US3834462A

US3834462A - Automatic fire protection system for low temperature environments

Info

Publication number: US3834462A
Application number: US00336604A
Authority: US
Inventors: L Orloff; Ris J De; J Coons
Original assignee: Factory Mutual Research Corp
Current assignee: Factory Mutual Research Corp
Priority date: 1973-02-28
Filing date: 1973-02-28
Publication date: 1974-09-10
Anticipated expiration: 1991-09-10

Abstract

A fire extinguishing system for low temperature environments in which a network of pipes are supported in an elevated position in the space to be protected and are connected to a source of extinguishant. A plurality of thermally operable extinguishant discharge heads are connected to the network of pipes and are adapted to open in response to a predetermined fire condition in the space. A control valve normally prevents the flow of extinguishant to the network of pipes, and is responsive to the opening of one or more of the heads for permitting the flow of extinguishant to the network of pipes. One or more common drain lines are connected to the pipes in the network for permitting the flow of extinguishant through all of the pipes upon the opening of one or more of the heads.

Description

United States Orloii et a1.

atent 1 AUTOMATIC FHRE PROTECTION SYSTEM FOR LOW TEERATURE ENVIRONMENTS [75] Inventors: Lawrence Orloff, Foxboro; John N.

DeRis, Sharon; John D. Coons, Norwood, all of Mass.

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

[22] Filed: Feb. 28, 1973 [21] Appl. No.: 336,604

11] 3,834,662 Sept. 10, 1974 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-John J. Love Attorney, Agent, or FirmLane, Aitken, Dunner & Ziems; Warren B. Kice [57] STRACT A fire extinguishing system for low temperature environments in which a network of pipes are supported in an elevated position in the space to be protected and are connected to a source of extinguishant. A plurality of thermally operable extinguishant discharge heads are connected to the network of pipes and are adapted to open in response to a predetermined fire condition in the space. A control valve normally prevents the flow of extinguishant to the network of pipes, and is responsive to the opening of one or more of the heads for permitting the flow of extinguishant to the network of pipes. One or more common drain lines are connected to the pipes in the network for permitting the flow of extinguishant through all of the pipes upon the opening of one or more of the heads.

10 Claims, 2 Drawing Figures AUTOMATIC FIRE PROTECTION SYSTEM FOR LOW TEMPERATURE ENVIRONMENTS BACKGROUND OF THE INVENTION This invention relates to a fire protection system, and, more particularly, to an automatic fixed fire protection system which is especially adapted for use in low temperature environments such as food warehouses and the like.

A great majority of fire protection systems now in use employ a plurality of thermally operated sprinkler heads connected to a piping network located in an elevated position in the space to be protected. The heads are individually actuatable in response to a predetermined temperature in their vicinity and are adapted to discharge an extinguishant, usually in the form of water, towards the fire. In these systems, the water is usually allowed to remain in the piping network during inaction of the system in order to increase the response time.

However, it can be appreciated, that, under most low temperature environments, such as in large freezers, food warehouses, or the like, the water maintained in the piping network during inaction of the system will freeze and cause a plugging of the system.

Attempts have been made to overcome this defect in traditional fire extinguishing systems when applied to low temperature environments by utilizing what is commonly known as a dry-pipe system. In these arrangements, the piping network is kept free of water and a valve is usually connected to the main riser for supplying the network. The valve is normally closed and, upon the occurrence of a fire condition in the space to be protected, is adapted to open to allow the extinguishant to flow to the piping network.

However, this system also suffers from a major disadvantage due to the low temperature environment. In particular, when the occurrence of a fire condition in the space to be protected is sufficient to actuate the main control valve and one or more sprinkler heads, water will flow to all of the pipes in the piping network despite the fact that only a relatively low number of heads have been actuated due to their proximity to the fire. Therefore, the water flowing into portions of the piping network having heads that are not actuated due to their relatively remote location from the actual fire, will tend to freeze due to the low temperature environment, and, therefore, plug up this portion of the piping network. This is especially disadvantageous when the fire later spreads to this remote portion of the space to the extent that it actuates one or more heads in this latter area, since the flow of extinguishant through these heads would be prevented due to the ice.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an automatic fixed fire protection system for protecting low temperature environments in which the piping network is normally kept in a dry state during inaction.

It is a further object of the system of the present invention to provide a system of the above type in which extinguishant flow occurs through all of the branches of the piping network upon the existence of a fire condition in the space despite the fact that only a selected, relatively low, number of heads are actuated.

