CORROSION INHIBITOR FOR A CENTRAL HEATING SYSTEM

Abstract

A corrosion inhibitor for a central heating system is provided in the form of a cream having low water content, which may be encapsulated within a water-soluble film, for example a poly (vinyl alcohol) film. The corrosion inhibitor product is more highly-concentrated than known liquid inhibitors, and the encapsulation in a water soluble film provides for safer handling and eliminates waste from plastic packaging.

Claims

1-25. (canceled)

26. A method of manufacturing a corrosion inhibitor product for a central heating system, the corrosion inhibitor including a plurality of ingredients, the plurality of ingredients including both organic and inorganic compounds, and the method comprising the steps of: (a) dividing the ingredients into groups, including at least a first group of ingredients all of which are water soluble, and a second group of ingredients all of which are soluble in an organic solvent which is miscible in water; (b) dissolving the ingredients of the first group in water to make a first solution; (c) separately dissolving the second group of ingredients in the organic solvent to make a second solution; (d) mixing together the first solution and the second solution.

27. The method as claimed in claim 26, in which the ingredients of the first group include one or both of sodium molybdate and sodium gluconate.

28. The method as claimed in claim 26, in which the ingredients of the second group include benzotriazole.

29. The method as claimed in claim 26, in which the ingredients of the second group include at least one amine.

30. The method as claimed in claim 26, in which the organic solvent is an amine which is miscible in water.

31. The method as claimed in claim 26, in which the ingredients of the second group include glycol.

32. The method as claimed in claim 26, further comprising the step of: (e) encapsulating the mixture of the first solution and the second solution in a water-soluble film.

33. The method as claimed in claim 32, in which the water-soluble film is poly (vinyl alcohol).

34. The method as claimed in claim 26, in which the first solution is produced at a temperature of at least 40 or 45° C. or at least 50° C.

35. The method as claimed in claim 26, in which the second solution is produced at a temperature of at least 40 or 45° C. or at a temperature of at least 50 degrees.

36. The method as claimed in claim 32, in which the mixture of the first solution and the second solution is cooled before encapsulating the mixture in the film.

37. The method as claimed in claim 26, in which mixing the solutions in step (d) forms a homogenous product containing 20% or less water content by volume.

38. A corrosion inhibitor product for use in protecting a central heating system, the corrosion inhibitor product comprising: a homogenous cream which includes: at least 30% or 35% amine by volume; at least 5% sodium molybdate by volume; at least 5% sodium gluconate by volume; less than 20% water by volume, the homogenous cream being encapsulated in a water-soluble film or provided in a container.

39. The corrosion inhibitor product as claimed in claim 38, in which the water-soluble film is a polymer film or a poly (vinyl alcohol) film.

40. The corrosion inhibitor product as claimed in claim 38, which contains at least 40% amine by volume.

41. The corrosion inhibitor product as claimed in claim 38, which contains one or both of: at least 10% sodium molybdate by volume, and at least 10% sodium gluconate by volume.

42. The corrosion inhibitor product as claimed in claim 38, which contains at most 20% water by volume.

43. A method of protecting a central heating system from corrosion, the method comprising introducing a corrosion inhibitor product according to claim 38 into the central heating system fluid.

44. The method of protecting a central heating system as claimed in claim 43, in which the corrosion inhibitor product is introduced into the system via a dosing pot.

45. The method of protecting a central heating system as claimed in claim 44, in which the dosing pot is a magnetic filter.

Description

DESCRIPTION OF THE DRAWINGS

[0054] For a better understanding of the invention, and to show more clearly how it may be carried into effect, specific embodiments will now be described with reference to the accompanying drawings in which:

[0055] FIG. 1 is a flow chart illustrating the method of the first aspect of the invention; and

[0056] FIG. 2 shows a corrosion inhibitor product according to the second aspect of the invention being used to protect a central heating system according to the method of the third aspect of the invention.

DESCRIPTION OF THE EMBODIMENTS

[0057] The process of making a corrosion inhibitor product suitable for use in protecting a central heating system is briefly set out in the flow chart in FIG. 1.

