US3835931A

US3835931A - Discharge head and fire protection system utilizing same whereby the head is actuatable in response to two separate temperatures

Info

Publication number: US3835931A
Application number: US00412417A
Authority: US
Inventors: W Livingston
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-05-25
Filing date: 1973-11-02
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17

Abstract

A discharge head for use in a fire protection system wherein the head is normally closed and a fire responsive device is adapted to open same in response to a first predetermined fire condition. A second fire responsive device opens the head in response to a second predetermined fire condition and a control selectively controls the operation of the first and second fire responsive devices.

Description

tlnited States Patent 1 1 Livingston 1 Sept. 17, 1974 DISCHARGE HEAD AND FIRE PROTECTION SYSTEM UTILIZING SAME WHEREBY THE HEAD IS ACTUATABLE IN RESPONSE TO TWO SEPARATE TEMPERATURES [76] Inventor: William L. Livingston, 283

Norwood St., Sharon, Mass. 02067 [22] Filed: Nov. 2, 1973 [21] Appl. No.2 412,417

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 256,820, May 25, 1972, abandoned, which is a continuation of Scr. No. 160,715, July 8, 1971, abandoned.

[52] U.S. Cl 169/70, 169/16, 169/37 [51] Int. Cl. A62c 37/08 [58] Field of Search 169/5, 16, 1 B, 37, 41,

[56] References Cited UNITED STATES PATENTS Livingston 169/37 X Livingston 169/16 X Mears at all. 169/37 Primary ExaminerM. Henson Wood, Jr. Assistant Examiner-Michael Y. Mar

Attorney, Agent, or Firm-Lane, Aitken, Dunner & Ziems [57] ABSTRACT A discharge head for use in a tire protection system wherein the head is normally closed and a fire responsive device is adapted to open same in response to a first predetermined fire condition. A second fire responsive device opens the head in response to a second predetermined fire condition and a control selectively controls the operation of the first and second fire responsive devices.

39 Claims, 4 Drawing Figures PAIENIED SEPI mm SHEU 2 OF 2 DISCHARGE HEAD AND FIRE PROTECTION SYSTEM UTILIZING SAME WHEREBY THE HEAD IS ACTUATABLE IN RESPONSE TO TWO SEPARATE TEMPERATURES CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation in part of application Ser. No. 256,820 filed May 25, 1972 now abandoned, by William L. Livingston which in turn is a continuation of application Ser. No. 160,715, filed July 8, 1971 now abandoned, by William L. Livingston, both of said applications being assigned to the same assignee as the present invention.

BACKGROUND OF THE INVENTION This invention relates to a discharge head and a fire protection system incorporating a plurality of such heads, in which the heads are adapted to open in response to two separate fire conditions occurring in the space to be protected.

In US. patent application Ser. No. 72,333, filed on Sept. 15, 1970 now US. Pat. No. 3,653,444, by the inventor of the present invention, and assigned to the same assignee as the present invention, a fire protection system is disclosed in which a plurality of discharge heads are adapted to be thermally actuated in response to a predetermined temperature to render them conditionable for opening and discharging extinguishant. The number of such heads that are opened are limited by means of a pressure floor in which a predetermined pressure at each individual head must be exceeded before the head will open.

Although this type system proved to be extremely effective in fighting high challenge fires, it has since been discovered that two mutually exclusive factors considerably influence the performance of the system. On one hand, it was found to be extremely desirable to actuate the heads at a relatively low temperature such as approximately 150200 to insure that heads located immediately above the fire would open in a relatively quick manner after initiation of a fire and begin to discharge extinguishant towards the fire to fight it at its early stages.

However, it was also discovered that this relatively low actuation temperature often caused several of the heads to be actuated prematurely due to the fact that their temperature responsive mechanisms were more susceptible to external factors, such as air currents, ambient temperatures, and the convective circulation of gaseous products of combustion, etc. As a result, the heads would often be prevented from opening in a logical sequence, i.e., in direct proportion to their distance from the location of the fire. This plus the fact that the above-mentioned pressure floor would limit the number of heads that opened also often resulted in heads being opened which were located a greater distance from the fire than heads that were prevented from opening. Since the heads are in the form of direct discharge nozzles which operate to discharge a relatively high volume of extinguishant, these deficiencies could be disastrous, since it is essential to the effective operation of such a system that the heads located immediately above the fire be the ones that are actually opened initially to fight the fire.