Toward the fulfillment of these and other objects, the system of the present invention comprises a network of pipes supported in an elevated position in the space to be protected, a plurality of extinguishant discharge heads connected to said network of pipes, means responsive to a predetermined fire condition in said space for selectively actuating said heads, control means for normally preventing the flow of extinguishant from a source to said network of pipes, said control means being responsive to a predetermined fire condition in said space for permitting the flow of extinguishant from said source to said network of pipes, and at least one common drain line connected to the pipes in said network of pipes for permitting the flow of extinguishant through each pipe upon actuation of one or more of said heads. I

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view, partially schematic, depicting the automatic fixed fire protection system of the present invention as installed in a building, and

FIG. 2 is an enlarged front elevational view depicting a discharge head utilized in the system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of the drawings, a building 10 is shown inphantom lines which is equipped with the automatic fixed fire protection system of the present invention. A buried feed main I2 is connected to a municipal water supply line 14 for delivering extinguishant, in this case water, to a riser 16 which is provided with a control valve 18 and which is connected to a cross main 20 extending generally horizontally for the entire length of the building 10. The valve 18 controls the flow of water through the riser l6 and operates in response to a predetermined pressure differential occurring thereacross as will be described in detail later.

A plurality of branch lines 22 extend perpendicularly to the cross main 20 and are connected at the one end thereto. A plurality of extinguishant discharge heads 24 are connected in an upright position in a spaced relation along each branch line 22.

A typical discharge head 24 is shown in detail in FIG. 2 and consists of a body portion 26 and a yoke 28 extending from the body portion and supporting a serrated deflecting disc 30. A plug 32 normally blocks an opening extending through the body portion 26, with a pair of levers 34a and 34b extending between the plug 32 and the yoke 28 and supporting the plug in the position shown by means of a fusible link 35. The fusible link 35 is adapted to fuse, or melt, at a predetermined temperature for releasing the levers 34a and 34b and therefore the plug 32, which permits the discharge of water from the head 24 under the conditions described in detail later. It is emphasized that other types of upright discharge heads such as glass bulb or chemical pellet actuated heads are also suitable in the environment of the present invention.

A source of compressed air is shown in general in FIG. 1 by the reference numeral 36, and is connected to the riser 16 for admitting pressurized air into the system. The design of the control valve 18 is such that, with the heads 24 in their normal closed position, the resulting air pressure acting on the upper portion of the valve 18 as viewed in FIG. 1, is sufficient to maintain the valve in a closed position against the pressure of the water acting on the lower portion of the valve. However, when the air pressure in the system is relieved in response to the opening of one or more of the heads 24, the valve will open to permit the water to flow through the riser 16, the cross main 20, and into each branch line 22. Since the valve 18 is of a conventional design, it will not be described in any further detail.

A pair of drain lines 38 are provided in a parallel spaced relationship to the cross main 20 and are connected to the other ends of their corresponding branch lines 22 to receive water therefrom. The free ends of the drain lines 38 are connected to a pair of drain risers 40 which have end portions 49a connected to a drain or the like (not shown). A pair of drain valves 42 are provided in the end portions of the drain lines 38 near their respective connections with the drain risers 40. The drain valves 42 are normally closed to prevent the flow of fluid through their respective drain lines 38 in order to permit the system to be pressurized as discussed above, but are adapted to open to permit the flow of extinguishant therethrough. As an example of the manner in which the drain valves 42 can operate, they can be of a solenoid operated design and can be electrically connected to the control valve 18 as shown by the dashed lines for opening in response to the opening of the latter valve. Since this type of design and operation is conventional, it will not be described in any further detail.

A valve 44 is provided in each branch line 22 near the end portion thereof for permitting testing of the respective branch lines. This can be achieved by making the valve 44 in the form of a small ball valve of the like which is normally open but which can be manually closed. In this manner, the valves 44 in all of the branch lines but one can be closed, and air can be passed through the open line to test for obstructions, and the procedure repeated for the other lines.

in operation, the system is charged with air from the source 36 at a pressure sufficient to maintain the control valve 18 closed. Upon the occurrence of a predetermined fire condition, one or more of the heads 24 in the immediate vicinity of the fire will open which relieves the air pressure in the system. As a result, the control valve 18, and therefore the drain valves 42 will open, permitting the flow of extinguishant under pressure throughout the entire piping network consisting of the cross main 20, the branch lines 22, and the drain lines 38. Although water discharge will be effected only through one or more of the heads 24 on one or more of the branch lines 22, depending on the proximity of the heads to the fire, extinguishant flow will be permitted through all of the branch lines 24 and into the drain lines 38 for drainage through the drain risers 40. This, of course, permits continuous circulation of extinguishant through the system even though no heads on a particular branch line or lines open, which avoids any freezing of the extinguishant in the piping network and the resultant plugging of the pipes.

