US3827502A

US3827502A - Fire-extinguishing apparatus

Info

Publication number: US3827502A
Application number: US00246666A
Authority: US
Inventors: F Lockwood
Original assignee: Chubb Fire Security Ltd
Current assignee: Chubb Fire Ltd
Priority date: 1971-05-03
Filing date: 1972-04-24
Publication date: 1974-08-06
Anticipated expiration: 1991-08-06
Also published as: DE2220989A1; SE382389B; CH565675A5; GB1357010A; FR2135574A1; FR2135574B1; NL7205903A; AU4163772A; BE782957A; CA967072A; IT952810B; AU462754B2

Abstract

A fire extinguisher comprises a tube of thermoplastic material containing a fire-extinguishing liquid, the tube constituting a ''''continuous'''' detector and a continuous dispenser along the whole of its length. The strength of the tube wall is such that the tube will resist the internal pressure at ordinary temperatures but will burst at a temperature developed by a fire.

Description

United States Patent [191 Lockwood 1 Aug. 6, 1974 FIRE-EXTINGUISHING APPARATUS [75] Inventor: Frank R. Lockwood, Northwood,

England [73] Assignee: Chubb Fire Security Limited,

Sunbury-on-Thames, Middlesex, England [22] Filed: Apr. 24, 1972 [21] Appl. No.: 246,666

[30] Foreign Application Priority Data May 3, 1971 Great Britain 12698/71 Sept. 17, 1971 Great Britain 43474/71 [52] US. Cl. 169/51, 169/26 169/35, 169/62 [51] Int. Cl. A62c 3/00 [58] Field of Search 169/1 R, 2 R, 2 A, 3, 9, 169/26, 27, 35

[56] References Cited UNITED STATES PATENTS 2,585,039 2/1952 Rooke 169/26 X 2,857,971 10/1958 Ferris 169/2 R X 3,245,473 4/1966 Hita 169/2 R 3,369,346 2/1968 Wildholz et a1 169/] R X 3,486,563 12/1969 Cholin et a1. 169/26 3,509,942 5/1970 Lindberg 169/2 R Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-John J. Love Attorney, Agent, or Firm-Larson, Taylor and Hinds 5 7] ABSTRACT A fire extinguisher comprises a tube of thermoplastic material containing a fire-extinguishing liquid, the tube constituting a continuous detector and a continuous dispenser along the whole of its length. The strength of the tube wall is such that the tube will resist the internal pressure at ordinary temperatures but will burst at a temperature developed by a fire.

14 Claims, 5 Drawing Figures Hummus slam SHEET 2 BF 3 1 I FIRE-EXTINGUISHING APPARATUS In some forms of equipment housed in casings or compartments there is a serious risk of fire. Examples of such equipment include television receivers, particularly colour television receivers, radio apparatus, computers, photocopiers and business machinery, housed in cabinets. Another example is an engine housed in an engine compartment. Our object is to provide a cheap automatic fire extinguisher suitable for permanent mounting in such a casing or compartment.

An extinguisher according to the invention comprises a closed tube of thermoplastic material containing a fire-extinguishing liquid, the strength of the tube wall being such that the tube will resist the internal pressure at all ordinary ambient temperatures but will burst at a temperature developed by a fire. The strength of the tube wall will depend, for example, on the material used for the tube, its thickness and its curvature in transverse cross-section. When such an extinguisher is in use in apparatus to be protected, wherever the fire occurs within the protected space there the tube will soften and will burst and the extinguishant will be directed on to the seat of the fire. Preferably, the tube is long and flexible so that it can be mounted in a curved or curled configuration to pass over the main points of risk in the apparatus which, in general, are not located in a straight line. If the material of the tube is insufficiently flexible to bend easily in the required configuration it may be preformed. The tube is in effect a combined continuous detector and fire extinguisher, the term continuous being intended to indicate that it is an uninterrupted line detector and also an uninterrupted line dispenser for the extinguishant. It is highly advantageous to have continuous protection and uninterrupted availability of extinguishant along a line, rather than protection and extinguishant at a series of points within the apparatus to be protected.

The extinguisher may also comprise a pressure or heat-sensitive isolating device such as a pressure switch or a fuse; the isolating device can be connected to the electronic equipment or engine housed in the casing or compartment so as to stop the operation of the equipment or engine in case of fire. The isolating device may alternatively or additionally raise an alarm when the pressure in the tube falls.

Thus, in one arrangement a pressure switch closes one end of the tube and is normally held closed by the pressure within the tube but it is biased to open once the pressure falls below a predetermined value. This pressure loss may be due to the bursting of the tube as a consequence of fire or may be due to leakage if the tube is not properly sealed. Thus, the equipment or engine is unable to operate when, due to loss of pressure within the extinguisher, it is not properly safeguarded.