A way of overcoming this illogical operation would be to raise the response temperature of the individual heads, such as to a value of approximately 350-450. In this manner, the above-mentioned external influences prevailing in the building would have less effect upon the heads, and the heads located the closest to the fire would open in a logical sequence. However, the existence of this relatively high response temperature causes the system to respond slowly to the existence of a fire, often to an extent that would permit the tire to reach proportions that rendered it impossible to extinguish.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a discharge head, and a fire protection system employing a plurality of such heads, in which the head is adapted to be opened in response to at least two temperatures, along with means to selectively control the actuation temperature.

It is a further object of the present invention to provide a head and system of the above type in which the heads are adapted to open regardless of the prevailing conditions upon a predetermined relatively high temperature being attained.

Toward the fulfillment of these and other objects the discharge head of the present invention comprises a body member having an inlet for connecting to a source of fluid and an outlet, means normally preventing the discharge of fluid from said outlet, first fire responsive means adapted to permit the discharge of fluid from said outlet in response to a first predetermined fire condition, second fire responsive means adapted to permit the discharge of fluid from said outlet in response to a second predetermined fire condition, and control means for selectively controlling the operation of said first and second fire responsive means.

BRIEF DESCRIPTION OF THE DRAWINGS jects of the present invention. The drawings illustrate the best mode presently contemplated for carrying out the objects of the invention and are not to be construed as restrictions or limitations on its scope. In the drawings:

FIG. 1 is a vertical sectional view of a direct discharge head employed in the system of FIGS. 1 and 2;

FIGS. 2 and 3 are enlarged partial views of the head of FIG. 1; and

FIG. 4 is a schematic, perspective view of a building having a fire protection system embodying features of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, the discharge head of the present invention is in the form of a direct discharge nozzle shown in general by the reference numeral 10 and comprising a cylindrical body member 12 having an upper end portion which is internally threaded as shown at 14 for connection to a source of extinguishant such as water, and a lower end portion which defines an outlet orifice 16 of a reduced cross-section. A pair of

spiral vanes

18a and 18b are fixed within the body member 12 for imparting a swirling motion to an extinguishant, such as water, flowing downwardly therethrough in a conventional manner. The

vanes

18a and 18b support a hollow central hub 20 which, in turn, slidably supports a rod 22 having a head assembly 24 fixed on its lower end. The head assembly 24 operates to block the outlet orifice l6, and will be described in detail later.

The rod 22 is latched in the position shown in FIG. 1 by a latching assembly shown in general by the reference numeral 30 in FIG. 1. This assembly includes a rod 32 which slidably extends through an externally threaded boss 34 projecting from the side of the body member 12. One end of the rod 32 extends through the vane 18a and the wall of the hub 20 into a slot 36 in the rod 22 to latch it in the position shown in FIG. 1.

A sleeve 38 is threaded on the end of the boss 34. The outer end of the sleeve 38 is closed off by an externally threaded stub shaft 40 having a yoke 42 thereon. The rod 32 slidably extends through the stub shaft 40, and the other end of the rod engages a conventional fusible link assembly 44 positioned within the yoke 42. The assembly 44 prevents movement of the rod 32 to the right as viewed in FIG. 1, until the heat of a fire fuses a portion of the assembly so that it collapses. Since the yoke 42 and the fuse assembly 44 are the standard types commonly used in conventional sprinkler heads, they will not be described in greater detail.

The rod 32 has a piston head 46 mounted thereon which slidably engages the internal wall of the sleeve 38. A spring 48 is positioned between the boss 34 and the piston head 46 to bias the piston head and the rod 32 to the right with a predetermined biasing force.

With this arrangement, the piston head 46 and the rod 32 will be driven to the right under the action of the spring 48 upon the fusible link assembly 44 collapsing in response to the head of the fire, which results in an unlatching of the rod 22.

The head assembly 24 is shown in detail in FIG. 2, and includes a tubular member 50 the outer peripheral surface of which is spaced a small distance from the inner wall of the body 12. A pair of

sealing rings

52 and 54 are disposed in annular grooves formed in the peripheral surface of the tubular member 50 and engage the inner wall of the body member 12. The rod 22 extends through the central bore of the tubular member 50, and and O-ring 56 is disposed in an annular groove formed in the inner wall of the tubular member and engages the outer surface of the rod.

