is unaffected by the present invention.
Additionally, each smoke detector in a patient room is electrically connected, by the illustrated wiring, to the resistance probe within the room. When the smoke level in the room reaches a pre-determined level, an electrical signal generated by the smoke detector passes current through the electrical probe and causes the fusible element of the sprinkler to melt and discharge water into the room. Thus, the individual rooms are protected, both from an increase in smoke level, which would indicate a fire, or an incipient fire, as well as from an actual fire which generates, itself, enough heat to melt the fusible element. The above description, as well as that immediately following, is functional only and the actual electric current will later be described in detail.
The smoke detectors 14 are additionally connected, by the illustrated wiring, to control boxes 16 which are identified by corresponding subscripts, at the nurse's station st. Each control box, see FIG. 5, includes a pair of lights 18 and 20, which are preferably of different colors. The lights 18 indicate that the electrical system for the smoke detector is in a ready condition and capable of actuating the associated sprinkler head. The other light, 20, indicates a fire condition wherein the smoke detector has, in fact, actuated the associated electrical probe and sprinkler head. When a light 20 is lit, the nurse or attendant at station st is alerted to the fact that a fire or potential fire exists in a given room. An audible alarm could also be provided in addition to or as an alternative to the warning light 20. Dependant upon the circumstances at the time, the attendant could either check the room involved and/or immediately actuate the electrical probes and discharge water from the sprinklers 10 in adjacent rooms. This latter capability is provided by switches 22 which are provided in each of the control boxes 16. Closing of a switch 22 energizes the associated electrical probe to discharge water from the sprinkler head to which it is connected.
The hallway smoke detector 14h may be employed simply as an alarm device, being connected to a control box 16h at the nurse's station st. The control box 16h, for such purposes would, comprise an alarm light 23 and a switch 25. The alarm light 23 would alert an attendant to either check the area involved or to immediately actuate all of the sprinkler heads 10 in the rooms r a , r b and r c by closing switch 25. Alternatively, the hallway smoke detector 14h could also be connected to a resistance probe which would be associated with a hallway sprinkler and function in a fashion similar to the arrangement in the rooms r a , r b and r c .
The detailed operation and features of the invention will now be described by next referencing FIG. 2. The sprinkler heads 10 may be of existing commercial design. In fact, one of the features of the invention is that it may be used with such existing sprinkler heads without modification thereof and thus may be readily incorporated into a building with an existing sprinkler system.
The sprinkler head 10, in FIG. 2, includes a casting having an upper nipple portion 24 which is threaded into a mounting plate 26. The mounting plate may be secured by screws 28 to a mounting bracket or other structural element forming a part of the room's ceiling c. A short length of tubing 30 connects the nipple 24 to a T fitting 32 in a pressurized Water supply conduit 34. The sprinkler casting also comprises a bridle 34 which extends beneath the nipple outlet, as defined by a valve seat 36. In a state of readiness, discharge of water from the sprinkler head is prevented by a valve member 38 which is held in place by a pair of lever arms 40 and 42 and a fusible link 44. The lever arms 40 and 42 have aligned conical tips 46 and 48 which respectively engage the valve 38 and the bridle 34. A knife edge engagement is provided between the lever arms 40 and 42, at 50, in a slightly offset relationship from the aligned points of engagement of the conical tips 46 and 48. This provides a leverage arrangement requiring only a very small force at the ends of the lever arms to maintain the valve 38 closed against a very substantial water pressure from the water conduit 34. The relatively small closing force may then be provided by the fusible link 44 even though the fusible material is relatively weak. The link 44, see also FIG. 4, comprises two plates, 44a and 44b, having a central offset. These plates may be formed of brass or the like and are joined by the fusible material. The links have a slot and opening in opposite ends, through which the lever arms 40, 42 respectively pass. When a fire occurs, the fusible material melts and the links separate as the lever arms are forced apart and the valve 38 released by the force of the pressurized water. The fusible material is a low melting point eutectic which loses its strength relatively suddenly at a sharply defined temperature. While the response time for release of this link is relatively long, at temperatures close to the melting point of the fusible material, the release time is drastically reduced when the fusible material is subject to a much higher temperature.
The sprinkler head 10 and its fusible link 44 are merely illustrative. Other sprinkler constructions and fusible elements (not necessarily eutectic) therefor can be also employed, at least in the broader aspects of the invention.
Electrical resistance probe 12 is provided to generate a high temperature for melting the fusible link 44 in response to a signal from the associated smoke detector 14 or in response to manual closure of switches 22 or 25 at the control box 16 at the nurse's station st. Each electrical resistance probe 12, referencing also FIG. 4, comprises a coil 52 of nicrome wire or similar electrical resistance material commonly used in heating elements. This coil is disposed between the lever arms 40 and 42 in close proximity to the fusible link 44. The coil 52 functions as a spring to resiliently maintain itself positioned between the arms 40 and 42. The ends of the nicrome wire, forming the coil 52, are connected to insulated electrical leads 53. These connections, as well as the entire length of wire forming the coil 52, are sheathed within a flexible insulating material 54 such as plastisol, silicone rubber or suitable epoxy resin, having a relatively low melting point. The individual loops of the coil are thus insulated from each other and all conductive portions of the probe are insulated from the metal elements of the sprinkler itself. The insulated leads 53 extend to a standard plug-in connector 58. Connector 58 is plugged into a jack 60 from which wires (not shown in FIG. 3) extend in a fashion more explicitly described in the electrical diagram of FIG. 5 and generally as indicated in FIG. 1. The probe 12 is thus a replaceable element. It can be economically replaced in the event it is energized or found defective for some reason.
