GB2398494A

GB2398494A - Fire extinguisher

Info

Publication number: GB2398494A
Application number: GB0403554A
Authority: GB
Inventors: Roger Carr
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-02-20
Filing date: 2004-02-17
Publication date: 2004-08-25
Anticipated expiration: 2024-02-17
Also published as: GB0403554D0; GB2398494B; GB0303884D0

Abstract

A fire extinguisher comprises a hollow cylindrical body (10) sealed at one end with an integral plate in which there is a single aperture (32), a valve means (16) placed in the aperture and a plastics container (14) capable of holding fire-fighting substances. The container is held within the cylindrical body, and is in sealed engagement of the valve means. The container is thus held separately from the body and securely within the body by engaging with the valve means. A stem (36) of the valve means extends into the body, the container sealing to the stem inside the cylindrical body. This removes the risk of tampering with the connection between the valve and container which might cause in advertent release of pressurised chemicals.

Description

1 2398494 Title: Improved Fire Extinguisher

Field of the Invention

The invention relates to a fire extinguisher and a method for manufacturing such a fire extinguisher.

Background to the Invention

Fire extinguishers are generally made by welding steel to form a sealed canister with a single aperture into which a release mechanism is inserted for releasing fire controlling chemicals or water. To prevent the chemicals or water reacting with the metal canister, a lining of plastics material is formed within the canister to contain the chemicals or water.

Generally the plastics lining is provided by coating the inner surface of the canister with suitable liquid plastics material and heating so as to form a two-layer lining which coats the entire inner surface of the canister. However the process by which the plastics lining is formed in the cylinder is such that the inner lining is not always fully formed. Thus a post-forming check on the integrity of the liner is required, and a certain amount of product wastage occurs.

Over time the layers of the plastics liner separate and begin to leak chemicals or water contained therein, so causing corrosion of the outer metal canister. This means that such fire extinguishers have a short shelf life beyond which leakage will probably have occurred rendering the extinguishers dangerous to operate.

Making such fire extinguishers requires a number of different manufacturing steps including drawing of sheet steel, welding of the steel canister, forming of the plastics layer, placing the release mechanism onto the body of the canister, and filling the canister with chemicals or water at high pressure. This means that assembly of such a fire extinguisher is very labour intensive and as such expensive.

It is an aim of the present invention to provide a fire extinguisher which overcomes the disadvantages associated with the prior art, in particular the short shelf life and the labour intensive manufacture.

Summary of the Invention

In accordance with one aspect of the present invention, there is provided a fire extinguisher comprising a hollow cylindrical body sealed at one end with an integral plate in which there is a single aperture, a valve means placed in the aperture and a container capable of holding fire- fighting substances, wherein the container is held within the cylindrical body and is in sealed engagement with the valve means. The container is thus held separately from the body and securely within the body by engaging with the valve means, with the valve means in communication with the container so that the container contents can be released through the valve means when required.

The individual components comprising the fire extinguisher can be manufactured separately, so ensuring assembly of the fire extinguisher is quicker and cheaper than existing fire extinguishers. In addition, the integrity of the individual components can be inspected pre-assembly, unlike with prior art fire extinguishers where the inner plastics liner is manufactured in a forming process which has a failure rate associated with it. By using a separate pre-formed container which is then inserted into the body, there is no wastage due to failure of integrity of plastics materials in the forming stage.

Preferably a stem of the valve means extends into the body, the container sealing to the stem inside the cylindrical body. This removes the risk of tampering with the connection between the valve and container which might cause inadvertent release of pressurised chemicals.

Preferably the cylindrical body is manufactured as a single piece pressed from steel, typically by a deep draw pressing process. This avoids any welding when manufacturing the body and avoids post-welding finishing. The body can be painted directly at the steel mill after the drawing and pressing process, providing an improved finish.

Preferably the container has a neck which is sealed to the stem of the valve means by a locking ring which engages with both the stem and the neck. Desirably the neck, stem and locking ring are provided with cooperating threaded portions.

The container is preferably made of a substantially rigid plastics material, such as nylon or any suitable non-leaching plastics material, capable of withstanding high pressures. It is important that the material is non-leaching so that carbon dioxide gas or other fire-fighting substances do not leach through the container and cause corrosion of the body. By using a i non-leaching material for the plastics container which is held separately within the metal body, the shelf life of the product is dramatically improved, for example existing products often have a shelf life of one year. With the present invention, this could be as much as ten years.