A sleeve 58 extends between the outer surface of the rod 22 and the inner wall of the tubular member 50 and flush with the bottom ends thereof, as viewed in FIG. 2. The sleeve 58 is formed of a fusible material which, in its non-fused condition, connects the tubular member 50 to the rod 22, and which is adapted to fuse at a predetermined temperature and break the connection, as will be described in detail later.

As shown in FIGS. 1 and 3, an externally threaded boss 60 projects from a side of the body member 12 opposite the side of the boss 34. A sleeve 62 is threaded on the end of the boss 60 and is closed off by a stub shaft 64, with a chamber 66 being defined by the

stub shafts

60 and 64 and the sleeve 62. A piston head 68 is disposed in the chamber 66 and sealingly engages the inner walls of the sleeve 62 by means of an O-ring seal 70.

A yoke 72 is formed on the stub shaft 64 and supports a fusible link assembly 74, identical in design and function to the link assembly 44. The chamber 66 communicates with the interior of the body member 12 by means of a passage 76 formed through the stub shaft 60, and with the interior of the yoke 72 by means of a passage 78 formed through the stub shaft 64. A closure member, in the form of a disc 80, is positioned within the yoke 72 and is retained in a position closing the end of the passage 78 by menas of the link assembly 74.

A circular flange 82 extends from a surface 68a of the piston head 68 and receives an end portion of a spring 84 extending between the latter surface and the end of the stub shaft 60. The flange 82 and the spring 84 align the piston head 68 in the chamber 66 and urge the piston head in a direction from right to left as viewed in FIG. 1, away from the end of the passage 76. An opening 86 is provided through the piston head 68 to provide for water leakage through the piston head so that when the head 10 is in its quiescent state shown in FIG. 1 and is connected to a source of pressurized water, the water in the body member 12 will pass through the passage 76 into one end of the chamber 66, and through the leak passage 86 into the chamber on the other side of the piston head 68. Since the closure member seals off the passage 78, the water pressure across the piston head 68 will be equalized. The force of the spring 84 is selected so that the piston head 68 is normally spaced from the corresponding ends of the

passages

76 and 78. A nylon thread 90 has one end fastened to the surface 68a of the piston head 68, and the other end fastened to the end of the rod 22, for reasons that will be explained in detail later.

According to an exemplary embodiment of the present invention, the fusible link assembly 44 will be selected to collapse at a predetermined relatively low temperature such as 286F., the fusible link assembly 74 will be selected to collapse at an intermediate temperature such as 500F., and the fusible sleeve 58 will be selected to fuse at a relatively high temperature, such as 900F. Also, the diameter and material of the thread 90 can be selected so that it severs in response to a predetermined tension acting thereon which, according to the exemplary embodiment, would be reached when the pressure in the body member 12 reaches approximately 30 psi.

As shown in FIG. 4, a plurality of heads 10 are installed as part of a fixed fire protection system in a building shown in general by the reference numeral 100. The system comprises a buried feed main 104 connected to a municipal water supply line 106 for delivering the water to a riser 108. The riser 108 is connected to a cross-main which, in turn, is connected to a plurality of branch lines 122 via couplings 124. It is understood that the cross-main 120 and the branch lines 122 are suspended near the ceiling of the building in a conventional manner.

A plurality of heads 10 are attached to each branch line 122 by means of nipples or the like (not shown in detail). The buried feed main 104 extends beyond the riser 108 and can be connected to risers of other buildings or, in the case of a large building, to other risers in the same building.

The heads 10 are equally spaced apart, with the heads on each branch line 122 being staggered relative to the heads on its adjacent branch lines. The water is supplied to the nozzles at a pressure of approximately 40-50 psi by the water main 106.

In the event the thermal link assembly 44 of a particular head 10 collapses in response to a temperature of approximately 286F. in its immediate vicinity, its piston head 46 and the rod 32 will be driven to the right as viewed in FIG. 1 under the action of the spring 48. This unlatches the rod 22 and frees it, along with the head assembly 24. Since the piston head 68 is held in the chamber 66 due to the absence of a pressure differential thereacross, a tension is applied to the thread 90 directly proportional to the water pressure in the body member 12 acting on the upper surface of the head assembly 24.

In the event the pressure within the body member 12 exceeds the above-mentioned 30 psi, the thread 90 will break and the head assembly 24, along with the rod 22, will be expelled from the body member under the pressure of the water. This will permit a discharge of the water from the outlet orifice 16 in a conical discharge pattern due to the swirling motion applied to the water by the

vanes

18a and 18b. If the pressure in the body member 12 does not exceed 30 psi, the rod 22 and the plug member 24 will be retained in the position shown in FIG. 1 despite the collapse of the link assembly 44 and the unlatching movement of the rod 32.

