GB2300564A

GB2300564A - Portable fire extinguisher

Info

Publication number: GB2300564A
Application number: GB9513701A
Authority: GB
Inventors: Roger Carr; Graham Beckett
Original assignee: UK FIRE INTERNATIONAL Ltd
Current assignee: UK FIRE INTERNATIONAL Ltd
Priority date: 1995-04-13
Filing date: 1995-07-05
Publication date: 1996-11-13
Also published as: AU695974B2; GB9507716D0; AU5064796A; GB9513701D0

Abstract

A fire extinguisher which dispenses liquid based extinguishant is characterised by the extinguishant being housed in a collapsible vessel which is typically a plastic bag (12). The contents of the bag are pressurised to be expelled from the extinguisher (1) by filling the void space (2) of the area surrounding the bag (12) with pressurised gas. The extinguisher is immune to its disposition when in use and can be tilted or completely inverted if needed.

Description

IMPROVED PORTABLE FIRE EXTINGUISHER Field of the Invention The present invention relates to portable fire extinguishers primarily of the type which are liquid-dispensing hand-held and have a short outlet nozzle.

Background to the Invention Fire extinguishers of the type referred to above are severely handicapped in operation by the circumstances where it would otherwise be desirable to invert the extinguisher or tilt it on its side to approach the nozzle to the source of the fire. Of particular note is the fact that portable fire extinguishers installed on aircrafts are vulnerable to the attitude of the aircraft in flight to the extent that their operation cannot be relied upon.

Furthermore, problems arise with the existing fire extinguishers in circumstances where there is restricted access, e.g under a vehicle instrument facia or seating.

Accordingly, there is a need for a design of portable fire extinguisher that overcomes this attitude sensitivity of the conventional design. It is a general object of the present invention to provide such an extinguisher.

Summarv of the Invention According to the present invention there is provided a portable fire extinguisher of the type which dispenses a liquid based fire extinguishing material, the extinguisher being characterised in that the fire extinguishing material is accommodated within the body of the fire extinguisher inside a collapsible vessel within the body of the fire extinguisher and in that the contents of the vessel are pressurised to be expelled by the fire extinguisher in use by pressurisation of the chamber within the fire extinguisher body surrounding the exterior of the vessel.

Preferably the collapsible vessel is a bag.

Advantageously the bag is a plastics bag.

Preferably the plastics bag is composed of a laminate of plastics and aluminium.

Advantageously the vessel is adapted to be releasably secured in a gas and liquid tight fashion to the feed or siphon tube of the head of the fire extinguisher.

According to a second aspect of the present invention there is provided a method of filling a portable fire extinguisher which comprises providing a portable fire extinguisher of the invention; charging the fire extinguisher with fire extinguishing material through the outlet nozzle of the fire extinguisher and thence through the delivery tube of the fire extinguisher head into the vessel; and then supplying a pressurising gas through a pressurisation port in the body or head of the fire extinguisher into the void between the vessel and the internal wall of the chamber of the fire extinguisher body to place pressure on the outside of the vessel and thereby pressurise the contents thereof.

Although it is known to store the fire extinguishing materials in large static fire extinguishing storage tanks using a bag liner within those tanks, the purpose of the bag lining in those cases is to serve as an anti-corrosion measure to avoid the need for painting of the interior of the storage tank.

By providing the collapsible bag within the fire extinguisher body that is pressurised externally of the bag the fire extinguisher is rendered immune to its attitude when in use and can be used tilted or totally inverted if desired.

Brief Description of the Drawings The preferred embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, wherein the accompanying Figure 1 is a side elevation of a preferred embodiment of fire extinguisher and in which the body of the fire extinguisher is shown cut away to illustrate the internal construction thereof.

Description of the Preferred Embodiment Referring to Figure 1, the fire extinguisher thereshown is of a generally conventional type comprising a broadly cylindrical body 1 having an internal chamber 2 to receive the liquid fire extinguishing material which may, for example, be aqueous film forming (AFF) foam or the like. The extinguisher has a primary opening 4 at one end thereof that is plugged by the fire extinguisher head 3.

The fire extinguisher head 3 comprises a collar-shaped member 5 that screw mounts within the screw threaded neck of the opening 4. The extinguisher head 3 further comprises a central member 6 which seats within the bore of the collar 5 and has a delivery tube 7 extending down into the chamber 2 of the body 1 while the outermost part of the central member 6 is integrally moulded to provide an outlet nozzle 8 and trigger handle 9 which controls emission of the fire extinguishing material from the fire extinguisher by intermediacy of a control valve (not shown).

