FIRE EXTINGUISHING LIQUID

Abstract

A fire extinguishing liquid comprising: one or more of a phosphate, hydrogen phosphate or dihydrogen phosphate salt; a hydrogen carbonate salt; and a sulphate salt.

Claims

1. A fire extinguishing liquid comprising: (a) one or more of a phosphate, hydrogen phosphate or dihydrogen phosphate salt; (b) a hydrogen carbonate salt; and (c) a sulphate salt.

2. The fire extinguishing liquid according to claim 1, further comprising monopropylene glycol (C.sub.3H.sub.8O.sub.2).

3. The fire extinguishing liquid according to claim 1, wherein the salts are all dissolved in a liquid vehicle.

4. The fire extinguishing liquid according to claim 3, wherein the liquid vehicle is water, the water optionally being demineralized water.

5. (canceled)

6. The fire extinguishing liquid according to claim 1, wherein the molar ratio in the fire extinguishing liquid of the phosphate, hydrogen phosphate or dihydrogen phosphate anion in (a), to the hydrogen carbonate anion in (b), is from 5:1 to 20:1.

7. The fire extinguishing liquid according to claim 1, wherein the molar ratio in the fire extinguishing liquid of the phosphate, hydrogen phosphate or dihydrogen phosphate anion in (a), to the sulphate anion in (c), is from 3:1 to 15:1.

8. The fire extinguishing liquid according to claim 1, wherein the molar ratio in the fire extinguishing liquid of the phosphate, hydrogen phosphate or dihydrogen phosphate anion in (a), to the propylene glycol in (d), is from 0.3:1 to 0.8:1.

9. The fire extinguishing liquid according to claim 4, wherein the molar ratio in the fire extinguishing liquid of the phosphate, hydrogen phosphate or dihydrogen phosphate anion in (a), to water, is from 0.01:1 to 0.5:1.

10. The fire extinguishing liquid according to claim 1, wherein: the hydrogen phosphate salt comprises diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4), the carbonate salt comprises ammonium bicarbonate (NH.sub.4HCO.sub.3), and the sulphate salt comprises ammonium sulphate ((NH.sub.4).sub.2SO.sub.4).

11. The fire extinguishing liquid according to claim 10, wherein the weight ratio of diammonium hydrogen phosphate to ammonium bicarbonate in the extinguishing liquid is at least 3:1, preferably at least 4:1.

12. A fire extinguishing liquid according to claim 10, wherein the weight ratio of diammonium hydrogen phosphate to ammonium sulphate in the extinguishing liquid is from 2:1 to 8:1.

13. A fire extinguishing liquid according to claim 4, wherein the fire extinguishing liquid comprises 50% to 70% water by weight, optionally 55% to 65% water by weight, optionally 58% to 60% water by weight.

14. (canceled)

15. (canceled)

16. The fire extinguishing liquid according to claim 10, wherein the fire extinguishing liquid comprises 10% to 30% diammonium hydrogen phosphate by weight, optionally 15% to 25% diammonium hydrogen phosphate by weight, optionally 16% to 20% diammonium hydrogen phosphate by weight.

17. (canceled)

18. (canceled)

19. A fire extinguishing liquid according to claim 10, wherein the fire extinguishing liquid comprises 0.01% to 5% ammonium bicarbonate by weight, optionally 0.5% to 3% ammonium bicarbonate by weight, optionally 1% to 2% ammonium bicarbonate by weight.

20. (canceled)

21. (canceled)

22. A fire extinguishing liquid according to claim 10, wherein the fire extinguishing liquid comprises 0.01% to 10% ammonium sulphate by weight, optionally 2% to 5% ammonium sulphate by weight, optionally 3% to 4% ammonium sulphate by weight.

23. (canceled)

24. (canceled)

25. A fire extinguishing liquid according to claim 2, wherein the fire extinguishing liquid comprises 10% to 20% monopropylene glycol by weight, optionally 12.5% to 17.5% monopropylene glycol by weight, optionally 15% to 17% monopropylene glycol by weight.

26. (canceled)

27. (canceled)

28. A fire extinguishing liquid according to claim 1, further including a firefighting foam component.

29. A fire extinguishing liquid according to claim 28, wherein the firefighting foam component includes a surfactant.

30. A fire extinguishing liquid according to claim 29, wherein the firefighting foam component is an aqueous film forming foam (AFFF).

31. A fire extinguishing liquid according to claim 28, wherein the fire extinguishing liquid comprises 2% to 12% firefighting foam component by weight, optionally 6 to 12% firefighting foam component by weight.

