A nozzle head for a fire extinguisher

The invention relates to a nozzle head for a fire extinguisher of that kind which comprises a source of liquid and a hose and/or a pipe for connecting the source of liquid to a liquid inlet of the nozzle head, whereby the nozzle head comprises a cylinder, a rearmost end cover with the liquid inlet and a foremost end cover with a number of atomising nozzles connected with the liquid inlet via a liquid channel for during operation ejecting atomised liquid against a fire to be extinguished.

It is a well-known fact that water in its plain state is not a very effective means for extinguishing a fire as up to 98% of the water will not take part in the extinguishing but in stead slide of the burning objects without ever reaching the primary combustion. If fire has broken out in particularly flammable liquids, such as gasoline, spraying with plain water can on the contrary result in a spreading of the fire.

The water is better utilised when it is carried in the shape of small drops. However, an optimum utilisation is only obtained with finely atomised water, which has a very large total surface and evaporates immediately when it is sprayed into areas where combustion is taking place at high temperatures.

The last-mentioned effect is extremely desirable as the smoke gases from the fire are cooled momentarily just as the violent vapour formation also displaces the combustible gases and reduces the oxygen content of the air.

During a fire, air will flow to the primary combustion zone where the oxygen content of the air will feed the combustion. However, the fine water drops are so small and have a mass so small that they will tend to drift in the air and by this be taken into the combustion zone where the combustion thereby is impeded or stopped altogether.

Finely atomised water will also be able to penetrate fibrous material and thereby advantageously be able to reduce its combustibility while small drops merely will remain on the surface of the material.

In a cloud of finely atomised water, the drops will furthermore be so small and have a mutual distance so large that the electric conductivity of the cloud will be very small. Finely atomised water can therefore be utilised with minimal risk for the operator even if there are live wires at the scene of the fire .

Conventionally, pressures as high as between 150 and 250 bar have been utilised in order to atomise water finely enough for the fighting of a fire. However, the high pressures require heavy equipment which normally only can be established in stationary and/or large units.

It is of crucial importance that the extinguishing of a fire is started as soon as possible. It is however normally difficult quickly to arrive at the scene of the fire with such heavy equipment especially in heavy traffic in for example a city.

The formed finely atomised water has in itself furthermore turned out to have a range too short to be able adequately to prevent the fire fighters being injured by the heat emitted by the fire.

For quickly and effectively extinguishing of fluid fires (class B fire) and securing against re-ignition, it can be necessary to utilise foam which forms a stable carpet of small bubbles for effectively cooling and smothering fires that are difficult to control in any other way.

At fire turnouts, it will not always immediately be clear if the fire in question is a class A, B, C, or E fire. This means that it, at the time of the turnout, can be uncertain whether it is one type of fire-extinguishing equipment or the other that would

be most effective in the given situation, and that therefore should be brought along. It is therefore an advantage if both finely atomised water and foam can be discharged from the same fire-extinguishing device so that the choice between foam or finely atomised water as fire-extinguishing means only need being made when the fire brigade has arrived at the scene of the fire .

In firefighting, fires are organized into several fire classes that describe what kind of fuel or heat source it has, and by extension what methods will be necessary to contain it or put it out .

In the present application the standard European classes, EN3- 7+Al of 26. September 2007 is used, but in the table below both the European/Australasian and American classifications are listed including the relationship between the two sets of classes .

American European/Australasian Fuel/Heat source

Class A Class A Ordinary combustibles

Class B Flammable liquids

Class B

Class C Flammable gases

Class C Class E Electrical equipment

Class D Class D Combustible metals

Class K Class F Cooking oil or fat

It is furthermore an advantage if the quantity of fire- extinguishing means necessary for extinguishing a fire is as small as possible so that the fire-extinguishing device is not restricted to stationary use but can also be utilised offensively .

A combined fire-extinguishing device is among others disclosed in US Patent 2,832,424. This device can, with a valve, be converted to discharge either atomised water or foam but from the same nozzle type. A nozzle for foam can however not be

utilised for finely atomising of water. The drops in the atomised water, which the conventional fire-extinguishing device is able to discharge, will therefore be too coarse to optimally be able to fight a fire.

