GB2144037A - Method of and apparatus for foam production - Google Patents

Abstract

In a method of foam production for use in fire fighting, a fire tender is used which has a water supply channel in which a pump impeller is located. Foam is produced by introducing a foaming agent into a flow of water in the water supply channel upstream of the pump impeller. Apparatus for producing the foam comprises jets (10, 11) which are located in the water supply channel (4) upstream of a pump impeller (1). The channel (4) is connected to a channel (5) which leads to a water tank mounted on a fire tender and in which a shut-off valve (6) is located and the channel (4) can also be connected to an external water supply by a port which is normally closed by a blanking cap (7). The jets (10, 11) are connected to a tank containing foaming agent by lines (14, 15 and 16), one line (14) leading from the tank to a valve (17) and the other lines (15, 16) leading from the valve to the jets (10, 11). The valve is arranged to control the supply of foaming agent to the jets so that both jets are supplied, or one or the other is supplied or neither of the jets is supplied with foaming agent. <IMAGE>

Description

SPECIFICATION Method of and apparatus for foam production This invention relates to a method of and an apparatus for foam production.

In the field of fire fighting, many types of fire can be usefully contained or extinguished using a layer of foam which smothers the fire by preventing oxygen from reaching it.

However, there are serious economic problems attached to foam generation by the usual methods, particularly when using front line fire fighting vehicles.

The present invention therefore seeks to provide a method of and apparatus for foam production which is economically advantageous. According to a first aspect of the invention there is provided a method of foam production which comprises supplying a foaming agent to the water supply channel of a fire tender upstream of the pump impeller.

According to a second aspect of the invention, there is provided an apparatus for foam production comprising means for supplying a foaming agent to the water supply channel of a fire tender upstream of the pump impeller.

Preferably the foaming agent is supplied by means of a jet which penetrates the water channel. The part of the water channel used for this purpose may be in the interior of the pump housing, in which case the jet extends into the housing, or the jet may be provided in the line connection between the water supply and the pump.

The jet is preferably angled to provide a jet of foaming agent into the water flow generally in the same direction as the water flow. The jet orifice may be arranged to present an acute angle to the flow direction, preferably of the order of 45 .

Suitably the foaming agent may be stored in a tank above the orifice so that a head pressure is produced. In one example, with an orifice of the order of 2.5 mm, it has been found that a head of about 1 metre is sufficient.

The foaming agent may be Petroseal, and this may be used in a 3% mix with water.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Figure 1 is a diagram of the inlet of a water pump showing the installation of a jet or jets in the water channel; Figure 2 is a side view of a jet for single jet application; and Figure 3 is a side view of a jet for a twin jet application.

Figure 1 shows diagrammatically the inlet side of a UMP Godiva Pump. Thus there is shown the pump impeller 1 in its impeller chamber 2. The input channel to the impeller chamber 2 is indicated at 3 and has two possible supply sources. As shown, the pump is connected via channels 4 and 5 and a shut off valve 6 to the water tank (not shown) of the fire tender. The other possible supply source, usually blanked off with a blanking cap 7, enables connection of the pump to external water supplies. Because these sources may not be clean, a strainer 8 is provided. The means for supplying a foaming agent into this apparatus comprises two input jets 10 and 11 mounted on the wall of the channel 3 and arranged to admit jet foaming agent into the water flow in the flow direction of the water.The jets 10 and 11 are connected to a three position valve 12, the valve having an inlet 14 from a container of foaming agent (not shown) and two outlets 1 5 and 1 6 for the jets 10 and 11 respectively. The valve control 1 7 provides for cutting off the supply or connecting the supply to one cr both of the jets 10 and 11.

In operation of the apparatus, the water supply is connected by opening the shut off valve 6 and the foaming agent is supplied by operation of the valve 1 2. Whether one or two jets is used will depend on a nummber of parameters e.g. the head of the foaming agent supply, the nature of the foaming agent, the water flow rate etc. Then the pump is started and, using a fog gun on the end of the hose, a foam will be sprayed out.

Two types of jet nozzle are shown in Figures 2 and 3.

A jet intended for single jet operation can be seen in Figure 2. This jet comprises a copper tube 20 which is angled at one end, the angled portion 21 being provided with a generally closed end 22, lying at a transverse angle to the axis of the pipe portion 21. The end 21 is provided with a jet aperture 23.

With a 5/8" (15.75 mm) outside diameter copper tube, the aperture 23 may suitably be 7/64" (2.5 mm). The other end of the pipe 20 is brazed at 24 to a MacDonald coupling 25.

