Patent Publication Number: US-2007095547-A1

Title: Fire extinguishers

Description:
The invention relates to fire extinguishers. Preferably, but not exclusively, the fire extinguishers of the invention are portable.  
      Hand held fire extinguishers having a discharge member for directing an extinguishing agent from the extinguisher towards a target are well known. For example, in the case of a carbon dioxide fire extinguisher, the discharge member may be a conical horn which directs the carbon dioxide towards a fire. In the case of a water fire extinguisher, the discharge member may be nozzle, provided on a flexible hose, by which the water can be directed towards a fire.  
      Hitherto during operation of hand held fire extinguishers, the user simply points the discharge member towards the target fire. In some circumstances, it is desirable to be able to aim the discharge member towards the target fire in a more accurate manner.  
      In accordance with an aspect of the invention, there is provided a fire extinguisher having a discharge member for directing an extinguishing agent from the extinguisher towards a target, the extinguisher also having at least one light beam director for directing a beam of light in a predetermined direction relative to the discharge member so that the discharge member can be aimed at a target by directing the light beam at or adjacent to the target.  
      It can be even more important to give the user of a hand held fire extinguisher some indication of the correct distance to stand away from the fire to ensure maximum effectiveness of the fire extinguisher.  
      In accordance with a preferred embodiment of the invention, the fire extinguisher described above includes two light beam directors for directing respective light beams in respective predetermined directions relative to the discharge member so that the light beams substantially cross one another and so that the discharge member can be aimed at a target and positioned at a desired distance from the target by moving the discharge member so that the light beams substantially cross one another at or adjacent to the target. 
    
    
      The following is a more detailed description of embodiments of the invention, by way of example, reference being made to the appended schematic drawings in which:  
       FIG. 1  is a representation of a first carbon dioxide fire extinguisher;  
       FIG. 2  is a representation of a first water fire extinguisher;  
       FIG. 3  is a representation of a second water fire extinguisher; and  
       FIG. 4  is a representation of a second carbon dioxide fire extinguisher.  
    
    
      Looking at  FIG. 1 , the first carbon dioxide fire extinguisher  10  comprises a main body  11 , which holds the carbon dioxide extinguishing agent, a discharge member in the form of a discharge horn  12 , a valve  13  and upper and lower handles  14 ,  15  which operate the valve  13 . In a known manner, the discharge horn  12  is mounted for pivotal movement adjacent the valve  13  so that the angle of the discharge horn  12  relative to the main body  11  can be changed by manually moving the discharge horn  12 .  
      The main body  11 , the discharge horn  12 , the valve  13  and the upper and lower handles  14 ,  15  are all well known.  
      A bracket  16  is fixedly mounted to the discharge horn  12 . The bracket  16  has a first arm  16   a  which extends in a first direction away from the discharge horn  12 , and a second arm  16   b,  which extends away from the discharge horn  12  in a second direction which is diametrically opposed to the first direction. A first LED laser diode  17  is fixedly mounted at the outer end of the first arm  16   a  of the bracket  16 . A second LED laser diode  18  is fixedly mounted at the outer end of the second arm  16   b  of the bracket  16 . Accordingly, as seen in  FIG. 1 , the first and second LED laser diodes  17 ,  18  are spaced from one another by a significant distance.  
      The first and second LED laser diodes  17 ,  18  are both connected in a simple electrical circuit (not shown) which also includes a battery (not shown) and a push button switch (not shown). Operation of the push button switch, which may be situated, for example, on the upper handle  14 , closes the circuit so that the battery energises the LED laser diodes  17 ,  18  and causes the laser diodes  17 ,  18  to emit respective laser beams  19 ,  20 .  
      As seen in  FIG. 1 , the first and second LED laser diodes  17 ,  18  are fixedly aligned so that they direct their respective laser beams  19 ,  20  so that the laser beams  19 ,  20  cross one another at an intersection point  21 . The laser beams  19 ,  20  are directed in respective directions relative to the discharge horn  12  so that the intersection point  21  lies in line with the conical axis of the discharge horn  12  at a distance from the end of the discharge horn  12  which corresponds to the ideal distance for positioning the discharge horn  12  away from a fire in order to extinguish the fire with optimum effectiveness. When the extinguisher is operated the intersection or crossing point  21  lies in the middle of the stream of carbon dioxide.  