32-42. (canceled)

43. A fire extinguisher containing the fire extinguishing liquid of claim 1.

44-45. (canceled)

46. A method of extinguishing a fire, comprising applying the fire extinguishing liquid of any claim 1 to the fire.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0148] Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

[0149] FIG. 1 is a graph of temperature, as measured at three positions within a fire, plotted against the period of time from initiation of the extinguishing process up to complete extinguishment with an extinguishing liquid according to the invention.

[0150] FIG. 2 is a graph of temperature, as measured at three positions within a fire, plotted against the period of time from initiation of the extinguishing process up to complete extinguishment with water alone.

EXAMPLES

Example 1

[0151] A fire extinguishing liquid was prepared according to the following method: [0152] 1) 727 kg of demineralized water was run into a mixing vessel, and heated to 40° C. using an electric element located within the mixing vessel. [0153] 2) 350 kg of diammonium hydrogen phosphate was added slowly to the demineralized water in batches, allowing each batch to dissolve before making another addition. Thereafter, the solution was mixed for 15 to 20 minutes until the last of the diammonium hydrogen phosphate was dissolved. [0154] 3) 30 kg of ammonium bicarbonate was added while mixing. After all of the ammonium bicarbonate was dissolved, the solution was mixed for a further 10 minutes. [0155] 4) 80 kg of ammonium sulphate was added while mixing. After all of the ammonium sulphate was dissolved, the solution was mixed for a further 30 minutes. [0156] 5) 50.75 kg of FOMTEC® AFFF 3% was added, while slowly mixing (to avoid foaming). The mixture was allowed to cool to below 25° C., and was then passed through a 20 μm filter and the filtrate was passed directly into a fire extinguisher vessel.

Example 2

[0157] A fire extinguishing liquid was prepared according to the following method: [0158] 1) 727 kg of demineralized water was run into a mixing vessel, and heated to 60° C. using an electric element located within the mixing vessel. [0159] 2) 210 kg of diammonium hydrogen phosphate was added slowly to the demineralized water in batches, allowing each batch to dissolve before making another addition. Thereafter, the solution was mixed for 15 to 20 minutes until the last of the diammonium hydrogen phosphate was dissolved. [0160] 3) 20 kg of ammonium bicarbonate was added while mixing. After all of the ammonium bicarbonate was dissolved, the solution was mixed for a further 10 minutes. [0161] 4) 48 kg of ammonium sulphate was added while mixing. After all of the ammonium sulphate was dissolved, the solution was mixed for a further 30 minutes. [0162] 5) 202.3 kg of monopropylene glycol was added while mixing, and the solution was stirred until fully dissolved. [0163] 6) 30.45 kg of FOMTEC® AFFF 3% was added, while slowly mixing (to avoid foaming). The solution was then mixed and circulated for a further 30 minutes.

[0164] The mixture was allowed to cool to 18° C., and was then passed through a 20 μm filter and the filtrate was passed directly into a fire extinguisher vessel.

[0165] The following examples show that the extinguishing liquid of the invention is useful in fighting fires of at least Classes A, B, D and F.

Example 3

[0166] The liquid made in Example 1 was tested for fire extinguishing ability using fire performance tests according to section 15 of European standard EN 3-7:2004+A1:2007.

[0167] In a first test, the liquid was tested in a 6 L stored pressure extinguisher (N.sub.2—15 bar/20° C.) with inner nozzle diameter of 6×2 mm. The results showed that the fire rating of the extinguisher was 34 A (with an extinguishing time of 148 s) and 75 F (with an extinguishing time of 2 s).

[0168] In a second test, the liquid was tested in a 2 L stored pressure extinguisher (N.sub.2—15 bar/20° C.) with inner nozzle diameter of 3×2.2 mm. The results showed that the fire rating of the extinguisher was 13 A (with an extinguishing time of 110 s) and 25 F (with an extinguishing time of 3 s).

[0169] The ratings for a number of typical comparative fire extinguishing media are provided below:

TABLE-US-00001 Extinguishing medium Size Rating CO.sub.2 2 kg 34 B 5 kg 70 B Dry powder 1 kg 8A; 34B 2 kg 13A; 89B  3 kg 21A; 113B 4 kg 27A; 144B 6 kg 43A; 233B 9 kg 55A; 233B 12 kg 55A; 233B Specialist dry powder — Metal fires only Wet chemical 2 L 34B; 25F  3 L 13A; 70B; 40F 6 L 21A; 113B; 75F Water 6 L 13A 9 L 21A Water additive 3 L 13A 6 L 27A Foam 2 L 8A; 55B 3 L 13A; 89B  6 L 21A; 144B 9 L 27A; 233B

[0170] In general, powder can be used for Types A, B and C and can also show the electrical symbol. Water is for Type A only. Foam is for Types A and B. Wet chemical is for Types A, B and F. CO.sub.2 is for Type B and electrical.