[0058] In step 10 a first solution is made by dissolving water soluble ingredients in water. The water-soluble ingredients may include sodium molybdate and sodium gluconate. The first solution may contain around 40% - 50% water by volume, with the remainder being mostly sodium molybdate and sodium gluconate in about equal measure. In some embodiments further water-soluble components may also be included. The water is heated to at least about 50° C. to ensure complete dissolution of the water-soluble ingredients.

[0059] In step 12 a second solution is made by dissolving non-water-soluble ingredients in an organic solvent. The solvent may be an amine which as well as acting as a solvent also works as an inhibitor. Benzotriazole, various amines, and glycol are examples of ingredients which may be mixed together to form the second solution. Again, the solvent(s) are preferably heated to around 50° C. or more to ensure complete dissolution.

[0060] In step 14 the first solution and the second solution are combined. This is done quickly to ensure complete mixing to form a homogenous product. It is found that when the first and second solution are combined, a stiff aqueous cream is quickly formed. This is a stable product which can be allowed to cool (step 16) and stored at room temperature.

[0061] At step 18 a dose of cream is encapsulated in a water-soluble film. The film may be for example made from poly (vinyl alcohol). Encapsulating creams in soluble films is known, for example, for creating “pouches” containing laundry detergent. The cream created by steps 10, 12 and 14 has sufficiently low water content that it can be encapsulated in such films, which is so far unknown for a central heating corrosion inhibitor. In other embodiments, one or multiples doses of cream may be provided in a tube or other container.

[0062] The cream may be sufficiently concentrated that a typical domestic heating system may require a dose of around 200 ml. It is envisaged that a “pouch” could be made containing about 50 ml, so that dosing a heating system could use for example four tablets. Alternatively, smaller pouches could be made to reasonably accurately correspond with the amount of inhibitor needed to dose one radiator, or radiators heating one room. This allows for very easy estimation of the correct amount with which to dose a central heating system. For example, a good approximation of the dose required might be around 30 ml multiplied by the number of radiators in the system. If the inhibitor is provided in 30 ml pouches, then a heating engineer simply needs to count the number of radiators and dose the system with that number of tablets. This may provide a much more accurate way of estimating the correct dose than with existing liquids, which are often provided in bottles of around 300 ml which are supposed to be suitable for a “typical domestic system”. “Typical domestic systems” in fact vary in size quite a lot, wasting chemical in smaller systems and potentially under-dosing larger systems. By providing the chemical in small dose pouches, this problem is avoided.

[0063] It will be appreciated that larger, perhaps much larger, pouches may be produced to suit larger central heating systems.

[0064] A pouch of around 30ml may also be easily introduced into a dosing pot or magnetic filter. FIG. 2 shows the Adey MagnaClean (RTM) Professional 2 filter with the lid removed. The filter is indicated generally at 100. The filter is isolated from the flow and return of the central heating circuit by closing valves 120, and then the lid (not shown) is removed. The magnet is also removed, which will leave some space in the canister, i.e. the canister will not be completely full of water. At this point a pouch 130 made according to the process of FIG. 1 may be introduced. The water-soluble film will dissolve, releasing the inhibitor chemical into the central heating system water.

[0065] Where a tube or other container is used in other embodiments, the cream may be squeezed or sprayed or otherwise dispensed from the container and introduced into the central heating system water. It will then become distributed or dispersed in the central heating system water.

[0066] The corrosion inhibitor product of the invention allows for desired amounts of inhibitor chemicals to be formulated together in a product which has a significantly lower amount of solvent, particularly water, and thus a significantly higher relative concentration of inhibitor chemicals compared to prior art formulations. The amounts of inhibitor chemicals or ingredients can be varied as needed, subject to being suitably dissolvable in the amounts of the respective solvents used.

[0067] The corrosion inhibitor pouches of the invention provide for a corrosion inhibitor which generates less plastic waste, is safer to handle, and is smaller and lighter making it more efficient to store and transport. Doses can be more accurately estimated to make the best use of the chemical to protect different sized heating systems.