US3064739A

US3064739A - Fire protection system

Info

Publication number: US3064739A
Application number: US39527A
Authority: US
Inventors: Eric P Hanson; Philip H Merdinyan; Gordon H Milligan
Original assignee: Grinnell Corp
Current assignee: Grinnell Corp
Priority date: 1960-06-29
Filing date: 1960-06-29
Publication date: 1962-11-20
Anticipated expiration: 1979-11-20

Description

3,064,739 FIRE PROTECTION SYSTEM Eric P. Hanson, North Providence, Philip H. Merdinyan, East Greenwich, and Gordon H. Miiligan, Pawtucket, R.I., assignors to Grinnell Corporation, Providence,

R.I., a corporation of Delaware Filed June 29, 196%, Ser. No. 39,527 Claims. (Cl. 169-2) This invention relates to improvements in fire protection systems. More particularly it has to be with a system for extinguishing fires in materials which burn so rapidly and explosively that it is essential to deliver the fire controlling and extinguishing medium to the fire in a very short time after the fire is detected if there is to be any hope of extinguishing the fire or even preventing destruction of the surrounding equipment.

There are a number of such materials which will be described herein as explosive. A precise definition is not necessary because the novelty of the present invention is not dependent upon the material which may burn. However, the serious consequences of fires in certain materials such as solid rocket fuel does dramatically demonstrate the need for an extinguishing system which is very fast.

Thus, the so-called explosive materials for which systems in accordance with the present invention are particularly useful burn so fiercely that only a short time after the fire has begun it is very large and generating a vast amount of heat. The objective is to get a controlling and extinguishing fluid onto the fire as soon as possible after it has begun so that the fluid pressures available will cause the fluid to reach the seat of the tire before it is possible for pressure produced by gases expanding away from the fire to create a barrier to fluid penetration. It is necessary for the fluid to reach the seat of the fire because very often these explosive materials contain their own combustion-supporting oxygen, and extinguishment by excluding atmosphere oxygen is not possible. Another objective is to deliver a controlling and extinguishing fluid into the region of the fire soon enough to reach valuable equipment before any interfering gas pressures can develop and in enough quantity to keep this equipment cool. Reaching this other objective constitutes a valuable advance in the fire protection system art because although the explosive material is relatively inexpensive and its complete consumption is not a substantial economic loss and although personnel may not be endangered, equipment in the region of the fire may be very expensive and diflicult to replace. Saving this equipment becomes a real benefit.

These objectives are reached by systems in accordance with the present invention each of which in general comprises a conduit leading a fire controlling and extinguishing fluid from a source under pressure to the region where the explosive material is located, a blow-ofi unit at the dischange end of the conduit, a valve which is in the conduit upstream of the blow-0E unit, which is of the kind opened by pressure after the closure member is released and which has its closure member released by a small explosive charge fired by an electrical detection circuit responsive to a fire in the material. The conduit is normally filled with the fluid between the blow-off unit and the valve at a pressure substantially lower than the supply pressure.

By this above arrangement maximum speed is achieved in getting the fire controlling and extinguishing fluid to the fire. The flow of electricity in the detection circuit to the explosive valve charge is almost instantaneous following detection. The valve charge fires immediately thereafter. The valve closure member is released in an extremely short time because the force produced by the explosive charge is created immediately and is substantial. The blow-off unit begins to move off the discharge end of the conduit immediately after the valve closure member is released, because the very first movement of this closure member in turn moves the priming fluid in the conduit downstream of the valve and since the fluid is preferably water its incompressibility causes the blow-off unit to be pushed off the conduit discharge end. As soon as the blow-off unit is out of the way the fluid can move uninterruptedly to the fire with the pressure of the supply developing a substantial velocity.

Accordingly it is one object of the present invention to provide an improved fire controlling and extinguishing system of the kind which furnishes a controlling and extinguishing fluid on the fire a surprisingly short time after detection of the fire.

Another object is to provide an improved fire controlling and extinguishing system wherein a primed conduit section is supplied through an explosively actuated valve.

Another object is to provide an improved fire controlling and extinguishing system wherein the discharge end of a section of piping has a blow-off unit, and the section is primed with fire controlling and extinguishing liquid between said end and an explosively actuated valve.

Another object is to provide an improved fire controlling and extinguishing system wherein a section of piping between a discharge nozzle and a control valve is primed with fire extinguishing medium, wherein the nozzle is provided with a blow-ofl unit, wherein the valve is opened by an explosive charge and wherein said charge is actuated by a device which detects the fire to be controlled and extinguished in its early stages.

Other objects will appear hereinafter.

The best mode in which we have contemplated applying; the principles of our improvements is shown in the accompanying drawing, but these are to be deemed merely illustrative for it is intended that the patent shall cover by suitable expression in the appended claims whatever features of patentable novelty exist in the invention dis closed.