In the event the thermal link assembly 74 later collapses due to the temperature in its immediate vicinity exceeding its response temperature of approximately 500F., the closure member 80 will be freed from the end of the passage 78 and the water pressure in the left side of the chamber 66 will be relieved, resulting in a movement of the piston head 68 from right to left as viewed in FIG. 1 under the action of rhe water pressure acting on its surface 68A. This applies an additional tension to the thread 90, since it is now being pulled apart at both ends by virtue of the pressure acting on the upper surface of the head assembly 24 and on the surface 68a of the piston head 68. Assuming the area of the surface 68a of the piston head 68 is twice that of the area of the upper surface of the head assembly 24, the tension applied to the thread 90 will be doubled and the pressure required to break the thread thus will be reduced by one-half, or to psi. Therefore, in the event the pressure in the body member 12 exceeds 15 psi after collapse of the link assembly 74, the "head assembly 24 and the rod 22 will be expelled, and the water will be discharged from the outlet orifice 16.

In the event the fusing of the link assembly 74 does not result in an expulsion of the plug member 24 and the rod 22 from the body member 12 due to the pressure existing in the interior of the body member 12 being below 15 psi, the head 10 will not be opened unless the head of the fire rises to the fusible temperature of the sleeve 58, which according to the exemplary embodiment is 900F. In the latter case, the sleeve 58 will melt and permit a release of the tubular member 50 from the rod 22 and a resultant discharge of the member 50 from the outlet orifice 16, with the only pressure requirement in the body member 12 at this stage being enough pressure to force the member 50 out from the orifice.

Of course, it can be appreciated that if the latching mechanism 30, the piston 68, or any other of the above components, become jammed, the fusible sleeve 58 will permit a failsafe mode of operation in the event the temperature reaches its fusing temperature of 900F.

Of course, the other heads 10 making up the complete system will operate in the same manner as dc scribed above, with the system therefore operating in a manner to provide several advantages. First of all, the

number of heads that are initially opened in response to the relatively high pressure floor will be limited, which insures that their water will be supplied at a relatively high pressure. Since these opened nozzles will undoubtedly be located directly over the fire, and since they will not be robbed of water or water pressure by any remote heads, their fire fighting capability will be significant.

Also, in the event the first set of heads to be actuated are ineffective in fighting the fire, additional heads may later be opened in the event the intermediate fusion temperature and the relatively low pressure floor are reached. This increases the flexibility of the system to a point where an optimum discharge of extinguishant is obtained despite differences in the severity of the fires.

Of course, in the event that the opened heads have completely failed in curtailing the advance of the fire, or that one or more of the heads have been rendered inoperative due to jamming, or the like, additional heads can be actuated if the temperature in their vicinity exceeds the temperature required to melt the sleeve 58, as discussed above.

It is also understood that several variations may be made in the foregoing without departing from the scope of the invention. For example, the relative areas of the surface 68a of the piston head 68 and the upper surface of the head assembly 24 may be varied in order to vary the amount of pressure required to break the nylon thread and therefore actuate the nozzles in response to the relatively low pressure floor. Also, the above temperatures and pressures can be varied in accordance with particular design requirements. For example, the fusible link assembly 44 can be designed to collapse at the fusible link assembly 77 can be designed to collapse at 350 and the fusible sleeve can be designed to fuse at 500.

Of course, other variations of the specific construction and arrangement of the discharge head and system disclosed above can be made by those skilled in the art without departing from the invention as defined in the appended claims.

I claim:

1. A discharge head for use in a fire protection system comprising a body member having an inlet for connecting to a source of extinguishant and an outlet, means normally preventing the discharge of extinguishant from said outlet, first fire responsive means adapted to permit the discharge of extinguishant from said outlet in response to a first predetermined fire condition, second fire responsive means adapted to permit the discharge of extinguishant from said outlet in response to a second predetermined fire condition, and control means for selectively controlling the operation of said first and second fire responsive means.

2. The head of claim 1 wherein said first predetermined fire condition is the existence of a first predetermined temperature in the space to be protected from fire and said second predetermined fire condition is the existence of a second predetermined temperature in said space of a greater value than said first predetermined temperature.

3. The head of claim 1 wherein said control means selectively controls the operation of said first and second fire responsive means in response to a predetermined conditon of said system.