A jet intended as one jet of a twin jet operation (Figure 3) comprises a 3/8" (9.45 mm) brass pipe 30 threaded at both ends at 31 and 32. A jet nozzle element 33 is screwed onto the thread 31 and comprises a block 34 having a threaded aperture 35 to receive the pipe 30 and, at right angles thereto, a jet passage 36, suitably of 1 /8" (3.17 mm) diameter. The end 38 of the block lies at a transverse angle to the axis of the jet passage.

The other end 32 is secured into a mounting element 37 (Fig. 1). A brass hexagon 39 is soldered onto the brass pipe 30 to enable it to be gripped by a spanner for tightening it in the mounting element.

It will of course be appreciated that the measurements given here are only examples.

Other dimensions may be used as desired and depending on circumstances.

In practical tests it was found that using a head of 1 metre for the foaming agent supply, and using Petroseal as the foaming agent, a 3% mix of the Petroseal produced a satisfactory foam. The angle of the end of the jet used was of the order of 45 .

It will be understood that various modifications or additions may be made to the above described embodiments, without departing from the scope of the invention. For example, many of the dimensions may be varied depending on the circumstances which may be present.

This may depend on the foaming agent used, the flow rate of the water and the type of foam required etc. While the jets have been shown extending into the casing of the pump itself, the jets may be positioned otherwise, e.c. in the feed line to the pump. The materials used for the jet construction may vary as may the actual construction. While the use of one or two jets has been described, more than two jets may be provided if desired.

Alternatively a single jet head could be provided with multiple jet orifices.

Claims (22)

1. A method of foam production for use in fire fighting in which a fire tender is used provided with a water supply channel and a pump impeller located in said channel, wherein a foaming agent is supplied to the water supply channel upstream of the pump impeller.

2. A method according to claim 1, wherein the foaming agent is supplied to the water supply channel in the form of a jet which is directed into a flow of water through said channel generally in the same direction as the water flow.

3. A method according to claim 2, wherein the jet has an orifice which is arranged to present an acute angle to the direction of water flow.

4. A method according to claim 3, wherein said acute angle is approximately 45 .

5. A method according to any preceding claim, wherein the foaming agent is Petroseal.

6. A method according to claim 5, wherein the foaming agent is added to the water supply channel in an amount of about 3%.

7. A method of foam production substantially as described herein with reference to the drawings.

8. Apparatus for foam production for use in fire fighting comprising means for supplying a foaming agent to a water supply channel which is adapted to be installed in a fire tender, a pump impeller being located in said water supply channel and the supply means being arranged to supply said foaming agent to the water supply channel upstream of the pump impeller.

9. Apparatus according to claim 8, wherein the foaming agent supply means includes a jet which extends into the water supply channel.

10. Apparatus according to claim 9, wherein the pump impeller is contained within a pump housing which contains part of said water supply channel and wherein the jet extends into the pump housing.

11. Apparatus according to claim 9, wherein the water supply channel takes the form of a line connecting a water supply to the pump and wherein the jet is provided in said line.

1 2. Apparatus according to any one of claims 9 to 11, wherein the foaming agent is contained in a tank located above the level of the jet to provide a head of pressure.

1 3. Apparatus according to claim 12, wherein the tank is connected to the jet by a fluid line and wherein a valve is provided in said fluid line to control the supply of foaming agent to the jet.

14. Apparatus according to any one of claims 9 to 13, wherein a further jet is provided for supplying foaming agent to the water supply channel, said further jet being located adjacent to the firstmentioned jet.

1 5. Apparatus according to claims 1 3 and 14, wherein the further jet is connected to the valve by a further fluid line.

1 6. Apparatus according to claim 1 5 wherein the valve is provided with control means enabling the supply of foaming agent to both jets to be shut off or permitting the supply of foaming agent only to the firstmentioned jet or only to the said further jet or to both jets simultaneously.

1 7. Apparatus according to any one of claims 9 to 16, wherein the or each jet is angled to provide a or a respective stream of foaming agent into a flow of water through the channel in the general direction of said water flow.

1 8. Apparatus according to claim 17, wherein the or each jet is provided with an orifice which is arranged to present an acute angle to the direction of water flow.

1 9. Apparatus according to claim 18, wherein said acute angle is approximately 45".

20. Apparatus according to any one of claims 8 to 19, wherein the foaming agent is Petroseal.

21. Apparatus according to claim 21, wherein the supply means is arranged to supply the foaming agent to the water supply channel to produce a mixture containing 3% of foaming agent.

22. Apparatus for foam production substantially as described herein with reference to the drawings.