In the drawings:

FIGURE 1 is a partially cross sectioned side elevation view of a system in accordance with the present invention showing the system protecting a mixing device for solid rocket fuel;

FIGURE 2 is a plan view taken on line 2-2 of FIG. 1;

FIGURE 3 is an enlarged cross-sectioned side elevation view of the valve in FIG. 1, showing the valve closed;

FIGURE 4 is an enlarged cross sectioned side elevation view of the blow-off unit and nozzle of FIG. 1, showing the blow-oil unit in place on the nozzle.

Referring now more particularly to the drawings, FIG. 1 shows somewhat diagrammatically apparatus 10 for mixing solid rocket fuel during one stage of its manufacture, which apparatus illustrates one environment in which there is a hazard of fire in explosive material.

At this particular stage in its manufacture solid rocket fuel is in the form of a very thick viscous liquid 12. Later on it hardens and becomes solid.

The actual mixing takes place in a bowl 13 held in a fixed position with respect to the mixing apparatus 10 by structure not shown. The mixing apparatus includes a motor and gear unit 14 driving a pair of mixing paddles 16. These paddles extend down through a protective plate 18, then through a region 20 surrounded by a skirt 22 and into the bowl 13. The bowl can be lowered from the position shown and can be moved away when mixing is completed by mechanism which is not shown.

The danger is that during mixing a fire will start in the material in the bowl, for example by one of the paddles striking a spark from a piece of tramp metal 23 which accidentally enters the material despite the great precautions taken to prevent this. Once started a fire in this material grows with tremendous speed, and if no rapid and eflective controlling and extinguishing apparatus is provided the fire completely ruins the mixing apparatus in a very short time and even the building in which this apparatus is housed.

Suitable electric eye devices 24 are mounted on the skirt 22 so as to look at the surface 26 of the material 12 being mixed. If a fire starts at or near this surface the light given off by this fire actuates the electric eye which acts like a switch and completes a circuit 28 to a small explosive cartridge or squib 30 in a valve 32 located in a pipe line 34. The cartridge is fired by this completed circuit and propels the lower end of a break joint arm 35 to the left as shown in FIG. 3 so that this arm swings clockwise about the pivot 38 at its upper end. Before this movement this break joint arm served to hold a piston rod 40 in the down position shown in FIG. 3 so that the piston 42 at the lower end of this rod closed the opening 44 within the valve body 46. The piston rod 40- extends through an opening 48 in this valve body and is provided with an O-ring seal 50 to prevent leakage. Similarly the piston 42 is provided with another O-ring 52 to prevent leakage through the opening 44 when the valve is closed.

Water is supplied to the upstream side of the valve 32 at a substantial pressure, for example, in the neighborhood of 80 pounds per square inch, while on the downstream side of the valve the pipe line 34 is primed (filled with water) but only at a slight pressure, for example two or three pounds per square inch. This pressure difierential very quickly pushes the piston 42 up into its open position when the break joint arm 36 is pushed aside by the firing of the cartridge 30 to free the piston rod 40.

In order to maintain the piping primed downstream of the valve 32 nozzles 54a and 54b inside the skirt 22 are rovided with blow-off caps 56, preferably formed of a plastic material such as polytetrafluoroethylene, and held on the nozzles by frictional engagement augmented by a snap ring 58. Sealing is further assured by an O-ring 6i). A chain 62 secures the cap to the nozzle to prevent its falling into the bowl 13 after it has been blown off.

As best shown in FIG. 2, the nozzles 54 are connected to the pipe 34 through

branch pipes

64 and 66, the latter of which penetrate the skirt portion 22 of the mixing apparatus. Four of the nozzles 54a are arranged to point to the plate 18 so that during a fire this plate is kept cool by the four streams of water. The other two nozzles 54!) are directed toward the propellant in the bowl for the purpose of controlling and extinguishing the fire. It will be understood of course that difierent numbers of nozzles 54a and 54b may be employed within the scope of the invention and that the arrangement shown in the drawings is merely a preferred arrangement.

Referring again to the nozzle shown in FIG. 4, it has been found that the type shown there is very successful, comprising a passageway 68 with a scroll 70 to 'give the water a twist and, at the discharge end of the nozzle 21 reduction in diameter at 72 followed by an outward flare at 74.

Referring again to the valve 32 the cartridge '36 is located in an extension 76 of a body cap 78 to the top of which extension the break joint arm is pivoted at 38. The body cap 78 is secured to the valve body 46 by a nut 80.

The cartridge 30 is a well known device which when placed in a holder 81 threaded into the opening 82 in the extension 76 and provided with a sufiicient electric current at its terminals explodes and by the force of its explosion moves an object held adjacent to this opening. A cartridge known as the Primer Mark 131, Model made by the Hercules Powder Company of Wilmington, Delaware, is an example of a cartridge which has been used successfully in the equipment described.

A micro-switch 84 is mounted on the valve body cap extension '76 so as to have its armature 86 actuated by movement of the break joint arm 36. This micro-switch is in a separate circuit (not shown) which gives an alarm indication that valve 32 has opened and water is flowing.