From WO 94/06517 is known another fire-extinguishing device having a single liquid conduit. Said device can only use liquid for extinguishing a fire and not foam. The liquid conduit has a first branch connected to a nozzle for delivery of a concentrated water jet and a second branch connected to a nozzle head for delivery of the liquid in atomised form. The liquid is forced into helically rotation along a helical spring for atomising the liquid. In order to effectively protect the operator from the heat exposure from the fire a very high pressure of about 300 bars must be used. Furthermore, this design is heavy and expensive to manufacture.

US Patent 4,420,047 discloses a similar fire-extinguishing device for fitting in aircraft. The device can selectively discharge either foam or atomised water but also in this case, from the same nozzle type. This device is not able to fight a fire by means of finely atomised water either.

The applicants WO publication 99/32194, which is incorporated in the present patent application by reference, discloses a fire- extinguishing device comprising at least one liquid conduit connected at one end to a source with a fire extinguishing liquid under pressure, and at the other end with channels in a nozzle head with a number of nozzles. The channels of the nozzle head comprise a first channel connected to at least one atomising nozzle for discharging liquid in atomised form, and a second channel, which has an air intake, and downstream of this is connected to a foam nozzle for discharging a liquid in foamed form. The device can be utilised for effectively extinguishing class A, B, C, and E fires and can with one single handle be converted to fighting fires with either foam or water. The water can be atomised to a very high fineness by means of a relatively slight pressure of about 10 - 25 bars, and a range of over 10

metres is obtained. Far less water is used for extinguishing a fire than when using conventional fire extinguishing equipment.

Excellent results are achieved by means of this known fire- extinguishing device for fighting fire. Some of the energy imparted to the atomised liquid ejected from the atomising nozzles is however used for carrying along air fetched from the surroundings of the foremost end face of the nozzle head. That implies that the spreading and the range of the atomised liquid are restrained and that the effect of the fire fighting thereby is reduced.

The above-mentioned disadvantages of the prior art nozzle heads for fire extinguishers are according to the present invention remedied by,

in a first aspect of the invention providing a nozzle head of the kind mentioned in the opening paragraph that is able to finely atomise liquid by means of a relatively slight pressure of about 10 - 25 bar and discharge the finely atomised liquid over a longer range than hitherto known,

in a second aspect of the invention providing a nozzle head of the kind mentioned in the opening paragraph by means of which, fires in European classes A, B, C, E, D and F optimally can be fought,

in a third aspect of the invention providing a nozzle head of the kind mentioned in the opening paragraph that easily can be converted to fighting fires with foam and/or liquid,

in a fourth aspect of the invention providing a nozzle head of the kind mentioned in the opening paragraph by means of which a heavy jet of liquid can be ejected against a fire,

in a fifth aspect of the invention providing a nozzle head of the kind mentioned in the opening paragraph by means of which a

carpet of atomised liquid can be ejected against a fire to be extinguished,

in a sixth aspect of the invention providing a nozzle head of the kind mentioned in the opening paragraph which is formed in such way that atomised liquid and/or foam can be ejected against a fire behind an object,

in a seventh aspect of the invention providing a nozzle head of the kind mentioned in the opening paragraph which is equipped with ejection nozzles adapted to atomise the liquid for extinguishing a fire so fine that the electrically conductivity of the cloud of atomised liquid is so low that the fire extinguishing safely can take place even in areas with live wires .

The effect of the fire fighting can according to the invention advantageously be improved by making the outer face of the foremost end cover of the nozzle head streamlined so that the spreading and the range of the atomised liquid is extended since less energy now is used for carrying along air fetched from the surroundings of the foremost end face of the nozzle head.

A brilliant outer face of the foremost end cover of the nozzle head can according to the invention be achieved by dividing said face up into alternating grooves and ridges and forming the mouths of the atomising nozzles in the ridges and the grooves with a slope into the injection direction. Air from the surroundings can by means of this construction now be carried along with the atomised liquid without or with only a little loss of energy.

The nozzle head can according to the invention have a foam nozzle for ejecting foam separately or simultaneously with atomised liquid.

By according to the invention placing the foam nozzle at or near the centre of the nozzle head is advantageously obtained that

foam and atomised water can be discharged along the same axis so that the operator easily can change between using the atomising nozzles and/or the foam nozzle without directly having to alter the axial orientation of the nozzle head.