4. The head of claim 1 wherein said control means selectively controls the operation of said first and second fire responsive means in response to a predetermined extinguishant pressure existing in said head.

5. The head of claim 4 wherein said control means is adapted to permit the operation of said first fire responsive means in response to the extinguishant pressure in said head exceeding a first predetermined value.

6. The head of claim 5 wherein said control means is adapted to defeat the operation of said first fire responsive means and permit the operation of said second fire responsive means in response to the extinguishant pressure in said head being lower than said first predetermined value and greater than a second predetermined value lower than said first predetermined value.

7. The head of claim 6 wherein said control means prevents the discharge of extinguishant from said outlet in the event the extinguishant pressure in said head is below said second predetermined fire conditions.

8. The head of claim 7 further comprising third fire responsive means responsive to a third predetermined fire condition for permitting the discharge of extinguishant from said outlet despite the extinguishant pressure in said head being below said first and second predetermined values.

9. The head of claim 8 wherein said first, second and third predetermined fire conditions are in the form of first, second and third predetermined temperatures, respectively, occurring in the space to be protected from fire, said second predetermined temperature being greater than said first predetermined temperature and said third predetermined temperature being greater than said second predetermined temperature.

10. A fire protection system comprising a plurality of discharge heads mounted in an elevated position relative to the space to be protected from fire, means for connecting said heads to a source of pressurized extinguishant, means normally preventing the discharge of extinguishant from said heads, first fire responsive means adapted to selectively open said heads to permit the discharge of extinguishant therefrom in response to a first predetermined fire condition, second fire responsive means adapted to selectively open said heads to permit the discharge of extinguishant therefrom in response to a second predetermined fire condition, and control means for selectively controlling the operation of said first and second fire responsive means.

11. The system of claim 10 wherein said first predetermined fire condition is the existence of a first predetermined temperature in said space and said second predetermined fire condition is the existence of a second predetermined temperature in said space of a greater value than said first predetermined temperature.

12. The system of claim 10 wherein said control means selectively controls the operation of said first and second fire responsive means in response to a predetermined condition of said system.

13. The system of claim 10 wherein said control means selectively controls the operation of said first and second fire responsive means in response to a predetermined extinguishant pressures existing in said heads.

14. The system of claim 10 wherein said first and second fire responsive means comprises a first and second fire responsive devices associated with each of said heads.

15. The system of claim 14 wherein said control means is adapted to permit the operation of first fire responsive device associated with a particular head in response to the extinguishant pressure in said head exceeding a first predetermined value.

16. The system of claim 15 wherein said control means is adapted to defeat the operation of said first fire responsive device and permit the operation of its corresponding second fire responsive device in response to the extinguishant pressure in said head being lower than said first predetermined value and greater than a second predetermined value lower than said first predetermined value.

17. The system of claim 16 wherein said control means prevents the discharge of extinguishant from said head in the event the extinguishant pressure in said head is below said second predetermined value despite the existence of said first or second predetermined fire conditions.

18. The system of claim 17 further comprising third fire responsive means associated with each head and responsive to a third predetermined fire condition for permitting the discharge of extinguishant from said head despite the extinguishant pressure in said head being below said first and second predetermined values.

19. The system of claim 18 wherein said first, second and third predetermined fire conditions are in the form of first, second and third predetermined temperatures, respectively, occurring in the space to be protected from fire, said second predetermined temperature being greater than said first predetermined temperatures and said third predetermined temperature being greater than said second predetermined temperature.

20. A discharge head for use in a fire protection system, said head comprising a closure member normally closing said head to prevent the discharge of extinguishant from said head, first means for opening said head in response to the existence of both a first predetennined fire condition in the space to be protected and a first predetermined condition of said system, and second means for opening said head in response to the existence of both a second predetermined fire condition in said space and a second predetermined condition of said system in the event said head is not opened by said first means.

21. The head of claim 20 further comprising third means responsive to a third predetermined fire condition for opening said head in the event said head is not opened by said first means and said second means.

22. The head of claim 20 wherein said first predetermined fire condition is a first predetermined temperature in said space and wherein said second predetermined fire condition is a second predetermined temperature in said space higher than said first predetermined temperature.

23. The head of claim 22 further comprising third means responsive to a third predetermined temperature in said space for opening said head in the event said head is not opened by said first means and said second means, said third predetermined temperature being higher than said second predetermined temperature.

