DESCRIPTION

Field of the invention

The present invention relates to the technical field of the air conditioning and/or refrigeration systems, and it particularly relates to the use of a solution containing a pH indicator for verifying the suitability of washing an air conditioning and/or HVAC/R refrigeration system as well as a solution containing the pH indicator, a method for preparing the same, a verification device containing such solution and the use of the latter for the verification.

Definitions

In the present document, the expression "% by weight" relating to one or more components in a solution of interest is used to indicate the amount, expressed in grams, of such one or more components with respect to the total grams of the aforementioned solution considered as a whole.

In the present document, the expression "neutralising agent" is used to indicate an agent which, dissolved in a solution, is capable of bringing it to a neutral pH.

State of the Art

The need to clean some components of the HVAC/R systems (that is Heating, Ventilation and Air Conditioning/Refrigeration), relating to the air conditioning, refrigeration and automotive industries both in industrial and civil applications, when installing them or for occasional and/or regular maintenance operations, is known.

The need for such cleaning arises from the presence - in the HVAC/R systems - of contaminants of various types, which may jeopardise the condition and efficiency of some components present in such plants, in particular pipings and heat exchangers, made of different materials, such as copper, aluminium, steel and brass and with inserts and/or rubber gaskets.

Therefore, the refrigeration and/or conditioning system is made suitable for contact with the working fluid, for example the refrigeration and/or air conditioning gas.

As known, the contaminants mainly derive from the oxides of metals forming such components of the system and from the unwanted products of reaction and/or decomposition of the refrigerant gases and of the lubricant oils, generated by the interaction between gas and oil, or between the mixture of the latter with the oxidised metal components of the HVAC/R system.

As a matter of fact, the unwanted impurities that cause the most concern include - as known - the refrigerant gases and lubricant oils reaction and/or decomposition products such as for example halohydric and carbonic acids, stubborn oily residues, moisture/water and the metal-organic salts.

The cleaning, which leads to the removal of such pollutants, is obtained through the through-flow of a washing liquid, typically a solvent, in the components of the system, previously fractionated, to prevent the direct contact of the solvent with the sensitive elements of the HVAC/R systems, the compressor and the dehydrating filter.

After cleaning, the components and the entire HVAC/R system are flushed with anhydrous gas, typically nitrogen, which allows to remove any unwanted residues of the washing liquid used for cleaning.

However, the choice of the amount of washing fluid, as well as the assessment of the cleaning are left to the perception of the operator, thus being extremely subjective and therefore linked to the experience of the latter.

In addition, in order to minimise the risk of permanence of impurities, there is the tendency an excessive use of a washing fluid, which is then difficult to dispose of with resulting high economic and environmental impact.

Furthermore, document JP2OOO2266OO discloses the use of a water-based detergent foam for cleaning evaporators of vehicle air conditioners.

Such foam includes a pH indicator agent and the colour change of the foam indicates the end of the cleaning.

On the other hand, document US9733229 Bl discloses a test kit for verifying the degree of acidity of the lubricant oils of an HVAC system, which includes a test tube containing a solution with a high amount of pH indicator agent, possibly in solid state.

Such kit allows to collect a small oil sample of lubricant oil of the HVAC system to place it in contact with the solution so as to assess the degree of acidity thereof depending on the possible colour change of the test mixture.

Summary of the invention An object of the present invention is to overcome the drawbacks described above by providing a method for verifying the suitability of washing of an air conditioning and/or refrigeration system, that is simple to carry out.

Another object of the present invention is to provide a method for verifying the suitability of washing of an air conditioning and/or refrigeration system that does not require the action of a specialised operators.

Another object of the present invention is to provide a method for verifying the suitability of washing of an air conditioning and/or refrigeration system that minimises the costs of the latter operation.

A further object of the present invention is to provide a method for verifying the suitability of washing of an air conditioning and/or refrigeration system that allows to minimise the amount of washing fluid used.

Another object of the present invention is to provide a method for verifying the suitability of washing of an air conditioning and/or refrigeration system that allows to reduce the times for washing the system.

Another object of the present invention is to provide a method for verifying the suitability of washing of an air conditioning and/or refrigeration system that allows to reduce the volumes of contaminated washing fluid to be dispose of.

Another object of the present invention is to provide a method for verifying the suitability of washing of an air conditioning and/or refrigeration system having a low environmental impact.

A further object of the present invention is to provide a method for verifying the suitability of washing of an air conditioning and/or refrigeration system that allows to minimise the environmental impact of the latter operation.

These and other objects which will be more apparent hereinafter, are attained by a method for using a solution containing a pH indicator for verifying the suitability of an air conditioning and/or refrigeration system as described and/or claimed and/or illustrated herein.