A conventional gauge 10 is also provided on the fire extinguisher head 3 to provide the necessary indication of the internal pressure of the fire extinguisher.

Also provided in the collar-shaped member 5 of the fire extinguisher head 3 is a passage that extends from the exterior to the interior of the body 1 and which is fitted with a non-return tank valve 11 to enable selective introduction of gas under pressure to pressurise the interior of the container 1.

In the conventional fire extinguisher the fire extinguishing material is charged into the chamber 2 within the body 1 directly through the primary opening 4 or through the internal bore of the collar-shaped member 5 of the fire extinguisher head 3. Pressurised gas, most commonly nitrogen or dry air, would then be pumped through the tank valve 11 into the chamber 2 and mixing with the fire extinguishing liquid to pressurise the contents of the chamber 2 which is otherwise completely sealed off by the fire extinguisher head 3 and its integral control valve. When subsequently required for use, operation of the trigger handle 9 releasing the control valve would allow the pressurised fluid within the chamber 2 to be dispensed up through a siphon tube extension of the tube 7 of the fire extinguisher head 3 and out through the emission nozzle 8.

In the case of the illustrated preferred embodiment of the present invention, the tube portion 7 of the fire extinguisher head 3 that extends into the chamber 2 of the body 1 has a bag 12 fitted thereto, the interior of which is in direct fluid communication with the interior of the tube 7.

The bag 12 acts as the storage receptacle that stores the fire extinguishing material which is introduced into the fire extinguisher through the nozzle 8 and thence through the tube 7 into the bag 12.

The bag 12 is suitably a plastics and aluminium laminate bag otherwise widely available and known as a Lucas bag. Bags of this type are relatively non-corrosive and robust and best suit the requirement of the present invention to provide a container for the fire extinguishing material. Of course, alternative materials for construction of the bag may be selected by the man skilled in the art without need for further inventive thought.

Once the bag 12 has been filled with fire extinguishing material the control valve of the fire extinguisher head 3 is shut off and the void of the chamber 2 surrounding the bag 12 within the body 1 of the fire extinguisher is filled with the nitrogen, dry air or other gas through the tank valve 11 and associated pressurisation passageway.

Thereafter, when it is desired to operate the fire extinguisher by means of the trigger handle 9 the contents of the bag 12 will be expelled by the gas pressure surrounding the bag 12 and it has been found that substantially the entire contents of the fire extinguisher may thus be used in contrast to the conventional design of fire extinguisher, using a siphon tube, which generally leaves a substantial residual volume of fire extinguishing material that the extension of the tube 7 cannot reach or which then ceases to be pressurised through loss of the pressurised gas from the outlet nozzle 8.

It will therefore be appreciated that the present invention provides a number of significant advantages over the prior art and represents a substantial advance forward in the design of portable fire extinguishers which are liquid based, i.e dispense fire extinguishing materials that are stored within the fire extinguisher in liquid state.

Although described above with respect to one preferred embodiment, the skilled practitioner will appreciate that numerous alternative embodiments are conceivable within the scope of the invention.

Claims

CLAIMS:

1. A portable fire extinguisher of the type which dispenses a liquid-based fire extinguishing material, the extinguisher being characterised in that the fire extinguishing material is accommodated within the body of the fire extinguisher inside a collapsible vessel within the body of the fire extinguisher and in that the contents of the vessel are pressurised to be expelled by the fire extinguisher, in use, by pressurisation of the chamber within the fire extinguisher body surrounding the exterior of the vessel.

2. A portable fire extinguisher as claimed in Claim 1, wherein the collapsible vessel is a bag.

3. A portable fire extinguisher as claimed in Claim 2, wherein the bag is a plastics bag.

4. A portable fire extinguisher as claimed in Claim 3 wherein the plastics bag is composed of a laminate of plastics and aluminium

5. A portable fire extinguisher as claimed in any preceding Claim, wherein the vessel is adapted to be releasably secured in a gas and liquid tight fashion to the feed or siphon tube of the head of the fire extinguisher.

6. A method of filling a portable fire extinguisher which comprises providing a portable fire extinguisher claimed in any preceding Claim; charging the fire extinguisher with fire extinguishing material through the outlet nozzle of the fire extinguisher and thence through the delivery tube of the fire extinguisher head into the vessel; and then supplying a pressurising gas through a pressurisation port in the body or head of the fire extinguisher into the void between the vessel and the internal wall of the chamber of the fire extinguisher body to place pressure on the outside of the vessel and thereby pressurise the contents thereof.

7. A portable fire extinguisher substantially as hereinbefore described with reference to the accompanying drawing.