The container preferably has a grip element integrally formed in its base, the grip element being used for inserting the container into the body and for holding the container whilst the locking ring is secured.

The fire extinguisher preferably further comprises a base attached to close the body.

Typically the base is secured in position after the container is sealed to the stem of the valve means, fire-fighting substances then being introduced under pressure to the sealed 'I container. The base may comprise a disc with a downturned edge attached to the body by any suitable means, for example by aligning apertures in the downturned edge and the - body and fixing the base to the body using fixing means, such as nuts and bolts, or pop rivets. Alternatively, tongues can be stamped through from the body into the downturned edge to secure the base in position. 90. (

In accordance with another aspect of the invention, there is provided a kit of parts for assembly into a fire extinguisher, the kit of parts comprising a hollow cylindrical body sealed at one end with an integral plate in which is formed a single aperture, a valve means for dispensing fire-fighting substance and a container capable of holding fire-fighting substances. The kit of parts may also comprise a separate base portion for insertion into and joining with the body.

In accordance with a further aspect of the invention, there is provided a method of manufacture of a fire extinguisher, the method comprising: taking a pre-formed hollow cylindrical body sealed at one end with an integral plate in which is formed a single aperture, placing a valve means in the aperture, placing a container capable of holding fire- fighting substances within the body and sealing the container to the valve means.

Preferably the method further comprises securing a base to an open end of the body.

The method may also comprise introducing fire-fighting substances under pressure to the container.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a fire extinguisher in accordance with the present invention; and Figure 2 is a sectional view through the fire extinguisher. ; '

Description l

A fire extinguisher in accordance with the present invention is shown in Figure 1. The fire extinguisher comprises a steel canister 10, a release mechanism 12 and a plastics container 14 or bottle (not shown) in communication with the release mechanism 12. The container 14 is capable of withstanding high pressures and is filled with fire controlling chemicals or water under pressure. The release mechanism 12 comprises a valve 16 operated by a two pronged handle 18, the handle maintained in an open and inactive position when not in use by means of a locking pin 20, and an outlet nozzle 22 to which a hose is normally i attached. The release mechanism also includes a bracket 24 for attaching the fire extinguisher to a support 26. Other types of release mechanism are possible, as those skilled in the art will appreciate. An optional seating washer 28 is colour-coded to indicate the contents of the fire extinguisher. A plastics ring 30 is fitted around the lower end of the canister, this being used for securing a dispensing hose (not shown) connected to the outlet nozzle 22.

A sectional view through the extinguisher is shown in Figure 2. The outer metal canister is of an inverted u-shaped cross section with a single central aperture 32 formed in the curved portion 34 of the canister. The canister 10 is typically formed as one integral unit by drawing and pressing sheet steel, with painting of the canister done directly at the steel mill so avoiding the need for pre-painting preparation and producing an improved paint finish over canisters welded and painted away from the steel mill. A stem 36 of the valve 16 passes through the aperture 32 and sits inside the canister. The stem has an upper externally threaded portion 36' and a lower internally threaded portion 36". O-rings 38 are seated around the outer smooth surface of the lower portion 36". The internal thread secures a siphon tube 40 which extends down into the base of the bottle 14. If necessary, the siphon tube 40 is provided with a filter 42 at one end.

The plastics container or bottle 14 is typically made from nylon or other such plastics material which is non-leaching so that the contents of the container cannot escape. The blow-moulded nylon bottle 14 has a complementary shape to that of the internal surface of the canister 10 and is arranged to have a tight fit with the canister. However there is a slight clearance between the canister and bottle as a result of internal ridging of the canister inherent in the manufacturing process associated with the canister. The bottle 14 has a grip 44 in its bottom surface and a neck portion 46 with an outer thread, typically a lazy round thread. The bottle can withstand high pressures, and can safely retain the contents under pressure.

A locking ring 48 with an internal threaded portion is also provided within the canister, the thread of the locking ring being complementary to the outer thread of the stem and the threaded neck.

Typically on assembly of such a fire extinguisher, the valve is inserted into the canister body so that the valve stem is contained within the inside of the canister. The locking ring is placed in position over the externally threaded portion of the valve and the plastics bottle, which is typically manufactured off-site by a plastics specialist, is introduced into the canister through the open base and the neck secured over the O-rings. The locking ring 48 is then tightened so as to ensure a complete seal is achieved between the container neck 46 and the valve stem 36".