In a further aspect of the invention, these and other objects which will be more apparent hereinafter, are attained by a solution containing a pH indicator for verifying the cleaning of an air conditioning and/or refrigeration system and/or a method for preparing it and/or a first and/or a second intermediate product as described and/or claimed and/or illustrated herein.

In yet a further aspect of the invention, these and other objects which will be more apparent hereinafter, are attained by a solution containing a pH indicator for verifying the cleaning of an air conditioning and/or refrigeration system and/or by the use of the device for verifying the cleaning of an air conditioning and/or refrigeration system as described and/or claimed and/or illustrated herein.

Generally, the verification solution according to the present invention may be used in the context of an HVAC/R system, after washing the latter for example during the installation or maintenance thereof.

According to a preferred but non-exclusive embodiment, such system may belong to the automotive, refrigeration or air conditioning industries, and it may include some components made of metal and possibly elastomeric material.

Specifically, the components particularly intended for washing may be pipings and/or heat exchangers made of copper and/or aluminium and/or steel and/or brass.

In particular, washing using a specific per se known washing fluid may remove the contaminants present in the components, such as for example halohydric and carbonic acids, water, oily residues and metal-organic salts.

Therefore, the verification solution according to the invention may be subsequently used for verifying the full removal of the contaminants mentioned above from the components and therefore guarantee the suitability of the washing carried out, as well as the suitability for the contact of the component washed with the working fluid, for example the air conditioning and/or refrigeration gas.

Therefore, the solution may be adapted to verify the full removal of contaminants, such as for example halohydric or carbonic acids, water, oily residues or metal-organic salts, from the washed component.

For the sake of ease of description, in the description hereinafter the expression 'solution' will be used to indicate the verification solution mentioned above.

Generally, the anhydrous solution according to the invention may contain at least one anhydrous organic solvent (A) and at least one pH indicator agent (D).

In a preferred but non-exclusive embodiment, the solution may further contain at least one additive (B).

Generally, the anhydrous organic solvent (A) may facilitate the dissolution of possible contaminant residues, if still present in the components, so as to facilitate the reaction with the indicator agent (D), therefore increasing the sensitivity of the verification of the suitability of the washing.

Even more particularly, the anhydrous organic solvent (A) may be easily evaporable with the anhydrous gas used for the post cleaning flushing and it may not leave possible residues in the components so as not to subsequently damage the operation of the system.

According to a preferred but non-exclusive embodiment, the anhydrous organic solvent (A) may be an alkane and/or a chlorinated substance.

For example, the alkane may be selected from hexane, heptane, octane and relative isomers.

On the other hand, the chlorinated substance may be selected from trans dichloroethylene, tetrachlorethylene.

Generally, the choice of the organic solvent (A) of the anhydrous type may exclude any water content in the solution.

Suitably, the additive (B) may be an alcohol or a glycol or a mixture thereof.

Suitably, the pH indicator agent (D) may be made particularly stable in the environment defined by the components of the HVAC/R systems mentioned above by the chemical interaction with the additive (B) so as not to distort the suitability test.

Preferably, the final solution may be volatile and with low boiling point, for an easy removal thereof for quick vapourability, for example obtained by flushing an anhydrous gas, for example nitrogen.

Furthermore, the pH indicator may be readily carriable in the organic solvent (A) mentioned above as described below, by interconnecting the additive (B).

For example, the ph indicator may have a colour-change range in a range between 4 - 8.6.

Suitably, the pH indicator may be selected from bromocresol green, 2,5- dinitrophenol, sulphosodium alizarin, methyl red, chlorophenol red, bromocresol purple, p- nitrophenol, bromoxylenol blue, bromothymol blue, bromophenol blue, phenol red, 3- nitrophenol, neutral red or any other pH indicator with colour-change range in a range between 4 - 8.6.

Preferably, the pH indicator agent (D) may be in liquid state.

For example, the solution may include at least one anhydrous organic solvent (A), at least one additive (B) and at least one pH indicator agent (D) from the types listed above.

According to a first preferred but not exclusive embodiment, the anhydrous solution may comprise:

(A) from 83 % by weight to 88 % by weight of the at least one anhydrous organic solvent;

(B) from 10 % by weight to 15% by weight of the at least one additive;

(D) from 0.003 % by weight to 0.005 % by weight of the at least one pH indicator agent.

Specifically, the % by weight of the components (A), (B) and (D) are calculated with respect to the total weight of the solution.

According to a according preferred but not exclusive embodiment, the anhydrous solution mentioned above may consist of:

(A) from 83 % by weight to 88 % by weight of the at least one anhydrous organic solvent;

(B) from 10 % by weight to 15% by weight of the at least one additive;

(C) from 0.001 % by weight to 0.005% by weight of at least one neutralising agent;

(D) from 0.003 % by weight to 0.005 % by weight of the at least one pH indicator agent.