For larger spaces, for example for large engine compartments (particularly if there is a forced draft which cannot be switched off), the tube itself may not contain sufficient extinguishing liquid. To overcome this difficulty the tube may be connected at one end to a reservoir bottle. This arrangement still provides the same advantage of a continuous detector, permanently mounted, and dispensing of the fire extinguishant directly on to the seat of the fire.

In apparatus of the kind in question, and particularly in a television receiver, there are usually one or two specific points of risk, that is to say, points at which hot spots may develop and lead to fire. A tube according to the invention extends close to, and preferably just above, any such known points of risk. The tube should be long enough to extend across all or substantially all the electronic equipment in the cabinet or casing, and it may be looped or curved to come close to any specificpoint of risk.

The fireextinguishant is introduced into the tube in a liquid state, and to allow for expansion of it in the tube under normal fluctuations of temperature it is desirable not to fill the tube completely but to allow an ullage space. Preferably, the tube is transparent or sufficiently translucent to permit verification that it is charged ready for use by visual inspection.

A suitable thermoplastic material for the tube is nylon, for example Nylon 6.6. This material is strong at normal ambient temperatures but is weakened sufficiently under fire conditions to release the contents of the tube if these are at about 200 p.s.i. or more. The ends of the tube may be fusion-sealed or ultrasonically welded.

The liquid should have so high a vapour pressure at the expected temperature of the fire as to expel the fluid quickly.

A suitable fire-extinguishing liquid is bromo chloro difluoro methane, known as B.C.F., which has a b.p. of 4C. At 20C its vapour pressure is 38 p.s.i. (absolute) and at 90C its vapour pressure is 215 p.s.i. Thus, if this liquid is used as the fire extinguishant the tube must be sufficiently strong to withstand 38 p.s.i. and more at all ordinary ambient temperatures but be ruptured by the pressure developed at the expected temperature of the fire.

In some cases, when B.C.F. is used, local heating does not raise the pressure in the tube sufficiently to produce a rapid enough discharge. For such cases, the detector tube should be located at the top of the space to be protected so that on the occurrence of a fire the tube is heated substantially over its whole length; softening and bursting still occur selectively over the hottest part of the apparatus.

The detection time of the device can be shortened and the temperature at which it will operate can be reduced by adding to the extinguishant a suitable compatible liquid which has a lower boiling point. As an example, when B.C.F. is used as the extinguishant, the mixture within the tube may consist of percent B.C.F. and 20 percent Arcton 12.

An alternative extinguishant liquid which may be used is dibromo tetrafluoro ethane, the boiling point of which is 47C and the vapour pressure of which at C is 50 p.s.i. If this or any similar liquid of relatively low vapour pressure is used, it is desirable additionally to introduce a low boiling point liquid, as proposed for B.C.F., or a gas under pressure, preferably an inert gas such as nitrogen, so as to provide an initial pressure which is increased by the rise in vapour pressure of the liquid if fire occurs.

In order that the invention may be better understood, some examples of extinguishers embodying the invention and apparatus incorporating such extinguishers will now be described with reference to the accompanying drawings, in which:

FIG. 1 shows an extinguisher suitable for a television set;

FIG. 2 illustrates an extinguisher suitable for an engine compartment;

FIGS. 3 and 4 show diagrammatically typical arrangements of extinguisher tubes embodying the invention in television sets; and

FIG. 5 shows a typical arrangement of an extinguisher tube embodying the invention in an engine compartment.

In FIG. 1, an extinguisher 3 consists of a clear flexible tube 4 of plastics material which is filled with a halogenated hydrocarbon of which the vapour pressure increases substantially in the temperature range from room temperature upwards, for example with B.C.F. A tube having a length of 1,520 mm. and an outer diameter of 6.35 mm. may require about 40 grammes of B.C.F., the liquid-level being indicated by the line 5 in FIG. 1. For such a tube, the maximum working temperature is about 60C. In the example shown, one end 6 of the tube is closed by being ultrasonically sealed and at the other end of the tube there is a pressure switch 7 having electrical contacts 8. The pressure within the tube normally acts on the pressure switch to hold the latter open, i.e. to break the circuit between the contacts 8. When the pressure falls the switch closes to complete the electrical connection between the contacts 8 within the switch and, as stated earlier, this may be used to isolate the apparatus from the electrical supply or to raise an alarm.

The extinguisher shown in FIG. 2 is intended for apparatus such that a fire outbreak might require more extinguishant than is present in a tubular detector of the kind shown in FIG. 1. In FIG. 2, a tube 4 similar to that shown in FIG. 1 has one end connected to the outlet of a steel reservoir bottle 9, containing a backing supply of the extinguishant liquid. As before, the tube is made to run over the points of risk in the apparatus to be protected and if a fire breaks out under one portion of the tube this portion will soften and burst. The extinguishant in the tube will then be ejected on to and around the seat of the fire and fresh extinguishant from the reservoir will take the place of that expelled from the tube and will in turn be ejected onto the fire. A pressure indicator 10 is arranged on the reservoir bottle 9 in the example shown in the drawing.