The foam nozzle can in an expedient embodiment according to the invention be formed as a pipe stub extending from the foremost end cover of the nozzle head, and the end face of the pipe stub can be serrated such that pipe stub is able to penetrate obstacles like glass when using the nozzle head as a hammer.

Sometimes it is not possible in a sufficient degree to penetrate the fireplace with atomised water or foam. According to the invention the nozzle head in such cases can be detachable mounted with a tube for ejecting a heavy jet of water able to arrive at the primary combustion.

The nozzle head can in another expedient embodiment according to the invention have a bended shape allowing the operator to fight a fire placed behind an object without risk for being harmed by the heat from the fire.

The invention will be explained in greater detail below, describing preferred embodiments by way of example with reference to the drawing, in which

Fig. 1 is an axial sectional view of a nozzle head according to the invention for a fire extinguisher,

Fig. 2 shows the same seen from the foremost end of the nozzle head,

Fig. 3 is an axial sectional view of a tube for detachable being mounted in the nozzle head shown in fig. 1,

Fig. 4 shows the nozzle head shown in fig. 1 detachable mounted with the tube shown in fig. 3,

Fig. 5 shows the same seen from the foremost end of the nozzle head, and

Fig. 6 shows another embodiment of a nozzle head according to the invention with a bended shape,

Liquid means in the following water. The water may be added a foaming agent for by means of air foaming the water.

Fig. 1 - 2 show a nozzle head 1 according to the invention built up of a cylinder 2 with a rearmost end cover 3 and a foremost end cover 4. The rearmost end cover is in this case screwed onto the cylinder by means of a screw joint 5 and the foremost end cover by means of a screw joint 6.

Seven atomising nozzles 7 are formed in the foremost end cover. The atomising nozzles are, as seen in fig. 2, placed in a row along a circle. The mouths 8 of the atomising nozzles are placed in the outer face 9 of the foremost end cover 4.

By means of this arrangement it is possible to eject a quantity of water sufficiently large for fighting a fire at the same time as a very fine atomisation of the water is achieved.

The arrangement of the atomising nozzles is known technique, which in details is described in the applicants WO publication 99/32194. They therefore will not be discussed further here.

Fig. 1 and 2 also shows that a foam nozzle in form of a pipe stud 10 is placed in between the atomising nozzles 7. The end face 11 of the pipe stub is serrated. The pipe stub can, if occasion should arise, penetrate obstacles (not seen) like e.g. glass when using the nozzle head as a hammer. The pipe stud is equipped also with an inner thread 12, the purpose of which will be explained later on in the description.

Known technique is also the arrangement of the inlet 13 in the rearmost end cover 3 for leading water which has been added a

foaming agent to the nozzle head in which it is foamed by admission of air. This technique is likewise in details described in the applicants WO publication 99/32194 and will therefore not be discussed further here.

The foam produced in the cylinder is guided to the nozzle head via a foam channel 14 and the atomising water is guided to the atomising nozzles via a water channel 15 connected to an inlet 16 for the atomising water.

The inlet 13 for the foaming water is via a hose and/ore a tube

(not shown) connected to a source of foaming water (not seen) and the inlet 16 for the atomising water is via a hose and/ore a tube (not shown) connected to a source of atomising water (not seen) .

Means for activating the ejecting of atomised water and/or foam is provided too.

Some of the air around at least the foremost end part of a nozzle head for fighting a fire will automatically be carried along with the atomised water ejected against the fire.

Accelerating the air and keeping it moving is using some of the energy imparted to the water during the ejection process with that disadvantageous effect that the rate of motion and thereby the reach of the atomised water is reduced.

High rate of motion and long reach of the atomised water is however required for optimally being able to fight a fire.

The loss of energy for by means of the atomised water carrying along air from the surroundings of the nozzle head is depending on the shape of the nozzle head. Making the shape of especial the foremost part of the nozzle head streamlined so that the air is allowed to flow with little air resistance can however reduce the loss.

A minimum of air resistance and thereby of loss of energy is obtained by means of the shape of the outer face of the foremost end cover of the nozzle head according to the invention.

This shape is seen in fig. 1 and 2 showing that the outer face 9 of the foremost end cover 4 of the nozzle head 1 is divided up into alternating grooves 17 and ridges 18 and that the mouths 8 of the atomising nozzles 7 are placed on the ridges.

