Hitherto, the most commonly used such fire-fighting medium is water, although various foams have also been used, as well as gases, such as carbon dioxide and halon.

Many attempts have been made to improve the fire- fighting efficiency of water. Additives have been put into the water to this end, but the improvement in the fire-fighting efficiency of the water does not amount to more than a fraction. Foams seek to put out fires by starving the combustible materials of oxygen, but these are not so effective in removing heat from the materials that were blazing which therefore remains dangerous. for a long time even after the fire has been extinguished.

Gaseous materials which also have the effect of starving combustible substances of oxygen are very effective at extinguishing flames and preventing the spread of fire, but again they are not very effective in removing the heat from the substances which were on fire, and in enclosed areas, such as in the lower decks of ships, especially war ships,. they are lethal to any personnel within the fire area.

The present invention seeks to obviate these disadvantages.

Accordingly, the present invention is directed to

apparatus for and a method of fighting fire as set out in the opening paragraph of the present specification in which the pumpable fire-fighting medium comprises ice, preferably within water.

Such material is already known in the fields of air- conditioning and food preservation and in the electronic fields. In one form, it is referred to by the registered Community trade mark BINARY ICE of INTEGRAL Energietechnik GmbH. It may also be referred to as pumpable ice, liquid ice, or ice slurry.

Fire-fighting apparatus made in accordance with the present invention may comprise a fire-fighting appliance containing ice within water as its pumpable fire-fighting medium. This medium may be contained in a tank of the appliance. Although such an ice-water mix can remain in its binary state for many hours even without the tank being especially thermally insulated, it is preferable for the tank to be thermally insulated in some way. For example, it may have a double skin, the space between the double skin may be a vacuum, one or other of the walls may be silvered or otherwise reflective to thermal radiation, and/or the tank may simply be lagged by an insulating material, such as a glass fibre wool, as is used for loft insulation, for example. Many other thermally insulating materials could be used in the form of a jacket around the tank.

A separate tank may be used to create, store or maintain ice within water, such as to be readily

transferable to a fire-fighting appliance.

Alternatively, the fire-fighting appliance tank may be connected in quick release manner to a main tank in which the pumpable ice-water mix in which the ice is retained as ice particles within the water, can be created, stored and maintained, so that there is a continuous transfer of this fire-fighting medium between the two tanks. As a result, as soon as the fire-fighting appliance is required to fight fire, it can be readily disconnected from the main tank, the fire-fighting medium within the appliance having been maintained in its cool state right up to the time it is required.

The fire-fighting appliance may have an ice maker, which may operate by means of a vapour compression cycle, or which may use a vacuum system, in combination with a tank to create, store and maintain such an ice/water mixture.

Another form of fire-fighting apparatus embodying the present invention may comprise an ice maker which can be connected to a source of water, such as a fire hydrant, the ice maker being sufficient to create such an ice/water mixture from the water of the water source.

The fire-fighting apparatus may be installed on a ship. It may have a number of outlets in different cabins and cavities within the ship to enable any part of it to be supplied with ice/water mix.

In another embodiment of the present invention, the fire-fighting apparatus is installed within or adjacent

to a building, or within or adjacent to industrial plant, and may be connected to a fire-fighting sprinkler to deliver such ice/water mixture to any room or other part of the building, or any part of such plant.

The fire-fighting apparatus may comprise at least two pumps both arranged to urge ice/water mixture to at least one fire-fighting sprinkler, and a valve arranged downstream of the sprinkler, in which the valve opens at a predetermined pressure which is greater than that which one of the pump is capable of delivering, but less than the pressure which the other pump is capable of delivering.

It is preferable for the water from which the ice/water mixture is created to have a freezing point depressant, such as ethylene glycol or a salt (especially sodium chloride).

To this end, means may be provided in any of the foregoing embodiments of the present invention to add salt to the water which is used for the ice/water mix.

Clearly, in the case of a ship which has fire- fighting equipment on board, it may take in seawater which already contains salt, and pump this through an ice maker to create ice particles within the water.