We claim:

1. A fire protection system for highly flammable materials comprising a conduit having one end adapted to be connected to a source of fire controlling and extinguishing fluid under a first pressure and extending therefrom to a discharge end at the region where said material is located; a first valve in said conduit, a second valve in said conduit upstream of said first valve; said first valve being normally closed and being opened by a fluid pressure in said conduit between said valves which exceeds a predetermined pressure lower than said first pressure; said second valve being normally closed, an explosive charge which is associated with said second valve and which when actuated opens said second valve, and means in said region and connected to said charge for detecting fire in said material and actuating said charge in response thereto; said conduit upstream of said second valve being normally filled with said fluid at said first pressure, and said conduit between said valves being normally filled with a fire controlling and extinguishing fluid at a second pressure lower than said predetermined pressure.

2. A fire protection system for highly flammable materials comprising a conduit having one end connected to a source of fire controlling and extinguishing fluid under a first pressure and extending therefrom to a discharge end at the region where said material is located;'a first valve at said conduit discharge end; a second valve in said conduit upstream of said first valve; said first valve being normally closed and being opened by a fluid pressure in said conduit between said valves which exceeds a predetermined pressure lower than said first pressure; said second valve having a closure member normally held in its closed position; an explosive cartridge which is associated with said closure member and which when fired permits movement of said closure member to its open position, and means in said region and connected to said cartridge for detecting fire in said material and firing said cartridge in response thereto; said conduit upstream of said second valve being normally filled with said fluid at said first pressure; and said conduit between said valves being normally filled with said fluid at a second pressure lower than said predetermined pressure.

3. A fire protection system for highly flammable material comprising a conduit having one end connected to a source of fire controlling and extinguishing fluid under a first pressure and extending therefrom to a discharge end at the region where said material is located; a blowofl unit normally closing said conduit discharge end; a valve in said conduit upstream of said conduit discharge end; said blow-ofi unit being blown off said conduit discharge end by a fluid pressure in said conduit between said blow-off unit and said valve which exceeds a predetermined pressure lower than said first pressure, said valve having a closure member and an operating mechanism normally holding said closure member in closed position; an explosive cartridge which is associated with said operating mechanism and which when fired moves said operating mechanism to release said closure memher; and means in said region and connected to said cartridge for detecting fire in said material and firing said cartridge in response thereto; said conduit upstream of said valve being normally filled with said fluid at said first said pressure; and said conduit between blow-oifunit and a said valve being normally filled with said fluid'at a second pressure lower than said predetermined pressure; whereby the difference in pressure between said first and second pressures opens said valve closure member when said valve closure member is released.

4. A fire protection system for highly flammable material comprising a pipe line having one end connected to a source of fire controlling and extinguishing fluid under a first pressure and extending therefrom to a discharge end at the region Where said material is located; a nozzle on said pipe line discharge end; a blow-off cap normally closing said nozzle; a valve in said pipe line upstream of said nozzle; said blow-0ft cap being forced off said nozzle by a fluid pressure therein which exceeds a predetermined pressure lower than said first pressure, said valve having a cylindrical opening, having a closure piston and having a movable operating mechanism normally holding said closure piston in said cylinder to close the valve; an explosive cartridge which is located adjacent said operating mechanism and which when fired moves said operating mechanism to release said closure piston; and means in said region and connected to said cartridge for detecting fire in said material and firing said cartridge in response thereto; said pipe line upstream of said valve being normally filled with said fluid at said first pressure; and said pipe line between said blow-ofl cap and said valve being normally filled with said fluid at a second pressure lower than said predetermined pressure; whereby the difierence in pressure between said first and second pressures moves said closure piston in said cylindrical opening to open said valve when said closure piston is released.

5. A fire protection system for highly flammable material comprising a pipe line having one end connected to a source of fire controlling and extinguishing fluid under a first pressure and extending therefrom to a discharge end at the region where said material is located; a nozzle on said pipe line discharge end; a blow-oft cap normally closing said nozzle; a valve in said pipe line upstream of said nozzle; said blow-off cap being forced off said nozzle by a fluid pressure therein which exceeds a predetermined pressure lower than said first pressure; said valve having a body with a cylindrical passage therethrough, having a closure piston within said passage, and having a member between said closure piston and said body outside said passage and holding said closure piston therein to close said valve; a chamber in said valve body outside said passage and opening adjacent said member; an explosive cartridge in said chamber and which when fired moves said member to release said closure piston; and means in said region and connected to said cartridge for detecting fire in said material and firing said cartridge in response thereto; said pipe line upstream of said valve being normally filled with said fluid at said first pressure; and said pipe line between said nozzle and said valve being normally filled with said fluid at a second pressure lower than said predetermined pressure; whereby the difference in pressure between said first and second pressures moves said closure piston in said valve passage to open said valve when said closure piston is released by movement of said member.

References Cited in the file of this patent UNITED STATES PATENTS 971,089 Stankiewicz Sept. 27, 1910 1,885,219 Bills et a1. Nov. 1, 1932 2,327,528 Kendall et a1. Aug. 24, 1943 2,570,280 Rofiman Oct. 9, 1951 2,804,929 Plummet Sept. 3, 1957 2,867,281 Donehue Jan. 6, 1959