The ridges 17 are arranged in a circular row with grooves 16 of equal width between each of two ridges for thereby achieving a uniform flow of air and of the ejected atomised water.

The mouths 8 of the atomising nozzles 7 are moreover placed on top of the ridges where the mouths in the main are surrounded of the grooves only. The ejected atomised water therefore in the main can draw air from the surroundings of the foremost end cover of the nozzle head via the grooves between the ridges only .

Said grooves are extending mainly radially inwards from the periphery of the foremost end cover with a width, which is increasing into the ejection direction of the liquid. The grooves moreover are sloping into the ejection direction of the liquid.

The distance air needs to flow in the grooves for arriving to the mouths of the atomising nozzles is extremely short in relation to the distance the air needs to flow when using known technique and this fact implies together with the above described shape and orientation of the grooves that air flow, if any to the mouths of the atomising nozzles is resisted very little when passing the grooves.

Consequently the loss of energy is reduced substantially whereby the range of the ejected atomised water is extended in relation to the known technique while the fan of the atomised water simultaneously is widened. A fire now can be fought optimally by

using the nozzle head according to the invention with a pressure for atomising the water as low as ten bar.

The above-described arrangement of the outer face of the foremost end cover of the nozzle head is resulting also in that the water is ejected in a homogenous fan of extremely fine particles since the free spreading of the ejected atomised water is only minimally obstructed by air flowing from the surroundings of the end part of the nozzle head.

The fan is in the nature of a mist with so low electrical conductivity that the nozzle head according to the invention can be used for fighting a fire on a place where there are current carrying electrical wires with poor or none insulating.

In practise is has turned out that fires can be fought with a nozzle head according to the invention even if there are electrical wires with poor or none insulating carrying current with voltages up to 20.000 Volt on the fireplace. Thus, using the nozzle head according to the invention, it is to fight fires in high tensions areas.

The surroundings of a fireplace and/or the fireplace itself can sometimes be of such kind that it cannot be penetrated at least sufficiently of either atomised water or foam whereby the fire- extinguishing operation risks to fail.

This problem can, according to the invention, be remedied by ejecting a heavy jet of liquid against the fire by means of a nozzle tube 19, which detachable is mounted in the foam channel of the nozzle head and is connected to the source of atomising water or to another source of water via a hose and/or a pipe

(not seen) .

This nozzle tube 19 is seen in fig. 3. The nozzle tube has in one end a relatively large nozzle 20 and an outer thread 21 and at the opposite end a tightening ring 22.

The nozzle tube 19 has in fig. 4 and 5 been mounted in the foam channel 14 of the nozzle head 2 by screwing the outer thread 21 of the nozzle tube into the inner thread 12 of the pipe stud 10 of the nozzle head and tightening the tube in the inlet 13 of the nozzle head by means of the tightening ring 22.

Inserting of the nozzle tube for ejecting a heavy jet against a fire which is difficult to penetrate with atomised water or foam into the foam channel 14 of the nozzle head can in the way described above be done easily and quickly and the tube can likewise easily and quickly be removed when needing the nozzle head for ejecting foam again.

The mouths of the atomising nozzles are in an expedient embodiment of the invention flat and parallel (not shown) whereby is ejected a flat fan of atomised water that like a carpet can cover a fire to be extinguished.

Fig. 6 shows an embodiment of the nozzle head, which corresponds to the nozzle head shown in fig. 1 and 2. Same numerals therefore are used for same parts.

The nozzle head is however in this case bended whereby advantageously is obtained that the operator can fight fires behind or below objects like e.g. doors or furniture without risking to be harmed of the heat from the fire.

Fig. 6 shows an embodiment of a nozzle head, which is bent a sharp angle of, in this case, 90°. The bend can however, within the scope of the invention, be curved and the bent angel be of any suitable size.

The nozzle head according to the invention can with advantage be used as a nozzle head for the fire extinguisher disclosed in the applicants WO publication 99/32194 instead of the nozzle head disclosed in this document.

In said document also is disclosed a pressure bottle with pressure gas for keeping the water to be atomised under pressure. Instead can, according to the invention, be used a pump for pumping water under pressure to the nozzle head.

The nozzle head of the invention is able to extinguishing a fire by means of a very small quantity of water.

That implies that fire-extinguishing devices equipped with nozzle heads according to the invention can be so light and occupy so little place that it can be carried of a person, e.g. in a backpack.