It is clear that the total sum of the % by weight of the components from (A) to (D) is 100%.

Basically, the component (A) may be present at least by 83% by weight with respect to the total weight of the solution, so that the anhydrous solution may consist of:

(A) at least 83% by weight of said at least one anhydrous organic solvent;

(B) from 10 % by weight to 15% by weight of the at least one additive;

(C) from 0.001 % by weight to 0.005% by weight of at least one neutralising agent;

(D) from 0.003 % by weight to 0.005 % by weight of the at least one pH indicator agent.

Clearly, the total sum of the % by weight of the components from (A) to (D) is 100%.

In a third preferred but not exclusive embodiment, the solution mentioned above may consist of:

(A) from 84.99 % by weight to 88 % by weight of the at least one anhydrous organic solvent; (B) from 10 % by weight to 15% by weight of the at least one additive;

(C) from 0.001 % by weight to 0.005% by weight of at least one neutralising agent;

(D) from 0.003 % by weight to 0.005 % by weight of the at least one pH indicator agent.

Also in this case, the total sum of the % by weight of the components from (A) to (D) is 100%.

As a result, the solution may contain a neutralising agent (C) capable of bringing it to neutral pH.

In a fourth preferred but non-exclusive embodiment, the solution of the second and third embodiment may have a single neutralising agent (C) and a single pH indicator (D) so as to reduce the costs and difficulty in preparing the solution.

Preferably, the neutralising agent (C) may be anhydrous sodium hydroxide.

However, it is clear that the neutralising agent (C) may be selected from anhydrous sodium hydroxide, anhydrous potassium hydroxide, highly volatile amines without departing from the scope of protection of the attached claims.

Generally, the fact that the solvent (A) is of the anhydrous type and the bond between the additive (B) and the pH indicator agent (D) occurs without using water and through hydrogen bonds, the solution may be completely without water, with the resulting almost zero moisture content in the components and in the entire HVAC/R system.

Therefore, it is clear that the suitability of the washing of the components of interest may be assessed using the same solution in the washed component and the colour of the solution flowing out from the latter may be assessed visually after flowing through it, without any interference whatsoever.

Specifically, upon the exit of the component, should the solution have a different colour with respect to its colour when the component was introduced, this will indicate the presence of contaminants in the latter and therefore the need for further washing with the washing fluid to improve the cleaning and make it suitable for contact with the working fluid.

As a result, the suitability test of the washing will be extremely objective and easy to assess for anyone or an operator who is not particularly specialised.

It is clear that this will allow to use a minimum initial amount of washing fluid, calculated based on the size of the component to be washed in a per se known manner, and possibly carry out the washing again with a further minimum amount if the test reveals the presence of contaminants.

As a matter of fact, in this manner the amount of fluid used in the washing and then to be dispose of, will be extremely optimised.

In particular, the solution may be in liquid form and therefore it may be made to flow through the washed component.

Specifically, compressed air or an anhydrous gas pushed through special lances or guns may be used in a per se known manner, so as to make the solution flow through the washed component.

Typically, the use of the anhydrous solution in liquid form may be particularly useful in large components, for example of a refrigeration system.

However, it is clear that the liquid formulation may also be used in the automotive or air conditioning industry without departing from the scope of protection of the attached claims.

On the other hand, the solution may be in aerosol or atomised form and therefore it may be made to flow through by flushing in the washed component.

In particular, the aerosol or atomised formulation may be advantageous for small components, typically such as for example the components of an air conditioning or automotive system.

However, it is clear that the formulation of the aerosol or atomised solution may also be used in refrigeration systems or the like without departing from the scope of protection of the attached claims.

A further aspect of the invention may relate to a device for verifying the suitability of washing of one or more components of an HVAC/R system, in particular in the automotive, refrigeration and air conditioning industries, following the installation and/or maintenance thereof which may comprise an anhydrous solution as described above, a container for containing it and means for promoting the flow of the solution through the washed component.

In a first embodiment, the solution may be in liquid form and the means for promoting the flow may comprise a unit for supplying a pressurised propellant fluid.

In this case, the solution may be contained in a special per se known container, for example a jerrican, and it may be poured into the washed component for the verification test. Subsequently, the propellant fluid may push the solution in the component. For example, the propellant fluid may be compressed air and the means for promoting the flow may be in the form of a compressor provided with special lances or guns.

In this case, after pouring the liquid solution into the component of the washed system, the lance of the compressor may be positioned at an end of the component so that the compressed air can push the solution in the component towards the opposite end to allow the exit thereof.

In a second embodiment, shown in FIG.l, the device 1 may include the aforementioned container, identified with 10, which may be of the pressurised type, and it may include an internal chamber 10' containing the solution.

Alternatively, the container may be pressurizable, for example by means of an external propellant fluid or a hand pump.