[0171] In the following Examples, all test temperatures were recorded using a thermal image camera recording the peak temperature at the hottest point of the fire with a maximum fluctuation of ±20 degrees, times were recorded via a stopwatch. All tests were recorded with video footage.

Example 4—9 L Extinguisher Used on Small Domestic Fire Class A

[0172] Two separate cribs, of a similar size (approx. 1 m.sup.3), containing a mixture of wood planks, paper and straw were placed in a compartment and ignited separately. This test was designed to replicate the size and heat release rate (approx. 300 Kw-750 Kw) of a small domestic Class A compartment fire.

[0173] The first crib was placed in the centre of the room, ignited and allowed to achieve a peak temperature of 450° C. with full involvement of the wood planking. Once peak temperature was achieved an attempt was made to extinguish the fire using a 9 L water extinguisher charged to 11 bar pressure.

[0174] The second crib was placed adjacent to a large concrete structural support, this allowed for greater fire development and a higher peak temperature of 560° C. An extinguisher (‘Extinguisher A’) filled with the liquid of Example 1, with a stored pressure within the extinguisher of 15 bar, was used to extinguish the fire. All other test parameters were identical.

[0175] The water extinguisher was fully discharged in 1 min 17 s and failed to extinguish the fire, with visible flame still being observed on a number of wooden planks. The residual temperature was recorded as 250° C. with re-ignition occurring. The surface temperatures on the wooden planks were also high and didn't allow touching without a gloved hand.

[0176] Extinguisher A managed to extinguish the wood within the test fire with only small areas of burning remaining within a couple of areas of straw packing, residual temperatures were recorded at 120° C. in these areas. Surface temperatures were also reduced to such a level that it was possible to pick up wooden planks without a glove or any form of protection. It was noted that the increase in pressure resulted in a rapid discharge of the extinguisher (48 seconds) in comparison to the water extinguisher.

[0177] Despite the increase in stored pressure within Extinguisher A, resulting in faster discharge times, the test results show that Extinguisher A clearly outperformed a similar water extinguisher when utilised on a Class A fire.

Example 5—Larger Domestic Fire (Sofa) Extinguished Using Hose Reel Jet (25 bar)

[0178] A 3 seat sofa of modern design and meeting current standards was placed against the rear internal wall of a test compartment and ignited. An initial test was conducted to establish a base line using a 25 bar hose reel jet and water from a peak temperature of approx. 340° C. and a heat release rate of approx. 1-3 MW.

[0179] The test was then repeated within the same parameters as the baseline test but using an induced supply of the liquid of Example 1 at 20% via the hose reel jet (‘Extinguisher B’). Higher peak temperatures of 560° C. were also recorded.

[0180] Note: Initial test were at a lower peak temperature due to external environmental effects on test compartment (steel shipping container) and the test compartment absorbing a large amount of heat from the test fires. Once these factors were overcome higher temperatures were recorded. Supplementary tests conducted in similar circumstances at a later date recorded peak temperatures of approx. 500° C.

[0181] Both fires were extinguished successfully with current operational techniques for compartment firefighting being used to address a Class A fire.

[0182] Results of temperature measurements taken from three probes positioned at varying heights within the fire are shown in FIGS. 1 and 2. FIG. 1 shows the measurements recorded through the extinguishing process when Extinguisher B was used. FIG. 2 shows the measurements recorded through the extinguishing process when water alone was used. A rapid ‘knock down’ of the fire was observed when using Extinguisher B, along with less water usage and lower residual temperatures after it was extinguished (100° C. as opposed to 200° C.).

[0183] Recorded temperatures within the supplementary tests were broadly similar with Extinguisher B, approx. 30% more efficient than water (see FIGS. 1 and 2) and an identified rapid reduction in temperature within the compartment in comparison to a similar amount of water. There was less steam, and resultant radiated heat, which allowed for a rapid entry and easier progress into the compartment with reduced physiological impact on the firefighter.

Example 6—Developed Fire in an Average Size 5 Door Family Car

[0184] An average sized 5 door family car was ignited and allowed to reach full involvement with fire located in the main passenger and engine compartment.

[0185] This test was designed to replicate similar conditions to those experienced by responding operational fire and rescue crews.

[0186] All vehicles were drained of fuel and oil, placed in open air and subject to a light breeze. All test fires were started by the ignition of internal seating via a gas powered thermal lance.