A small vehicle such as e.g. a motorcycle also can be used for transporting a fire-extinguishing device with the nozzle head of the invention. This will reach the scene of the fire faster than a fire engine even through heavy traffic in a big city.

A fire-extinguishing device equipped with the nozzle head of the invention can also conveniently be placed in a car, on an aircraft, or a boat, and at not very accessible ski resorts, e.g. a snow scooter can be used for transporting the fire- extinguishing device to the scene of the fire.

Example

In order to evaluate the ability of the nozzle head according to the invention to extinguish fires in high tensions areas, i.e. up to 20.000 V, an Insulation Resistance Test was used.

An Insulation Resistance Test is a Hipot test. Hipot is an abbreviation for high potential. Traditionally, Hipot is a term given to a class of electrical safety testing instruments used to verify electrical insulation in finished appliances, cables or other wired assemblies, printed circuit boards, electric motors, and transformers.

Under normal conditions, any electrical device will produce a minimal amount of leakage current due to the voltages and

internal capacitance present within the product. Yet due to design flaws or other factors, the insulation in a product can break down, resulting in excessive leakage current flow. This failure condition can cause shock or death to anyone that comes into contact with the faulty product.

A Hipot test (also called a Dielectric Withstand test) verifies that the insulation of a product or component is sufficient to protect the operator from electrical shock. In a typical Hipot test, high voltage is applied between a product's current- carrying conductors and its metallic chassis. The resulting current that flows through the insulation, known as leakage current, is monitored by the tester. The theory behind the test is that if a deliberate over-application of test voltage does not cause the insulation to break down, the product will be safe to use under normal operating conditions - hence the name, Dielectic Withstand test.

In addition to over-stressing the insulation, the test can also be performed to detect material and workmanship defects, most importantly small gap spacings between current-carrying conductors and earth ground. When a product is operated under normal conditions, environmental factors such as humidity, dirt, vibration, shock and contaminants can close these small gaps and allow current to flow. This condition can create a shock hazard if the defects are not corrected at the factory. No other test can uncover this type of defect as well as the Dielectric Withstand test. Three types of Hipot tests are commonly used. Dielectric breakdown Test, Dielectric Withstand Test. And the Insulation Resistance Test. The tests differ in the amount of voltage applied and the amount of acceptable current flow.

The Insulation Resistance Test is used to provide a quantifiable resistance value for all of a product's insulation. The test voltage is applied in the same fashion as a standard Hipot test, but is specified to be Direct Current (DC) . The voltage and measured current value are used to calculate the resistance of the insulation.

For the Insulation Resistance Test a ISOL 5002 Insulation Tester was used with the following specifications.

ISOL 5002 Insulation Tester

Specifications

DC Test Voltage (4 ranges) : 500V/1000V/2500V/5000V

Constant current: 33 μA (1300 V max)

Automatrc Discharge: Timer

Voltage measure function: 0 ~ 600 V (AC/DC) unit Measuring DC test Accuracy Average Discharge Max. Overload range Voltage and charging time time Overload Time current

Kω 10 Kω ~ Max . 1300 V, 5 % of From 0.4 to 5 0.5 sec/μF Arbitrarily Continuous 30000 Kω Fixed current Reading sec/μF two terminal

33 μA Value (10 % according to electric of Nax . different voltages is

Mω 30 Kω ~ 500 V, Value) or 5 test voltage 600 V 30000 Kω 1000 V, Kω 2500 V,

Gω Gω - 3000 5000 V Gω (I < 6 HiA)

Giving the following results with the nozzle head according to the invention.

Furthermore, a Puncture and Insulation Tester with the following specifications was used for evaluating the

Giving the following results with the nozzle head according to the invention.

The Insulating gloves used in both examples has the following specifications: EN 60903 2003 CE Class 0 AZC Max. use voltage 1000 V. AC, RMS Novax made in Malaysia.

The insulation on the insulating nozzle is thin layer of latex.

As is evident from the example above the nozzle head according to the invention is capable of extinguish fires m high tensions areas, i.e. up to 10.000 V with the specification in the present examples. Thus, a person skilled in the art could, based on the information m the present application easily modify the nozzle according to the invention in order to obtain a nozzle head capable of extinguish fires in high tensions areas up to 10.000 V.