      In operation, after the carbon dioxide extinguisher  10  has been prepared for use (e.g. by removing the safety pin), the carbon dioxide extinguisher  10  is held approximately in the correct position relative to a fire to be extinguished. At this stage, the user presses the push button so as to energise the LED laser diodes  17 ,  18  which generate and direct the two laser beams  19 ,  20 . If, for example, the source of the fire is an item of electrical equipment, the user moves the fire extinguisher  10  (thereby moving the discharge horn  12  and LED laser diode  17 ,  18 ) until both laser beams  19 ,  20  are visible on the item of electrical equipment. The beams will be visible as small dots of light. The user then moves the fire extinguisher  10  backwards or forwards so that the two dots corresponding to the two laser beams  19 ,  20  converge. At this stage, the intersection point  21  lies on the item of electrical equipment which is burning. The user then operates the upper and lower handles  14 ,  15  so as to operate the fire extinguisher  10  in the usual way. Carbon dioxide from the main body  11  is discharged through the discharge horn  12  towards the item of electrical equipment. By moving the fire extinguisher  10  so that the laser beams  19 ,  20  cross at the item of electrical equipment, the user ensures that the discharge horn  12  is both aimed accurately at the electrical item, and is also positioned at the ideal distance away from the electrical item. This may help to-improve the effectiveness with which the fire extinguisher  10  extinguishes the fire.  
      In  FIG. 2 , a water fire extinguisher  22  has a main body  23 , which contains the water extinguishing agent, a discharge member  24  in the form of a nozzle, a flexible hose  25  which connects the nozzle  24  to the main body  23 , a valve  26  and upper and lower handles  27 ,  28 . The structure and operation of the components of the water fire extinguisher  22  described so far are well known.  
      A single LED laser diode  29  is connected to the discharge nozzle  24  by a bracket  30 . The LED laser diode is connected in a simple electrical circuit (not shown) containing a battery (not shown) and a push button switch (not shown) as for the carbon dioxide fire extinguisher  10  shown in  FIG. 1 . When the push button switch is operated, the circuit is closed and the battery energises the LED laser diode  29  to produce a laser beam  31 . The LED laser diode  29  directs the laser beam  31  so that the laser beam  31  lies generally parallel and close to the stream of water discharged from the nozzle  24 .  
      In operation, after the water fire extinguisher  22  has been prepared for use, the push button is pressed so as to energise the LED laser diode  29  so as to produce the laser beam  31 . The discharge nozzle  24  is then moved, which is possible without movement of the main body  23  by virtue of the flexible hose  25 , so that the laser beam  31  is visible as a small dot at the location where the water is desired to extinguish the fire. The valve  26  is then operated via the handles  27 ,  28 , in the usual manner, so that the water is expelled through the flexible hose  25  and the discharge nozzle  24  towards the fire. The stream of water hits the fire at the place where the laser beam dot was positioned. In this way, the water is accurately aimed at the required position.  
      It will be appreciated that, although the LED laser diode  29  allows the discharge nozzle  24  to be aimed more accurately at the fire, this system does not give the user any information about the preferred distance from the fire, as there is only a single laser beam  31 .  
       FIG. 3  shows a second water fire extinguisher  32  which is similar to the water fire extinguisher  22  shown in  FIG. 2 . For convenience, features of the second water fire extinguisher  32  which are identical to the corresponding features of the first water fire extinguisher  22  are given the same reference numerals and are not described in detail.  
      The second water fire extinguisher  32  has a bracket  33  which is mounted on the flexible hose  25  adjacent to and spatially fixed relative to the discharge nozzle  24 . The bracket  33  has a first arm  33   a  and a second arm  33   b —the first and second arms  33   a,    33   b  extending away from one another in diametrically opposed directions from the hose  25 . A first LED laser diode  34  is fixedly mounted on the outer end of the first arm  33   a  and a second LED laser diode  35  is fixedly mounted on the outer end of the second arm  33   b.    
      As for the previous embodiments, the first and second LED laser diodes  34 ,  35  are connected in a circuit (not shown) also including a battery (not shown) and a push button switch (not shown), so that operation of the switch causes the battery to energise the LED laser diodes  34 ,  35  so that they emit respective laser beams  36 ,  37 .  
      As shown in  FIG. 3 , the first and second LED laser diodes  34 ,  35  are fixed relative to one another so that the laser beams  36 ,  37  cross one another at a point of intersection  38 . The point of intersection  38  lies on the path of the stream of water when the water is discharged through the nozzle  24 . Additionally, the point of intersection  38  is located at a distance from the discharge nozzle  24  which is the preferred distance between the nozzle  24  and the fire for the purposes of extinguishing the fire.  
      In operation, the water fire extinguisher  32  is used in a similar manner to the carbon dioxide extinguisher  10  shown in  FIG. 1 . In other words, before water is discharged from the extinguisher  32 , the LED laser diodes  34 ,  35  are activated so that they direct their respective laser beams  36 ,  37  as shown in  FIG. 3 . The discharge nozzle  24  is moved (and the main body  32  may also be moved) so that the two dots corresponding to the laser beams  36 ,  37  are brought into coincidence at the target position. In other words, the discharge nozzle  24  is moved so that the laser beams  36 ,  37  cross at the desired target for the water. The handles  27  and  28  are then operated so that water is discharged through the discharge nozzle  24 , the water being directed accurately at the position of the intersection point  38 .  