[0187] Supplementary tests repeated the test process with the addition of specific small fires within the engine and passenger compartment to allow for the testing of smaller 1 and 2 L extinguishers on ‘early stage’ vehicle fires.

[0188] The performance of 9 L extinguishers (Extinguisher C) on a developed fire within the primary test car was evaluated using extinguishers charged to 11 Bar and with a structured attack made on the fire using two extinguishers working simultaneously and in conjunction with each other. This test achieved a positive outcome with the fire controlled and extinguished using two extinguishers (a third was used to fully extinguish a small number of ‘hotspots’). This test demonstrated the potential usage of Extinguisher C (carried on smaller appliances) on this type of fire including Class A, B and D.

[0189] Supplementary tests were also conducted using smaller 1 and 2 L extinguishers containing the liquid of Example 1 on specific fires within the engine bay and passenger compartment. These tests identified that 2 L was the optimum size, and the easiest to use, for the early extinguishment of small vehicle fires before the arrival of the fire service.

Example 7—Developed Fire in an Average Size 5 Door Family Car Using a High Pressure Hose Reel Jet (100 bar)

[0190] An average sized family car was ignited and allowed to reach full involvement with fire located in the main passenger cabin and engine compartment. This fire was conducted to establish a baseline of data for water usage and environmental impact.

[0191] This test was designed to replicate similar conditions to those experienced by responding operational fire service crews.

[0192] All vehicles were drained of fuel and oil placed in open air and subject to a light breeze. All test fires were started by the ignition of internal seating via a gas powered thermal lance.

[0193] The test was conducted using water alone, and repeated using a high pressure hose reel jet (100 bar) delivering the liquid of Example 1 induced at 20% concentration (‘Extinguisher D’), all other test parameters were the same.

[0194] An additional test was conducted using a HYBRID vehicle of a similar size to test the capabilities of Extinguisher D when extinguishing a car fire containing lithium batteries.

[0195] The baseline water test extinguished the fire within 1 mine 25 s using approx. 190 L of water. Whilst this was a positive outcome it identified that additional water (approx. 250 L) was required damping down the vehicle and dealing with a number of hotspots, this also took an extended period of time (approx. 15 min of discontinuous application). Additionally there was also a large amount of fire water run off with the potential to pollute the surrounding water course.

[0196] The fire was fully extinguished by Extinguisher D, as per the baseline test fire, and within similar timescales for application (the test took 2 min 15 s). Notable differences were that less liquid was used (approx. 60-70 L), no environmental pollution was identified from water run-off and there was no residual heat retained in the vehicle requiring on-going damping down (meaning crews could be released from the incident quicker).

[0197] The test fire conducted using the HYBRID car achieved similar results to the normal car with Extinguisher D extinguishing the fire using approx. 60-70 L of extinguishing liquid. The fire was well developed but it was not possible to confirm if the batteries had become fully involved in the fire.

Example 8—Standing Fuel Fire of Approx. 4-6 m.SUP.2

[0198] A mixture of petrol and diesel was placed into a water filled tray to a depth of approx. 15-20 cm and approx. 4-6 m.sup.2 in surface area, this was ignited and allowed to reach a peak temperature of approx. 1000° C. Multiple trays were used during testing to ensure any potential build up firefighting media did not detrimentally affect observed results.

[0199] An initial baseline test was conducted using 9 L foam extinguishers.

[0200] Comparable tests were conducted using 9 L extinguishers charged to 11 Bar pressure and containing the liquid from Example 1 (‘Extinguisher E’) in a direct and indirect application, induced via a compressed air foam system and induced via an in line inductor at 2, 4 and 6% concentration mix.

[0201] Additional tests were conducted using similar sized trays, with 100% fuel (mixture of AVGAS and diesel), and extinguished using Extinguisher E. This was to replicate a running fuel fire.

[0202] The foam extinguishers were effective on the test fire, which was extinguished in 17.5 s, however significant initial ‘flash back’ was experienced with the operators having to withdraw slightly before re-applying. The foam extinguishers discharged approx. 9 L of foam to ensure the fire was fully extinguished after re-ignition occurred.

[0203] No ‘flash back’ was experienced with the Extinguisher E, applied in a combined attack, rapid ‘knock down’ was noted with the test fire extinguished in 15 s and a reduction in temperature from 1000° C. to 50° C. A notable reduction in the amount of solution was also evident (approx. 4 L was used) with no requirement to re-apply media post fire. These results were replicated on the running fuel fire tests with slight increases in solution usage identified as a result of the nature of the fire (although this was still within the capabilities of the extinguisher).