24. The head of claim 20 wherein said first predetermined condition of said system is a first predetermined extinguishant pressure in said system, and wherein said second predetermined condition of said system is a second predetermined extinguishant pressure in said system less than said first predetermined extinguishant pressure.

25. The head of claim 24 wherein said first and second predetermined extinguishant pressures are the pressures of the extinguishant in said head.

26. The head of claim 20 wherein said first means comprises means for retaining said closure member in an extinguishant discharge preventing position in said head, said retaining means being responsive to said first predetermined fire condition.

27. The head of claim 26 wherein said first predetermined condition of said system is a predetermined extinguishant pressure and wherein said first means further comprises connection means for connecting said plug means in said extinguishant discharge preventing position in said head, said connection means being adapted to release said closure member in response to a predetermined tension being placed thereon as a result of said predetermined extinguishant pressure.

28. The head of claim 27 wherein said second means comprises means to vary said tension in response to said second predetermined fire condition.

29. The head of claim 28 wherein said first predetermined fire condition is a first predetermined temperature in said space and wherein said second predetermined fire condition is a second predetermined temperature in said space higher than said first predetermined temperature.

30. A fire protection system comprising a plurality of discharge heads mounted in an elevated position relative to the space to be protected from fire, means for connecting said heads being normally closed and being adapted to open to discharge extinguishant, first means for selectively opening said heads in response to the existence of both a first predetermined fire condition in said space and a first predetermined condition of said system, and second means for selectively opening said heads in response to the existence of both a second predetermined fire condition in said space and a second predetermined condition of said system in the event said heads are not opened by said first means.

31. The system of claim 30 further comprising third means responsive to a third predetermined fire condition for opening said heads in the event said heads are not opened by said first means and said second means.

32. The system of claim 31 wherein said first predetermined fire condition is a first predetermined temperature in said space and wherein said second predetermined fire condition is a second predetermined temperature in said space higher than said first predetermined temperature.

33. The system of claim 32 further comprising third means responsive to a third predetermined temperature in said space for opening said heads in the event said heads are not opened by said first means and said second means; said third predetermined temperature being higher than said second predetermined tempera ture.

34. The system of claim 30 wherein said first predetermined condition of said system is a first predetermined extinguishant pressure in said system, and wherein said second predetermined condition of said system is a second predetermined extinguishant pressure in said system less than said first predetermined extinguishant pressure.

35. The system of claim 34 wherein said first and second predetermined extinguishant pressures are the pressures of the extinguishant in said heads.

36. The system of claim 30 wherein each of said heads comprises a body member, and plug means in said body member for preventing the discharge of said extinguishant therefrom, and wherein said first means comprises means for retaining said plug means in an extinguishant discharge preventing position in said body member, said retaining means being responsive to said first predetermined fire condition for releasing said plug means.

37. The system of claim 36 wherein said first predetermined condition of said system is a predetermined extinguishant pressure in each of said heads, and wherein said first means further comprises connection means for connecting said plug means in an extinguishant discharge preventing position in said body member, said connection means being adapted to release said plug means in response to a predetermined tension being placed thereon as a result of said predetermined extinguishant pressure.

38. The system of claim 37 wherein said second means comprises means to vary said tension in response to said second predetermined fire condition.

39. The system of claim 38 wherein said first predetermined fire condition is a first predetermined temperature in said space and wherein said second predetermined fire condition is a second predetermined temperature in said space higher than said first predetermined temperature.

3,835,931 Dated September 17, 1974 WILLIAM L. LIVINGSTON Patent No.

Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, linel9, a fter "predetermined" add -value despite the existence of said first'or second predetermined-- Signed and sealed this 14th day of January 1975.

(SEAL) Attest:

McCOY M. 'cmsoiw JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents USCOMM-DC 603764 69 FORM PC4050 (10-69) n 1 u.s. aovzmguzm unmarorncz: nu o-ass-au,

Claims

20. A discharge head for use in a fire protection system, said head comprising a closure member normally closing said head to prevent the discharge of extinguishant from said head, first means for opening said head in response to the existence of both a first predetermined fire condition in the space to be protected and a first predetermined condition of said system, and second means for opening said head in response to the existence of both a second predetermined fire condition in said space and a second predetermined condition of said system in the event said head is not opened by said first means.

33. The system of claim 32 further comprising third means responsive to a third predetermined temperature in said space for opening said heads in the event said heads are not opened by said first means and said second means; said third predetermined temperature being higher than said second predetermined temperature.