      A second carbon dioxide fire extinguisher  39  is shown in  FIG. 4 . The main body  11 , the valve  13 , and the upper and lower handles  14 ,  15  are identical to the corresponding components of the first carbon dioxide extinguisher  10  shown in  FIG. 1 . These components are given the same reference numerals and are not described in detail. The second carbon dioxide fire extinguisher  39  also has a discharge horn  41  which differs from the discharge horn  12  shown in  FIG. 1  in that the discharge horn  41  is positioned at a fixed angle relative to the main body  11 .  
      The second carbon dioxide fire extinguisher  39  also has first and second LED laser diodes  42 ,  43  which are fixed directly to the main body  11 . Again, as for the previous embodiments, the LED laser diodes  42 ,  43  are included in an electrical circuit (not shown) which also includes a push button switch (not shown) and a battery (not shown).  
      As seen in  FIG. 4 , the first and second LED laser diodes  42 ,  43  are aligned so that the laser beams  44 ,  45  which they generate and direct cross at an intersection point  46 . This intersection point  46  lies on the axis of the conical discharge horn  41 , at a distance from the end of the discharge horn  41  which corresponds to the desired distance of the discharge horn  41  from the fire.  
      The second carbon dioxide fire extinguisher  39  is used in a similar manner to the first carbon dioxide extinguisher  10 .  
      It will be appreciated that in the second carbon dioxide fire extinguisher  39 , because the position of the discharge horn  41  is fixed relative to the main body  11 , the point of intersection  46  will always be in the desired position relative to the discharge horn  41 .  
      In the fire extinguishers  10 ,  22 ,  32  shown in FIGS.  1  to  3 , the LED laser diodes  17 ,  18 ,  29 ,  34 ,  35  are mounted in a fixed spatial relationship relative to the discharge members (the discharge horn  12  in  FIG. 1 , and the discharge nozzles  24  in  FIGS. 2 and 3 ), so that the LED laser diodes remain correctly aligned relative to the discharge members  12 ,  24  even when the discharge members  12 ,  24  are moved relative to the main bodies  11 ,  23 .  
      Where there are two LED laser diodes, then the two LED laser diodes should preferably be mounted sufficiently far from one another so that the angle between the laser beams is sufficiently great so as to allow the intersection point to be readily ascertained visually. For example, when the desired distance from the discharge member to the fire is about 12 feet (3.66 m), then the laser diodes are preferably at least 6 inches (15.2 cm) apart and more preferably at least 12 inches (30.5 cm) apart. A spacing of 6 inches (15.2 cm) between the laser diodes gives a light beam dot spacing of about 0.5 inches (1.27 cm) for each foot (30.5 cm) difference between the desired 12 feet distance and the actual distance. A spacing of 12 inches (30.5 cm) between the laser diodes gives a light beam spot spacing of about 1 inch (2.35 cm) for each foot (30.5 cm) difference between the desired 12 foot distance and the actual distance. If the discharge member is fixed relative to the main body, then the desired spacing between the diodes can generally be achieved by mounting the laser diodes on the main body, as in the case of the second carbon dioxide extinguisher  39  shown in  FIG. 4 . More normally, however, the discharge member is movable relative to the main body. In this case, although it is desirable to mount the LED laser diodes in a fixed spacial relationship to the discharge member, the discharge member may not itself be sufficiently wide so as to allow the desired spacing of the diodes if the diodes are mounted directly on the discharge member. This problem can be solved by using a bracket or the like which allows the desired spacing to be achieved, as shown in the extinguisher  10 ,  32  of  FIGS. 1 and 3 . Another possibility, in cases where the discharge member moves relative to the main body, is to mount the diodes with the desired spacing on the main body and provide means to ensure that the discharge member is located in the correct alignment relative to the laser diodes during use. For example a movable horn for a carbon dioxide extinguisher could be provided with a stop to stop pivotal movement of the horn relative to the main body at the correct position of the horn relative to the laser diodes.  
      It will be appreciated that the invention may be adapted in many other ways. For example, the invention is not limited to water and carbon dioxide fire extinguishers. It may be applied to any type of fire extinguisher having a discharge member for directing an extinguishing agent from the extinguisher towards a target. For example, the fire extinguisher may be of the dry chemical, vaporising liquid or foam varieties.  
      Instead of LED laser diodes, any suitable type of light source producing a light beam may be used. In cases where there are two light beams, it is not be necessary to have two light sources. For example a single laser beam generator may be used, with two fibre optic cables being used to direct two beams from the generator in different directions. Alternatively, a single light source may be split into two light beams using a beam splitter or half silvered mirror.  
      The mounting brackets  16 ,  30  and  33  need not be as described above and may take any suitable form.  
      Although the invention is described with reference to hand held fire extinguishers, the extinguisher of the invention need not be hand held. In this case, the discharge member will preferably be movable relative to the body holding the extinguishing agent. Examples of non-hand held fire extinguishers to which the current invention may be applied are wheeled units and fire fighting hoses.