US3780811A

US3780811A - Method of fire protection using recirculation of combustion products

Info

Publication number: US3780811A
Application number: US00277495A
Authority: US
Inventors: Yao Cheng
Original assignee: Factory Mutual Research Corp
Current assignee: Factory Mutual Research Corp
Priority date: 1971-11-12
Filing date: 1972-08-03
Publication date: 1973-12-25
Anticipated expiration: 1990-12-25

Abstract

A method for fire protection wherein a nozzle discharges an extinguishant in response to a predetermined fire condition in a manner to create an aspiration effect which circulates the combustion products from the fire in a path including the fire. The circulation of the combustion products is terminated and the rate and manner of discharge of extinguishant from the nozzles can be changed in response to an additional predetermined fire condition.

Description

3a780a8ll United States Patent [191 Yeo X [451 Dec.25,1973

METHOD OF FIRE PROTECTION USING RECIRCULATION OF COMBUSTION PRODUCTS Inventor: Cheng Yao, Weston, Mass.

[73] Assignee: Factory Mutual Research Corporation, Norwood, Mass.

[22] Filed: Aug. 3, 1972 [211 Appl. Noi: 277,495

Related US. Application Data [62] Division of Ser. No. 198,386, Nov. 12, 1971, Pat. No.

[52] US. Cl. 169/12, 169/1 A [51] Int. Cl. A62c 35/00 [58] Field of Search 169/1 A, 5-18 [56] References Cited UNITED STATES PATENTS 2,498,512 2/1950 Thompson 169/12 l2 b I 6 3,463,234 8/1969 Van Baak 169/12 X Primary Examiner--M. Henson Wood, Jr. Assistant Examiner-John J. Love Attorney-JosephM. Lane et a].

57 ABSTRACT A method for fire protection wherein a nozzle dis- I charges an extinguishant in response to a predetermined fire condition in a manner to create an aspirav tion effect which circulates the combustion products from the fire in a path including the fire. The circulation of the combustion products is terminated and the rate and manner of discharge of extinguishant from the nozzles can be changed in response to an additional predetermined fire condition.

l0 Claims, 3 Drawing Figures METHOD OF FIRE PROTECTION USING RECIRCULATION OF COMBUSTION PRODUCTS This application is a division of application Ser. No. 198,386, filed Nov. 12, 1971, now U.S. Pat. No.

CROSS REFERENCE TO RELATED APPLICATION This application relates to U.S. Pat. application Ser. No. 131,988, now U.S. Pat. No. 3,692,118, filed on Apr- 7, 1971, by the same inventor as the present invention and assigned to the same assignee as the present invention. The disclosure of the latter application is hereby incorporated by reference.

BACKGROUND OF THE INVENTION This invention relates to a method for fire protection, and more particularly to such a method which utilizes the products of combustion from a fire to aid in extinguishing the fire. The method includes a discharge device and method for achieving the above.

In the above-mentioned related application Ser. No.

Towards the fulfillment of these and other objects of the present invention, the method'of the present invention BRIEF DESCRIPTION OF THE DRAWINGS Comprises the steps of discharging extinguishant towards a fire, circulating the combustion products from the fire in a path including the fire and terminating the circulation of combustion products while maintaining the extinguishant discharge.

, 2-2 of FIG. I; and

131,988, a fixed fire extinguishing system is disclosed in which the combustion products of a fire developing in the enclosure to be protected are circulated back towards the fire at the early stage of the fire development to prevent the ingress of air to the fire. The circulation of the combustion products is achieved by the use of a plurality of aspiration-type nozzles which are mounted near the ceiling of the enclosure, with each having an inlet opening for receiving the products of combustion and a discharge opening for discharging the products of combustion. When actuated, the nozzles discharge an extinguishant towards the fire which creates an aspiration effect and circulates the products of combustion in a path upwardly from the fire,

through the nozzles, and downwardly into the fire. In this manner, air entering the building through its windows and doors and passing towards the fire is blocked by the barrier created by the products of combustion.

Although the above arrangement was found to be effective in extinguishing fires, it suffered from the fact that the extinguishant discharge velocity from the nozles had to be set at a relatively high value in order to obtain the aspiration effect. Since this was accomplished by utilizing a relatively small discharge opening, the extinguishant discharge from the nozzles was ineffective in directly fighting the fire, since it was unable to penetrate the fire plume. This, of course, imposed limitations on the fire-fighting capability of the system, especially in fire situations in which the recirculation of the combustion products around the fire could not achieve total fire extinction. I

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method of the above type in which the combustion products from the fire are circulated in a path.

including said fire, with the circulation being termi nated locally in response to additional information received from the fire.

It is a further object of the present invention to provide a method for fighting a fire in which the rate and manner of discharge from the nozzles is altered upon the termination of the circulation of the combustion products.