Another feature to be noted is that insulating material 54 is molded, at the opposite ends of the coil 52, to form gripping lugs 61 which embrace the lever arms 40 and 42. The resilient spring action of the coil 52 holds it in place and the lugs 61 more positively position it relative to the link 44.
When a predetermined electrical potential is connected across the coil 52, heat is quickly generated to melt the fusible element 44, as evidenced by separation of the plates 44a and 44b, and release the arms 40 and 42. When this occurs, the arms 40 and 42 are simply forced from the sprinkler, as water pressure displaces the valve 38 away from the end of the nipple 24 and water automatically is discharged therefrom, being spread over a substantial area by a baffle 62 secured to the bottom of the bridle 34. This condition is illustrated in FIG. 3 wherein it will also be seen that the water being sprayed from the sprinkler 10 splashes against the heated coil 52 to cool it down and provide assurance that the heated coil itself, will not become a fire hazard.
Another feature in the described arrangement is that when energizing current flows through the coil 52, the insulating material 54 is first burned or charred away, causing an unpleasant odor which would alert the person in the room that the sprinkler head was about to discharge. This feature could be employed in various ways. It can serve to alert a person who is mobile to immediately leave the room. It could also be visually ascertained that there is no immediate danger. In the latter event, an inactuation switch (not shown) could be employed to shut down the electrical circuit to the resistance element and prevent unnecessary actuation of the sprinkler, or the same result could be attained by simply pulling the plug 58 from the jack 60.
Referencing next FIG. 6, the electrical circuit employed in the present invention is shown in greater detail. The smoke detectors 14 may be commercially available units, well known to those skilled in the art. Such detectors generate an electrical output signal when a predetermined level of smoke, or particulate concentration is sensed. In the present instance, this output signal is represented by a coil 64 which is energized to displace a contactor 66 and close a switch 67. Each of the switches 67 is connected to one side of a low voltage power supply 68 which may be physically located at the nurse's station st.
The portions of the electrical circuit which include the room smoke detectors 14a, 14b and 14c each comprise a resistance probe 12 and alarm bulb 20 connected in parallel and in series with switches 67, 22 and "ready" bulb 18 which are connected in parallel, all of which is connected across supply 68.
The portion of the electrical circuit which includes the hallway smoke detector 14h comprises the switch 67h connected in series with the area alarm bulb 23, across the power supply 68. Also associated therewith, in the control box 16h is the switch 23 which is a ganged switch connected from one side of the power supply, to provide a separate series connection with each of the resistance probes 12.
With this arrangement, in the illustrated ready condition of the circuit, there is current flow through each of the "ready" bulbs 18, the alarm bulbs 20 and the resistance probes 12. At this point, it will be noted that the resistances of each pair of bulbs 18, 20 is approximately equal and that the resistance of the bulb 18 is substantially greater than that of the probe coil 52. Thus, the greatest voltage drop will be across the bulb 18 and it will be brightly illuminated to indicate the "ready" condition. There will be a much lower drop across the coil 52 and the current flow therethrough will be insufficient to generate enough heat to either burn its insulating material or melt the fusible link. The current flow through bulb 20 will be insufficient to illuminate it. Should there be an open circuit to or through the probe 12, the bulbs 18, 20 would both be illuminated to a reduced brilliance. This would indicate that servicing was required.
When one of the room smoke detectors 14a, b, or c, is actuated, its switch 67 is closed, say switch 67a. This completes a circuit, shorting out the bulb 18a, through the associated probe coil 52a. With the full potential of the power supply 68 connected thereacross, sufficient heat is generated to melt the fusible element in a desired, relatively short time period, say in the order of 15 seconds. At the same time, sufficient current flows through the bulb 20a to illuminate it and give a visual signal at the nurse's station that the sprinkler in room r a is being set off.
At this time, there is an optional capability at the nurse's station st, to either set off all sprinklers or sprinklers in selected rooms. To set off all sprinklers, switch 25 in control box 16h is closed. This connects all of the resistance probes directly across the power supply 68. To set off the sprinkler in a given room, the appropriate switch 22 is closed, connecting the probe for that room directly across the power supply.
While, as pointed out above, the smoke detector for the hallway be similarly connected to actuate a sprinkler head, in the present instance, it is used only as an alarm device. Thus, when switch 67h closes, bulb 25 is illuminated. The attendant at the nurse's station can then make a decision as to what action should be taken and has the same options, as above, to immediately actuate all sprinklers by closing switch 25 or closing switches 24 for individual rooms, as desired.
One other feature of the circuit which provides additional protection is found in the provision of a fuse 70 in series with each of the coils 52. The fuses protect against the possibility of fire resulting from an overload through one of the circuits as a result of a short circuit in a probe 12, particularly when a sprinkler head is discharged.
From the above description, it will be apparent that the present invention, particularly within its broader concepts, provides a great deal of flexibility which will be apparent to those skilled in the art, and which will result in many modifications, particularly for specific applications, which depart from the preferred embodiment herein. For example, and not by way of limitation, a properly constructed fusible element could be incorporated in the electrical circuit and current passed therethrough to melt the element to set off a sprinkler head. Further dispensers for fire suppressants other than water could be employed and in at least some aspects of the invention would be considered equivalent to a water sprinkler head. The spirit and scope of the present invention is therefor to be derived solely from the following claims.