FIRE EXTINGUISHING LIQUID

Abstract

A fire extinguishing liquid is described which includes one or more of a phosphate, hydrogen phosphate or dihydrogen phosphate salt; and a sulphate salt. The fire extinguishing liquid contains no, or substantially no, hydrogen carbonate salts. The liquid finds use in the extinguishment of fires, including battery fires.

Claims

1. A fire extinguishing liquid comprising: (a) one or more of a phosphate, hydrogen phosphate or dihydrogen phosphate salt; and (b) a sulphate salt; wherein the fire extinguishing liquid contains no, or substantially no, hydrogen carbonate salts.

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

3. A fire extinguishing liquid according to claim 2, wherein the liquid vehicle is water.

4. A fire extinguishing liquid according to claim 3, wherein the water is demineralized water.

5. A fire extinguishing liquid according to claim 4, wherein the fire extinguishing liquid comprises 65% to 75% water by weight.

6. A fire extinguishing liquid according to any one of claims 3 to 5, 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.

7. A fire extinguishing liquid according to any one of claims 1 to 6, 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 (b), is from 3:1 to 15:1.

8. A fire extinguishing liquid according to any one of claims 1 to 7, wherein the one or more of a phosphate, hydrogen phosphate or dihydrogen phosphate salt comprises or consists of diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4).

9. A fire extinguishing liquid according to claim 8, wherein the fire extinguishing liquid comprises 15% to 25% diammonium hydrogen phosphate by weight.

10. A fire extinguishing liquid according to any one of claims 1 to 9, wherein the sulphate salt comprises or consists of ammonium sulphate ((NH.sub.4).sub.2SO.sub.4).

11. A fire extinguishing liquid according to claim 10, wherein the fire extinguishing liquid comprises 2% to 3% ammonium sulphate by weight.

12. A fire extinguishing liquid according to claim 11, wherein the weight ratio of diammonium hydrogen phosphate to ammonium sulphate in the extinguishing liquid is at least 2:1, preferably at least 3:1.

13. A fire extinguishing liquid according to any one of claims 1 to 12, further including a firefighting foam component.

14. A fire extinguishing liquid according to claim 13, wherein the firefighting foam component includes a surfactant.

15. A fire extinguishing liquid according to claim 14, wherein the firefighting foam component is an alcohol-resistant aqueous film forming foam (AR-AFFF).

16. A fire extinguishing liquid according to any one of claims 13 to 15, wherein the fire extinguishing liquid comprises 4% to 5% firefighting foam component by weight.

17. A fire extinguishing liquid according to any one of claims 1 to 16, wherein the fire extinguishing liquid contains no hydrogen carbonate salts, or contains hydrogen carbonate salts in an amount of less than 100 ppm by weight, based on the total weight of the fire extinguishing liquid.

18. A fire extinguishing liquid comprising: (a) one or more of a phosphate, hydrogen phosphate or dihydrogen phosphate salt, wherein the total amount of phosphate, hydrogen phosphate and dihydrogen phosphate salt is from 20 to 25 wt %, based on the total weight of the fire extinguishing liquid; and (b) a sulphate salt, wherein the total amount of sulphate salt is from 2 to 3 wt %, based on the total weight of the fire extinguishing liquid.

19. A fire extinguishing liquid according to claim 18, wherein the fire extinguishing liquid contains no, or substantially no, hydrogen carbonate salts.

20. A fire extinguishing liquid according to claim 18 or 19, wherein the fire extinguishing liquid comprises 20 to 22 wt % phosphate, hydrogen phosphate or dihydrogen phosphate salt.

21. A fire extinguishing liquid according to any one of claims 18 to 20, wherein the fire extinguishing liquid comprises 2.6 to 2.8 wt % sulphate salt.

22. A method of manufacturing a fire extinguishing liquid according to any one of claims 1 to 21 comprising the step of mixing (a) one or more of a phosphate, hydrogen phosphate or dihydrogen phosphate salt; (b) a sulphate salt; and a liquid vehicle.

23. A method according to claim 22, wherein component (a) is diammonium hydrogen phosphate ((NH.sub.4).sub.2HPO.sub.4), and component (b) is ammonium sulphate ((NH.sub.4).sub.2SO.sub.4).

24. A method according to claim 22 or 23, wherein the liquid vehicle is water.

25. A method according to any one of claims 22 to 24, the method comprising the steps of: (i) heating water to 30 C. to 70 C.; (ii) adding diammonium hydrogen phosphate and mixing until dissolved; and (iii) adding ammonium sulphate and mixing until dissolved.

26. A method according to claim 25, further comprising the steps: (iv) cooling the mixture of water, diammonium hydrogen phosphate and ammonium sulphate to below 25 C.; and (v) filtering to remove undissolved residue.

27. A method according to any one of claims 22 to 26, wherein the phosphate, hydrogen phosphate or dihydrogen phosphate salt, and sulphate salt are added in solid form.

28. A method according to any one of claims 22 to 27, further including the step of adding a firefighting foam component.

29. A method according to any one of claims 22 to 28, further including the step of filling a fire extinguisher with the fire extinguishing liquid.

30. A method according to claim 29, wherein the filtering step is performed as the fire extinguisher is being filled.

31. A fire extinguishing liquid made by a method according to any one of claims 22 to 30.

32. A fire extinguisher containing the fire extinguishing liquid of any one of claims 1 to 21.

33. A method of extinguishing a fire using a fire extinguishing liquid of any one of claims 1 to 21.

Description

EXAMPLES

Example 1

[0209] A fire extinguishing liquid was prepared according to the following method: [0210] 1) demineralized water was run into a mixing vessel, and heated to 40 C. using an electric element located within the mixing vessel. [0211] 2) 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. 25 [0212] 3) ammonium sulphate was added while mixing. After all of the ammonium sulphate was dissolved, the solution was mixed for a further 30 minutes. [0213] 5) AR-AFFF was added (Non-Newtonian 33% AR-AFFF manufactured by Aberdeen Foam), while slowly mixing (to avoid foaming). The mixture was allowed to cool to below 25 C., and was then passed through a 20 m filter and the filtrate was passed directly into a fire extinguisher vessel.

[0214] The quantities of each ingredient were measured so that the amounts of each component in the final composition fell within the following ranges, based on the total weight of the overall composition: 20 to 22 wt % diammonium hydrogen phosphate; 3 to 5 wt % AR-AFFF; 2.6 to 2.8 wt % ammonium sulphate; and 65 to 75 wt % deionised/demineralised water.

[0215] A 6-litre steel Commander Edge Extinguisher was filled with the liquid and nitrogen gas was added as propellant. The extinguisher included a foam rose nozzle. The extinguisher was used on a range of fire types and the results are provided in Table 1 below.

TABLE-US-00001 TABLE 1 Time until complete Fire type extinguishment Two 14.8 V laptop batteries <5 seconds Six 14.8 V laptop batteries <10 seconds 36 V e-scooter battery <5 seconds 12 L diesel <5 seconds 3 L petrol <5 seconds 2 L bioethanol <5 seconds

[0216] The results show that the liquid is able to effectively extinguish a range of different fire types, including battery fires, despite the lack of any hydrogen carbonate salt.

[0217] 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.

[0218] All references referred to above are hereby incorporated by reference.