It is noted that the branch lines 22 slope slightly towards their respective drain lines 38 and that the latter also slope toward their respective drain risers 40, so that the residual water may be drained from the system when the water supply is shut off.

It is understood that several modifications may be made in the foregoing without departing from the scope of the invention. For example, the electrical connection between the control valve 18 and the drain valves 42 may be eliminated and the latter valves may be in the form of spring loaded relief valves which can be set to open at a value slightly above the normal air pressure in the system so that they will open when water pressure is applied to the system in response to the opening of main control valve 18.

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

We claim:

1. A fixed fire extinguishing system comprising a source of extinguishant, a network of pipes supported in an elevated position in the space to be protected, connecting means for connecting said source of extinguishant to said network of pipes, a plurality of extinguishant discharge heads connected to said network of pipes, each head being normally closed and being adapted to open in response to a predetermined fire condition in its vicinity, a control valve disposed in said connecting means, said control valve being normally closed to prevent the flow of extinguishant from said source to said network of pipes and being adapted to open in response to the opening of one of said heads to permit said flow of extinguishant, at least one common drain line connected to the pipes in said network of pipes for permitting the flow of extinguishant through each pipe upon opening of at least one of said heads, and valve means cooperating with said drain line for normally preventing the flow of extinguishant through said drain line, said latter valve means being responsive to the opening of said control valve for permitting the flow of extinguishant through said drain line.

2. The system of claim 3 wherein said connecting means comprises a riser connected to said source of extinguishant and wherein said network of pipes comprises a cross main connected to said riser and a plurality of branch lines extending perpendicular to said cross main and connected at one end to said cross main, and wherein there are two drain lines connected to the other ends of said branch lines.

3. The system of claim 1 further comprising manually operable valve means in said pipes to control the flow of fluid through said pipes.

4. The system of claim 1 further comprising a thermal responsive member connected to each head and responsive to a predetermined temperature for opening said head in accordance with its proximity to a fire occurring in said space.

5. The system of claim 1 further comprising means to charge said network of pipes with pressurized air, said control valve being closed by the force of said pressurized air and being adapted to open in response to the venting of said air resulting from the opening of at least one of said heads.

6. A fixed fire extinguishing system comprising a source of extinguishant, a network of pipes supported in an elevated position in the space to be protected, connecting means for connecting said source of extinguishant to said network of pipes, a plurality of extinguishant discharge heads connected to said network of pipes, each head being normally closed and being adapted to open in response to a predetermined fire condition in its vicinity, a control valve disposed in said connecting means, said control valve being normally closed to prevent the flow of extinguishant from said source to said network of pipes and being adapted to open in response to the opening of one of said heads to permit said low of extinguishant, at least one common drain line connected to the pipes in said network of pipes for permitting the flow of extinguishant through each pipe upon opening of at least one of said heads, and valve means cooperating with said drain line for normally preventing the flow of extinguishant through said drain line, said later valve means being responsive to a predetermined pressure in said drain line for permitting the flow of extinguishant through said drain line.

7. The system of claim 6 wherein said connecting means comprises a riser connected to said source of extinguishant and wherein said network of pipes comprises a cross main connected to said riser and a plurality of branch lines extending perpendicular to said cross main and connected at one end to said cross main, and wherein there are two drain lines connected to the other ends of said branch lines.

8. The system of claim 6 further comprising manually operable valve means in said pipes to control the flow of fluid through said pipes.

9. The system of claim 6 further comprising a thermal responsive member connected to each head and responsive to a predetermined temperature for opening said head in accordance with its proximity to a fire occurring in said space.

10. The system of claim 6 further comprising means to charge said network of pipes with pressurized air, said control valve being closed by the force of said pressurized air and being adapted to open in response to the venting of said air resulting from the opening of at least one of said heads.

v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,834,462 September 10, 1974 Patent No. Dated r LAWRENCE ORLOFF, JOHN DERIS and JOHN COONS Inventor(s) 1 c It is certified that error appears in the ebove-identified patent and that said 'Letters Patent are hereby corrected as' shown below:

Cleim 2, column 4, line '37, "claim. 3 wherein" should read vclaim 1 wherein .7

Signed and sealed this 17th dayof December 1974.

(SEAL) Attest: I

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer I Commissioner of Patents