Preferably, the percentage of ice to water by weight is above 20%, preferably above 40%. However, any percentage of ice will assist.

Preferably, the ice in the water comprises particles of no greater than 0. 5cm in average diameter, and is

preferably substantially less than 1mm in average diameter and, even more preferably, less than 0. 1mm average diameter, although it is conceivable that many particles of the ice may form clusters, the aggregate size of which is greater.

Examples of apparatus embodying the present invention may be described with reference to Figures 1 to 4 in which each Figure shows diagrammatically generally elevational views of respective embodiments of the present invention.

The embodiments of the present invention shown in Figure 1 comprises fire-fighting equipment that may be mounted on a vehicle, such as a fire engine or on a trailer or it may be a static system for use in a building or industrial plant.

The apparatus comprises a thermally insulated tank 10 provided with a salable aperture 12 through which it may be filled with an ice/water mix 13 in which ice particles are present in the water. There is also provided a standard connection indicated diagrammatically at 14 by which such an ice/water mixture can be fed into the tank using standard pipe and connector means. A drain 15 at the bottom of the tank 10 enables its contents to be drained. A pump 16 has an input connected to the bottom of the interior of a tank 10 via a line 18, and an output connected to an ice maker 20, the output of which returns to the interior of the tank 10 via a line 22 at a higher position than that from which the line 18

draws ice/water mixture from the interior of the tank 10.

Control means may be provided to ensure that the ice maker 20 is switched off once the ice/water ratio exceeds a predetermined value as detected by a sensor 23 in the ice maker 20, and switched on when it falls below a predetermined value, as also detected by the sensor 23.

Even when the ice maker 20 is switched off, the pump 16 continues to operate, either continuously or intermittently, both to stir the container contents and to continue to monitor its temperature.

The apparatus is further provided with a fire pump 24 having its inlet connected to receive ice/water mix from the interior of the tank 10 via a line 26, and has its output connected to a nozzle 28 via a hose 30.

Whilst the fire-fighting apparatus remains in a dormant condition, the ice/water mix in the tank 10 will be continually or intermittently monitored to ensure that its ice content does not fall below a predetermined value. When it does, the control means ensures that the pump 16 is operating to pump the ice/water mix through the ice maker 20, and also switches on the latter, to create a higher percentage of ice with the ice/water mix of the contents of the tank 10.

It will be appreciated that the tank 10 may be filled with water containing salt to assist in the manufacture of. the ice/water mix, in which case the pump 16 and the ice maker 20 are used to create the ice/water

mix, as well as to maintain it in a satisfactory condition. The addition of the salt may be from a source 31 connected to the inlet 32 for feeding salt to the interior of the tank 10. Such feed means may be provided in each and every further illustrated embodiment of the present invention.

When the apparatus shown in Figure 1 is used for fire-fighting, the pump 24 is switched on to draw the ice/water mix from the tank 10 and pump it out through the hose 30 and the nozzle 28 which may be trained on a fire, or on the air surrounding the fire to cool that surrounding air, as in conventional fire-fighting techniques. However, it is found that with the use of an ice/water mix as the pumpable fire-fighting medium, it may render the apparatus three times as effective, or more than three times as effective as corresponding equipment which uses simply water as the fire-fighting medium, and even more effective at cooling the air around a fire.

In Figures 2 to 4, components which correspond to those shown in Figure 1 have been given the same reference numerals.

In the embodiment of the invention shown in Figure 2, the tank 10 is larger, in this case by virtue of its increased height, so that it is in the form of a tower, and an intermediate tank 32 is connected between the main tank 10 and the fire pump 24. This connection is effected by means of a transfer pump 33 having its inlet

connected to a lower region of the interior of the tank 10 and an output connected via a line 36 to an inlet 38 to the interior of the tank 32 positioned at the top thereof. A further line 39 connects the bottoms of the interiors of the tanks 10 and 32. The interior of each tank is also provided with a stirrer 40 rotated by a motor 42, to stir the contents of each tank.