FIG. 3 is a view similar to FIG. 1, but showing the device of the present invention after responding to a fire condition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The discharge device utilized in the method of the present invention is depicted in FIG. 1 of the drawings, and includes a nozzle unit 10 defining a discharge outlet lGa at its lower end as viewed in FIG. 1 and having a T-shaped coupling member 12 threadably connected to its upper end. One end portion of the coupling member 12 is internally threaded as shown at 12a for connection to a branch line 13 for supplying an extinguishant such as water, it being understood that a typical fire protection system will include several discharge devices and branch lines, along with submains, risers. and a main, to supply the branch lines with an extinguishant, such as water, in a conventional manner, and as shown and described in the above-mentioned related application.

A closure plug 14 is threadably engaged in the other end portion 12b of the coupling member 12 and defines a central opening which receives a valve stem 16 slidably extending therethrough. A valve head 18 is connected to one end of the valve stem 16 and is adapted to engage a cooperating seat 20 supported by the internal wall of the coupling member 12 to block the flow" of extinguishant through the coupling member.

A lever arm 22 is pivotally mounted to the plug 1 4 V and is adapted to be connected, by means of a fusible link 24, to a lever arm 26 fixed with respect to the plug. The pivotal lever arm 22 has aprojection engaging the other end of thevalve stem 16 to maintain the valve head 18 against the seat 20 as long as the fusible link 24 maintains the connection between the levers 22 and A circumferential groove 34 is formed in the outer periphery of the nozzle unit 10 for reasons that will be explained in detail later.

An open-ended, hollow housing 40, formed in the shape of a venturi, extends over the bottom portion of the nozzle unit 10 and has an inlet 40a and an outlet 40b for respectively receiving and discharging the products of combustion from the fire. An extension 42 for the discharge opening 100 is mounted relative to the housing 40 by means ofa plurality of struts 44, two ofwhich are shown in FIG. 1. The extension 42 extends over the discharge end portion of the nozzle unit 10 and has a discharge opening 420 which registers with the discharge outlet a, with the opening 42a being of a smaller diameter than the outlet-10a. In an exemplary embodiment of the present invention, the outlet 10a would have a diameter of approximately one-half inch and would discharge the extinguishant at a spray angle of approximately l50 degrees, while the opening 42a would have a diameter of approximately one-eighth of an inch and would discharge the extinguishant at a spray angle of approximately l00 degrees.

The housing 40 is connected relative to the nozzle unit 10 by means of three substantially L-shaped con-' necting arms 50. Each of the arms 50 consists of a lower portion 500 which engages underneath an inwardly-directed circular flange 400 formed on the upper end of the housing 40, and an upper portion 50b which engages a split ring 52 extending around the upper end portion of the nozzle unit 10 and having its ends normally connected by a fusible link 54. The elbow portions of the arms 50 are supported by, and extend within, the circumferential groove 34.

Referring specifically to FIGS. 1 and 2 for a better view of the interconnection between the upper arm portions 50b and the ring 52, it is seen that the arm portions are curved slightly at their upper ends so that they extend around, and over, the top surface of the ring. In this manner the ring 52 can be designed to maintain the arms 50 under a slight, inwardly-directed spring tension in order to maintain the arms, and therefore the housing 40, in the position shown in FIG. 1. Of course, when the link 54 fuses in response to a predetermined temperature, the ends of the ring are free to separate, which will release the arms 50 and therefore permit the housing 40 to fall from the nozzle 10 under the force of gravity.

The temperatures required to fuse the fusible link 24 and the fusible link 54 may vary in accordance with particular design considerations. A preferred embodiment would have the fusible link 54 adapted to fuse at a temperature greater than the fusible link 24, with a specific example of the fusing temperatures being 165F. for the link 24 and 500F. for the link 54.

As an example of the method of the present invention and using water as an example of the extinguishant, upon the temperature in the vicinity of the fusible link by the extension 42. This relatively high velocity is sufficient to induce the products of combustion from the fire to enter the housing 40 through its inlet 40d. This, plus the venturi shape of the housing 40, createsan aspiration effect which circulates the products of combustion from the fire in a path from the-fire, downwardly through the inlet 40a, and outwardly from the housing through the outlet 40b. In this action the water is atomized into a fog, a large portion of which circulates with the combustion products in the above manner. As emphasized, in the above-cited application, this circulation of the combustion products creates a barrier which prevents air entering the building through doors, windows, etc., from passing directly into the fire. As a result, the fire will be smothered and rendered relatively easy to extinguish.

In the event the above circulation of combustion products does not completely extingui the fire, and assuming the fire causes the tempe ne vicinity of the device to increase to approximately 500F., the fusible link 54 will collapse, permitting a release of the. split ends of the ring 52 and a release ,of the arms from the ring. The housing 40 will thus be released from the position shown in FIG. 1 and will fall away from the nozzle unit 10. As a result, the device will take the operational position shown in FIG. 3, with the extinguishant flowing directly into the nozzle unit 10 and being directly discharged from the relatively large outlet 100 at a relatively high rate and wide spray angle. Thus, in the latter operational mode of the device, the above-mentioned aspiration effect will be eliminated and the rate of extinguishant discharge and the area of coverage will be increased.