If a siphon tube is required, it will have been screwed into the valve before the bottle 14is placed in position. The grip 44 in the base of the container assists with holding the container whilst the locking ring 48 is tightened.

A separate metal base 50, in the form of a shallow disc with downturned edges and which forms a tight fit with the internal surface of the canister, is pushed up into the canister with a ram. The configuration of the disc 50 is arranged to match the shape of the base of the bottle 14 once it has been secured in place and pressurised. The base plate 50 can be secured by a variety of means, these involving securing the downturned edge of the plate to the wall of the canister. The base can be secured to the canister by using nuts and bolts, rivets, or by stamping tongues of metal from the wall of the canister through into the downturned edge and folding these tongues over so as to secure the base plate in position.

To improve the appearance of the fire extinguisher, a ring 30 with a hose clip is pushed over and down the canister, until it forms an interference fit with the canister over the region where the plate is secured.

Once the base plate 50 is in position, the bottle is filled with fire controlling chemicals or water through the release mechanism 12, these contents being under pressure. The contents of the bottle may be water, foam or powder, and the bottles are of any of the capacities usual in the field, for example for liquid chemicals and water 1, 2, 3, 4, 6, 9, 12 litres and for powder 1, 2, 3, 4, 6, 9 12 kg. After filling, the release mechanism 12 acts to seal the bottle so that the contents are retained without their integrity being compromised.

This hermetic sealing, or factory sealed condition, ensures that the extinguisher has a long shelf life of at least ten years without a complex service being needed. Only inspections during the yearly service would be needed. Refilling and replacing of an extinguisher would take place at a service centre where safe environmental disposal of the chemical contents of the bottle can take place by removing the container, the remainder of the extinguisher being recycled for use with a new container. This is of advantage over existing fire extinguishers where service is yearly and involves regular discharges of the extinguisher contents at customer sites to check the extinguisher is operable. This is not very environmentally friendly and may lead to unnecessary discharges of chemicals.

The manufacture of such a fire extinguisher is achieved by using parts that are bought in pre-made from other specialist factories, which simplifies the assembly process of the fire extinguisher, improving manufacturing efficiency and reducing cost. In addition by having the valve mechanism locked in position using a locking ring within the canister body, the fire extinguishers are tamper proof. The use of a nonleaching bottle results in a vastly improved shelf life, typically with a shelf life of about ten years as opposed to the shelf life 205 for existing fire extinguishers of one year.

Claims

Claims 1. A fire extinguisher comprising a hollow cylindrical body sealed

at one end with an integral plate in which there is a single aperture, a valve means placed in the aperture and a container capable of holding fire- fighting substances, wherein the container is held within the cylindrical body and is in sealed engagement with the valve means.
2. A fire extinguisher according to claim 1, wherein a stem of the valve means extends into the body, the container sealing to the stem inside the cylindrical body.
3. A fire extinguisher according to claim 1 or claim 2, wherein the cylindrical body is manufactured as a single piece pressed from steel.
4. A fire extinguisher according to claims 2 or 3, wherein the container has a neck which is sealed to the stem of the valve means by a locking ring which engages with both the stem and the neck.
5. A fire extinguisher according to any of the preceding claims, wherein the container is made of a substantially rigid plastics material which is non-leaching of fire fighting substances.
6. A fire extinguisher according to any of the preceding claims, wherein the container has a grip element integrally formed in its base, the grip element being used for inserting the container into the body.
7. A fire extinguisher according to any of the preceding claims, wherein the fire extinguisher further comprises a base attached to close the body.
8. A fire extinguisher according to claim 7, wherein the base comprises a disc with a downturned edge attached to the body.
9. A kit of parts for assembly into a fire extinguisher, the kit of parts comprising a hollow cylindrical body sealed at one end with an integral plate in which is formed a single aperture, a valve means for dispensing fire-fighting substance and a container capable of holding fire-fighting substances.
10. A kit of parts according to claim 9, further comprising a separate base portion for insertion into and joining with the body.
11. A method of manufacture of a fire extinguisher, the method comprising: taking a pre-formed hollow cylindrical body sealed at one end with an integral plate in which is formed a single aperture, placing a valve means in the aperture, placing a container capable of holding fire- fighting substances within the body and sealing the container to the valve means.
12. A method according to claim 11, further comprising securing a base to an open end of the body.
13.A method according to claim 11 or claim 12, further comprising introducing fire- fighting substances under pressure to the container.
14. A fire extinguisher substantially as hereinbefore described and with reference to, and as illustrated in, the accompanying drawings.