There may be a multiplicity of tanks 32 connected to the main tank 10, each tank 32 having its own fire pump 24, nozzle 28 and hose 30. For example, a tank 10 may be installed in a fire station, and each of the tanks 32 may be installed on mobile fire-fighting appliances. In that case, it is desirable for the connections between the tanks 10 and 32 to be made in a quick release fashion.

In the embodiment shown in Figure 3, the nozzle 28 and hose 30 of the Figure 1 embodiment are replaced by a fire-fighting sprinkler system 44 in a building or industrial plant having a multiplicity of sprinklers 46 connected along a line 48 from the output of the fire pump 24. A pressurising pump 50 ensures that the sprinkler system is maintained at an adequate pressure.

It is connected to operate when the pressure in the line 48 as determined by a pressure sensor 51 therein, in this embodiment located downstream of the sprinklers 46, is below a predetermined level. A check valve 52 between the sensor 51. and the interior of the tank 10 remains closed, its forward opening pressure being greater than that delivered by the pressurising pump 50. This ensures

no loss of head through the return line 48 whilst the system remains dormant. A further check valve 54 located immediately downstream of the pump 50 inhibits any return flow of fluid in the line 48, to maintain the pressure therein. A further check valve 56 located immediately downstream of the fire pump 24 also inhibits any return flow of fluid in the line 48, in this case back through the pump 24 and the line 26.

In the event of a fire causing one or more sprinkler heads 46 to open, the pressure sensed by the sensor 51 will fall below the already referred to predetermined level, to cause the pump 50 to operate. However, this is insufficient to restore the pressure to the already referred to predetermined level. On the contrary, the pressure level on the line 48 will continue to fall to a second predetermined threshold level, whereupon the fire pump 24 will operate. It will be understood control circuitry (not shown) effects this operation. In the event that only a few sprinklers 46 are opened, the pressure delivered by the pump 24 is sufficient to open the check valve 52, and ensure even in such circumstances a rapid delivery of the contents of the tank 10 to the sprinklers which are open.

In the embodiment of the present invention shown in Figure 4, a fire pump 60 has its inlet connected to a port 62 for the intake of water. The output from the pump 60 is connected to an inlet of an ice maker 64 which has an outlet connected to a nozzle 66 via a flow

detector 68. When in use, the equipment shown in Figure 4 has its pump 60 switched on. The flow detector 68 is connected to switch on the ice maker 64. This creates an ice/water mix on demand.

The Figure 4 embodiment may be installed on board a ship (not shown) in which case the port 62 may be arranged below sea level, and the fire pump 60 may be a marine pump.

Alternatively, the Figure 4 embodiment may be for example installed on a mobile fire-fighting appliance, in which case the port 62 may be adapted for connection to a fire hydrant, and also to a source of freezing-point depressant (not shown). In one modified form of such equipment, at least the ice-maker 64 and the flow detector 68 may be provided on an auxiliary appliance, the other illustrated parts being provided by at least one conventional appliance. A by-pass (not shown) may be provided to pass fluid through the ice-maker 64 in the event that the nozzle 66 is shut, to prevent the latter becoming blocked. by ice.

Numerous variations and modifications to the illustrated apparatus may occur to the reader without taking the resulting construction outside the scope of the present invention. To give one example, the fire- fighting pump 60 and the ice maker 64 arrangement, shown in Figure 4, can be connected directly to the sprinkler system 44, shown in Figure 3, without the intermediary tank 10 provided a supply of water and preferably also

salt is available. The ice/water mix may contain additives to make it foam when it exits the nozzle 28.

It will be appreciated that the ice in the ice/water mix considerably enhances its cooling effect.

Freezing point depressants other than salt or ethylene glycol may be used, such as seawater, sugar, propylene glycol, methanol, ethanol, or Talin (Registered Trade Mark), or any mixture of any of the proposed freezing point depressants.

The illustrated apparatus may be adapted so that once the ice/water mixture is discharged from the tank or tanks, the fire pump 24 can be readily connected to pump water for example from a hydrant, in a conventional manner.

There may be more than one fire pump 24, especially in the apparatus illustrated in Figure 3, in which case such pumps may be staged as in conventional sprinkler systems.