LONG-TERM STORAGE OF POTABLE WATER IN METALLIC VESSELS

• US 20110139632A1
• Filed: 12/10/2009
• Published: 06/16/2011
• Est. Priority Date: 12/10/2009
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Space Systems International Inc (Rtx Corporation)
• Original Assignee: Hamilton Sundstrand Corporation (Rtx Corporation)
• Inventors: Steele, John W., Beringer, Durwood Mace, Nalette, Timothy A.
• Granted Patent: US 8,685,257 B2
• Time in Patent Office: Days
• US Class Current: 205/740
• CPC Class Codes: B64G 1/12 manned
• CPC Class Codes: B64G 1/60 Crew or passenger accommodations
• CPC Class Codes: B64G 1/66 Arrangements or adaptations of apparatus or instruments, not otherwise provided for
• CPC Class Codes: C02F 1/505 by oligodynamic treatment
• CPC Class Codes: C22F 1/10 of nickel or cobalt or alloys based thereon
• CPC Class Codes: C23C 8/10 Oxidising
• CPC Class Codes: C23C 8/40 using liquids, e.g. salt baths, liquid suspensions

Abstract

A method for controlling microbial growth in potable water stored in a vessel having a metallic surface includes heating the metallic surface to a temperature between about 480° C. (900° F.) and about 870° C. (1600° F.), exposing the metallic surface to oxygen during heating to oxidize potential reduction sites on the metallic surface and charging potable water containing silver ions to the vessel. A vessel having a metallic surface is prepared for long-term storage of potable water containing silver ions by heating the metallic surface to a temperature between about 480° C. (900° F.) and about 870° C. (1600° F.) and exposing the metallic surface to oxygen during heating to oxidize electropositive metals on the metallic surface or by treating the metallic surface with an aqueous solution containing on oxidizing agent to oxidize potential reduction sites on the metallic surface.

Claims

1. A method for controlling microbial growth in potable water stored in a vessel having a metallic surface, the method comprising:

heating the metallic surface of the vessel to a temperature between about 480°

C. (900°

F.) and about 870°

C. (1600°

F.);

exposing the metallic surface of the vessel to oxygen during heating to oxidize potential reduction sites on the metallic surface; and

charging potable water containing silver ions to the vessel.

2. The method of claim 1, wherein the metallic surface of the vessel is heated to a temperature between about 480°

C. (900°

F.) and about 870°

C. (1600°

F.) for between about 1 hour and about 24 hours.

3. The method of claim 1, wherein the metallic surface of the vessel is exposed to air at a temperature between about 480°

C. (900°

F.) and about 870°

C. (1600°

F.) for a period of time between about 60 minutes and about 4 hours to oxidize potential reduction sites on the metallic surface.

4. The method of claim 1, wherein the potable water charged to the vessel contains silver ions at a concentration between about 0.02 ppm and about 0.4 ppm.

5. The method of claim 1, further comprising:

treating the metallic surface of the vessel with a solution containing an oxidizing agent after heating the metallic surface and exposing the metallic surface to oxygen to further oxidize potential reduction sites on the metallic surface.

6. The method of claim 5, wherein the metallic substrate is treated with the solution containing an oxidizing agent for between about 2 days and about 3 weeks.

7. The method of claim 5, wherein the solution containing an oxidizing agent comprises silver ions at a concentration between about 10 ppm and about 200 ppm.

8. The method of claim 7, wherein the silver ions are formed by dissociation of one or more silver salts selected from the group consisting of silver (I) fluoride, silver sulfate, silver sulfite, silver nitrate, silver nitrite, silver acetate and combinations thereof.

9. The method of claim 1, wherein potential reduction sites on the vessel are oxidized so that a final concentration of silver ions in the potable water charged to the vessel is at least about 50% of an initial concentration of silver ions in the potable water after about 15 months.

10. The method of claim 1, wherein the metallic surface comprises an electropositive metal.

11. The method of claim 10, wherein the metallic surface comprises nickel, and wherein at least a majority of exposed nickel on the metallic surface is oxidized to form compounds selected from the group consisting of nickel oxide (NiO₂), nickel carbonate (NiCO₃), nickel hydroxide (Ni(OH)₂) and combinations thereof.

12. A method for preparing a vessel having a metallic surface for long-term storage of potable water containing silver ions, the method comprising:

heating the metallic surface of the vessel to a temperature between about 480°

C. (900°

F.) and about 870°

C. (1600°

F.); and

exposing the metallic surface of the vessel to oxygen during heating to oxidize electropositive metals on the metallic surface.

13. The method of claim 12, wherein the metallic surface of the vessel is exposed to air at a temperature between about 480°

C. (900°

F.) and about 870°

C. (1600°

F.) for a period of time between about 60 minutes and about 4 hours to oxidize electropositive metals on the metallic surface.

14. The method of claim 12, wherein electropositive metals on the vessel are oxidized so that no more than 50% of silver ions in potable water added to the vessel are reduced after about 15 months.

15. The method of claim 12, further comprising:

treating the metallic surface of the vessel with a solution containing an oxidizing agent to further oxidize electropositive metals on the metallic surface.

16. The method of claim 15, wherein the solution containing an oxidizing agent comprises silver ions at a concentration between about 10 ppm and about 200 ppm.

17. The method of claim 12, wherein the metallic surface is selected from the group consisting of metals, metal alloys, stainless steels, corrosion-resistant steels and combinations thereof.

18. A method for preparing a vessel having a metallic surface for long-term storage of potable water containing silver ions, the method comprising:

forming an aqueous solution containing on oxidizing agent; and

treating the metallic surface of the vessel with the aqueous solution containing on oxidizing agent to oxidize potential reduction sites on the metallic surface.

19. A method for controlling silver ion concentrations in water stored in a vessel having a metallic surface, the method comprising:

silver plating a portion of the metallic surface to reduce potential sites for silver reduction on the metallic surface;

filling the vessel with potable water.

20. A vessel for long-term storage of potable water having a metallic surface, wherein the metallic surface of the vessel is oxidized by heating the metallic surface to a temperature between about 480°

C. (900°

F.) and about 870°

C. (1600°

F.) and exposing the metallic surface to oxygen during heating to decrease reduction potential of the metallic surface, and wherein the metallic surface is treated with a solution containing silver ions to further decrease reduction potential of the metallic surface.

21. A vessel for containing potable water comprising silver ions, the vessel comprising:

a metallic surface, wherein a majority of electropositive elemental metals present on the metallic surface are oxidized to prevent reduction of silver ions;

an outlet for discharging potable water from the vessel; and

a filter for preventing microbes from exiting the vessel at the outlet.