[0204] When applied via an in line inductor no significant time difference was identified between 4-6% mix ratio in extinguishing the fire (16-23 seconds), however, ‘burn back’ leading to re-ignition was noted at 4%. At 6% this was not observed and no further application of solution was required after the initial attack.

[0205] These tests identified that Extinguisher E performed well when applied to Class B fires in both bulk and pressurised extinguisher form.

Example 9—Stack of Tyres Involved in Fire

[0206] An initial test was conducted with two small stacks of tyres placed next to each other, these were then extinguished at the same time using a 9 L water extinguisher and Extinguisher C, to establish a direct performance comparison. Peak temperatures were recorded at approx. 535° C. with both fires being started via gas powered thermal lance.

[0207] The test was repeated using a larger stack of tyres, achieving a peak temperature of approx. 950° C., and extinguished using via a 25 bar hose reel jet and bulk solution from Example 1 induced at 6%.

[0208] The initial test demonstrated a rapid ‘knock down’ by Extinguisher C in comparison to water, with the tyres extinguished in 7 s compared to 15 s. There was also a comparable reduction in the amount of solution required (2-3 L instead of 9 L) to extinguish the fire and a significant reduction in polluted firewater. Residual temperatures were comparable for both extinguishers.

[0209] The second test provided comparable outcomes to the performance identified in the previous test with approx. 10 L of solution and limited water being used to extinguish the fire in 1 min 27 s and a reduction in temperature from 955° C. to 70° C.

[0210] This test confirmed the capability, although limited due to the size of test, in extinguishing a Class A fire involving tyres.

Example 10—Developed Fire in a ‘Thatch’ Roof

[0211] Three comparable timber structures were constructed and straw bales placed on the roof to a depth of approx. 400 mm, these were then secured using metal netting to replicate a traditional thatch roof construction.

[0212] All roofs were placed in open air, subjected to a light breeze and ignited via the application of a gas powered thermal lance to the boarding under the end of the roof. This was designed to replicate ignition via heat transfer from a chimney stack. Application of firefighting media was commenced when visible flame was identified on the upper outside edge of the straw.

[0213] Three tests were conducted to compare (a) water applied via a hose reel jet, (b) bulk solution from Example 1 induced at 6% and applied via compressed air foam system lance and (c) solution from Example 1 induced at 20% via an ultra high pressure lance system. All tests were of the application of firefighting media and no standard tactics such as the removal of metal netting were employed.

[0214] The application (a) had minimal impact with fire spread still being observed after the application of large quantities of water for an extended period of time.

[0215] The test (b) injected at low pressure into the thatch using the CAFS lance (but not the CAFS system) produced a slowing of combustion but not full extinguishment. Additionally it used a large amount of water and solution with resultant large amounts of fire water run-off.

[0216] Significant positive results were observed in (c), using UHPLS, into the area between unaffected and affected thatch and at an angle parallel to the roof pitch. This created a positive barrier that prevented fire spread and allowed for a direct attack to be conducted to the affected area, it was also noted that there was considerably less water used in comparison to the previous tests and no significant water run-off.

Example 11—Trials of 1 and 2 L Extinguishers on Specific Fires

[0217] Initial tests were conducted to assess the viability and practical usage of 1 and 2 L extinguishers with varying discharge nozzles containing the solution of Example 1 for specific small scale Class A and B fires.

[0218] A test was conducted to extinguish a small fire in a car engine compartment, this was designed to assess the optimum size of extinguisher required to safely deal with an ‘early stage’ car fire. This test was repeated on a small passenger compartment fire.

[0219] Various discharge nozzles were tested to find the optimum discharge spray pattern required to extinguish fires caused by petrol bombs or similar.

[0220] Testing identified that 1 L extinguishers, while extinguishing the fire, provided no safety margin in case of unplanned fire development or a requirement for multiple applications.

[0221] Despite the slight increase in weight and size no significant detrimental effect was identified with the larger extinguisher, however, safety was increased and multiple applications were possible. Optimum extinguisher size was therefore identified as 2 L.

[0222] The optimum discharge nozzle was identified as a narrow angled cone producing a medium coarseness spray, other designs resulted in either to wider spray, limited throw or a combination of both.

Example 12—Pan fire

[0223] Tests were conducted on cooking pan fires using pan fire extinguisher sachets containing the solution of Example 1, these worked well, extinguishing a chip pan fire in a matter of seconds. It was also easy to use and produced no risk for the person applying it.

Example 13

[0224] In the Example, the fire extinguishing liquid made in Example 2 was tested to determine its freezing properties.

[0225] The freezing point of the liquid was found to be −20° C. The liquid is therefore suitable for use in low-temperature environments.

[0226] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0227] All references referred to above are hereby incorporated by reference.