The end 11 of the continuous detection-dispenser tube 4 may be sealed, as shown in the drawing, or it may complete a ring circuit back to the reservoir.

FIG. 3 shows diagrammatically the back of a television set. The main cabinet 15 has a projecting portion 16 housing most of the components associated with the cathode ray tube (not shown) and a further projecting portion 17 to accommodate the end of the cathode ray tube. The extinguisher 3, in the example shown, extends along the top of the space inside the projection 16. In the example shown in FIG. 4, however, the extinguisher 3 is looped around the upper space of the whole of the casing, including the main cabinet 15 and the projecting portion 16.

In FIG. 5, an extinguisher of the kind shown in FIG. 2 consisting of a tube 4 and reservoir 9 is placed in the engine compartment 20 of a small boat 21.

I CLAIM:

1. Fire extenguishing apparatus including a fire extenguisher comprising a single flexible continuous tube capable of being selectively positioned to conform to a desired shape relative to the thing being protected, said tube having a tube wall of thermoplastic material and containing a fire extinguishing liquid under pressure, one end of the tube being closed and the other end open, and a reservoir of the fire extinguishing liquid having an outlet connected to communicate with the open end of said tube for maintaining said tube filled with said pressurized fire extinguishing liquid, the tube being exposed throughout substantially the entire length thereof, apart from any connecting portion, so as to constitute a continuous detector and distinguisher, the said pressure and the strength of the tube wall being such that the tube will resist the internal pressure at all ordinary ambient temperatures but will burst at any point along the length thereof when said point is subjected to a temperature developed by a fire to thereupon release the contained liquid at that point.

2. A casing compartment housing equipment to be protected and including fire-extinguishing apparatus as defined in claim 1, additionally including an isolating device for connection to equipment with which the fire extinguisher is housed, said isolating device having means for connection to the said equipment and operative to stop the operation of the equipment in case of fire. 7

3. A casing compartment housing equipment to be protected and including fire-extinguishing apparatus as defined in claim 1, additionally including an isolating device for connection to equipment with which the fire extinguisher is housed, said isolating device including means for connection to said equipment and operative to initiate an alarm in case of fire.

4. A fire extinguisher comprising a single flexible continuous tube capable of being selectively positioned to conform to a desired shape relative to the thing being protected, said tube having a tube wall of thermoplastics material and containing a fire extinguishing liquid under pressure, the tube further having an external surface which is exposed substantially throughout the length thereof and constituting a continuous detector and extinguisher, the said pressure and the strength of the tube wall being such that the tube will resist the pressure of the liquid at all ordinary ambient temperatures but will soften and burst at any point along the length thereof when the said point is subjected to a temperature developed by a fire to thereupon release the contained liquid at that point.

5. A fire extinguisher in accordance with claim 4, additionally including an isolating device for connection to equipment with which the fire extinguisher is housed.

6. A fire extinguisher in accordance with claim 5, in which the isolating device comprises a pressure switch which closes one end of the tube, the switch being normally held open or closed by the pressure within the tube, the extinguisher further including biasing means arranged to close or open respectively the pressure switch once the pressure falls below a predetermined value.

7. A fire extinguisher in accordance with claim 4, in which the closed tube is of Nylon 6.6.

8. A fire extinguisher in accordance with claim 4, in which the tube is of a material permitting the passage of light to such an extent that the pressure of the extinguishing liquid can be determined by visual inspection.

9. A fire extinguisher in accordance with claim 4, in which the fire extinguishing liquid is bromo chloro difluoro methane.

10. a fire extinguisher in accordance with claim 4, in which the fire extinguishing liquid is dibromo tetrafluoro ethane.

11. A fire extinguisher in accordance with claim 10, in which the tube is partially filled with the fire extinguishing liquid and in which an inert gas is also present.

12. A fire extinguisher in accordance with claim 4, in which the tube is partially filled with a fire extinguishisolating device.

Claims

2. A casing compartment housing equipment to be protected and including fire-extinguishing apparatus as defined in claim 1, additionally including an isolating device for connection to equipment with which the fire extinguisher is housed, said isolating device having means for connection to the said equipment and operative to stop the operation of the equipment in case of fire.

12. A fire extinguisher in accordance with claim 4, in which the tube is partially filled with a fire extinguishing liquid to which has been added a compatible low boiling point liquid.

13. A casing or compartment housing equipment to be protected and including a fire extinguisher in accordance with claim 5, in which the isolating device has means for connection to the said equipment and operative to stop the operation of the equipment or to initiate an alarm in case of fire.

14. A fire extinguisher in accordance with claim 5 wherein said isolating device comprises a heat-sensitive isolating device.