Of course, in a system incorporating several of the discharge devices, it is apparent that, in a typical highchallenge fire situation, the discharge devices directly over the fire may attain their direct discharge mode while the peripheral devices will circulate the combustion products in the above manner. As a result the former devices will have a relatively good chance of extinguishing the fire directly since the latter devices will prevent the ingress of air to the fire. As a result. optimum fire fighting capability is achieved.

It is understood that the invention is not limited to the use of water as an extinguishant, but can incorporate other extinguishants that lend themselves to the above operation. For example, a water based foam forming fluid may be used in accordance with the fore- 24 reaching lF.,the link will collapse and permit a i pivoting of the arm 22 relative to the arm 26 under the force of the valve stem 16 as a result of the water pressure acting against the valve head 18. This permits the .and a relatively narrow spray angle due to the presence of the relatigiy srnall discharge opening 420 provided going. An example of the latter would be a mixture of water and a foaming compound such as any one of a number of synthetic surface active agents that are stable with the fire products of combustion. The foaming compound could be injected into the waterline in re-- sponse to a fire situation and the resulting fluid, when discharged through the outlet 42a in accordance with the foregoing, would create the aspiration effect discussed above and induce the products of combustion into the housing 40. The resulting mixture of the solution and the combustion products would cause the foaming compound to foam, with the compound preferably being such that the resulting foam would consist of between 200-1000 parts combustionv products to 1 part of water by volume. Of course, upon the fusing of the links 54 and the resulting release of the housing 40 and discharge of the fluid from the larger outlet 10a. the fluid would remain it its fluid state and would discharge directly to the fire in a spray of droplets with the said space greater than said predetermined temperature.

3. The method of claim 1 further comprising the steps of forming a foam in response-to said step of cirvided to each nozzle after a predetermined time delay,

can be incorporated in the system of the present invention. Also, the sizes of the outlet 10a and the opening 42a, as well as the fusing temperatures for the

links

24 and 54, may be varied in accordance with the present invention.

Still other variations of the specific construction and arrangement of the method disclosed above can be made by those skilled in the art without departing from the invention as defined in the appended claims.

1. A method of fighting a fire comprising the steps of discharging extinguishant towards said fire, circulating the combustion products from said fire in a path including the fire, and terminating said circulation of combustion products while maintaining said extinguishant discharge.

2. The method of claim 1 wherein said steps of discharging and circulating are done in response to a predetermined temperature in the space to be protected from fire, and wherein said steps of terminating and maintaining are done in response to a temperature in lating and discharging said culating and discharging said foam towards said fire.

4. The method of claim 3 wherein said extinguishant is a foam forming fluid, wherein said step of circulating causes the foaming of said fluid, and wherein the discharge of said fluid is increased in response to said step of terminating. 1

5. The method of claim 1 wherein said extinguishant is water, wherein said step of circulating causes said water to atomize, and wherein the discharge of said water is increased in response to said step of terminating.

6. The method of claim 1 further comprising the step of changing the spray angle of said discharge.

7. The method of claim 1 further comprising the step of changing the rate of extinguishant discharge.

8. A method of fighting a fire comprising the steps of circulating the combustion products from said fire in a path including said fire in response to a predetermined temperature existing in the space to be protected, and terminating said circulation of combustion products in response to a temperature existing in said space greater than said predetermined temperature.

9. The method of claim 8 further comprising the steps of forming a foam in response to said step of cir-- culating and discharging said foam towards said fire.

10. The method of claim 8 further comprising the steps of forming a fog in response to said step of circufog towards said fire. 8 t

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 r 1 D t d December 25 1973 Inventor (s) Chang Yao It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lines 'l-ll, cancel and rewrite as follows:

-Towards the fulfillment of these and other objects of the present invention, the method of the present invention comprises the steps of discharging 'extinguishant towards a fire, circulating the combustion products from the fire in a path including the fire and terminating the circulation of combustion products while maintaining the extinguishant discharge.

BRIEF DESCRIPTION OF THE DRAWINGS Reference is now made to the accompanying drawings-- Column 2, lineIZ, cancel "ings" Signed and sealed this 30th day of April l97l4..'

(SEAL) Attest:

EDWARD HELETCHEPLJR. ,C. I LARSHALL 'DAH'Z-I Attestin-g Officer Commissioner of Patents

Claims

2. The method of claim 1 wherein said steps of discharging and circulating are done in response to a predetermined temperature in the space to be protected from fire, and wherein said steps of terminating and maintaining are done in response tO a temperature in said space greater than said predetermined temperature.

3. The method of claim 1 further comprising the steps of forming a foam in response to said step of circulating and discharging said foam towards said fire.

4. The method of claim 3 wherein said extinguishant is a foam forming fluid, wherein said step of circulating causes the foaming of said fluid, and wherein the discharge of said fluid is increased in response to said step of terminating.

9. The method of claim 8 further comprising the steps of forming a foam in response to said step of circulating and discharging said foam towards said fire.

10. The method of claim 8 further comprising the steps of forming a fog in response to said step of circulating and discharging said fog towards said fire.