In this case, as particularly shown in FIG.2, the means for promoting the flow may comprise at least one propellant fluid adapted to pressurise the container 10, a supply nozzle 11 connected or which can be connected with the container 10, a fluidic connection line 12 extending between the internal chamber 10' and the nozzle 11 and valve means 13.

The latter may be arranged along the fluidic connection line 12 so as to allow or vice versa selectively prevent the inflow of the solution to the supply nozzle 11.

Advantageously, the valve means 13 may be normally closed and the opening thereof may allow the inflow of the solution into the supply nozzle 11.

Preferably, the supply nozzle 11 may be a conical nozzle so as to allow an easy positioning thereof at an end E' of the component C so as to allow the introduction of the solution, as shown in FIG. 1.

Such nozzle 11 may rest on a special base 11' so that pressing the nozzle 11 by the operator may allow the actuation of the valve means 13, for example by moving a stem 14, for dispensing the solution, in a per se known manner.

In a preferred but non-exclusive embodiment, the propellant fluid may be anhydrous.

Preferably, the pressure inside the chamber 10' may be between 2 bar and 6 bar and advantageously between 3 and 5 bar.

Suitably, the propellant fluid may be a mixture of LPG and nitrogen or a mixture of propane and butane or isobutane or even a mixture of nitrogen, propan e and butane or isobutane or the like.

Preferably, the fluidic connection line 12 may be without a flexible hose interposed between the container 10 and the nozzle 11. In other words, the nozzle 11 may be suitable to be positioned directly at the inlet of the component C to be tested, as shown in FIG. 1.

In a preferred but non-exclusive embodiment, the container 10 may be of the disposable type, so as to make the verification extremely simple and practical to be carried out.

Therefore, once through with the flushing, the operator may dispose of the container 10, nozzle 11 used in the verification operation.

For example, the container 10 may be a disposable spray can, of the per se known type.

The use of the device 1 of the second embodiment to verify the washing may occur by connecting the supply nozzle 11 with the washed component C of the HVAC/R system and subsequent actuation of the valve means 13 by an operator so as to allow the flushing of the solution in the component C, from the end E' to the end E" of the component C for the outflow of the solution, as particularly observable in FIG.l.

In the case of a spray can, the operator may therefore actuate the valve means 13 by pressing the supply nozzle 11, so as to release the solution in atomised form by the nozzle 11 in a per se known manner.

Once through with the flushing, the operator will therefore dispose of the can provided with nozzle and will evaluate the colour of the outflowing fluid to verify the possible colour change of the solution so as to carry out the verification test.

According to a further aspect of the invention, there may be provided for a method for preparing the anhydrous solution mentioned above.

First and foremost, the pH indicator agent (D) may be dissolved in one or more additives (B) so as to obtain a first intermediate product.

In particular, the pH indicator agent (D) may be chemically bonded to the one or more additives (B) through hydrogen bonds, so as to form a first intermediate product.

Subsequently, the one or more additives (B) may carry in solution the indicator (D) in the anhydrous organic solvent (A), thanks to the chemical affinity present between the latter and the former (B).

In this manner, the solution will be entirely without water, therefore not reacting with the component or contaminants of the HVAC/R system.

The first intermediate product obtained may therefore be added to the anhydrous organic solvent (A) and it will melt in the latter thanks to the optimal mixability of the one or more additives (B), allowed by the high chemical affinity between the solvent (A) and the latter (B).

This may allow to obtain a second intermediate product which may be neutralised by adding the one or more neutralising agents (C) so as to bring the obtained solution to neutral pH.

It is clear that the neutralisation may also occur on the first intermediate product, or both on the first and on the second intermediate product, without departing from the scope of protection of the attached claims.

Basically, the final solution shall have the desired final colour, or the one that the preselected pH indicator (D) has under conditions the closest possible to neutrality.

Therefore, the addition of the neutralising agent (C) may be closely correlated to achieving such condition.

It is clear that the intermediate products described above may be intended to prepare the anhydrous solution as described.

Therefore, it is clear that both with reference to the preparation method mentioned above and with reference to the intermediate products, the components may be present in the amounts described above.

Therefore, the amounts may be from 83 % by weight to 88 % by weight of the solution or at least 83% by weight of the solution of the at least one anhydrous organic solvent (A), from 10 % by weight to 15% by weight of the solution of the at least one additive (B), from 0.001 % by weight to 0.005% by weight of the solution of the at least one neutralising agent (C), where present, from 0.003 % by weight to 0.005 % by weight of the at least one pH indicator agent (D).

The invention will be described in greater detail with reference to the following examples which, in any case, shall not be deemed to limit the scope of protection of the invention.

Examples

Example 1 - preparation of samples

Twenty-six samples of the verification solution in liquid form with a first organic solvent (SAMPLE 1 - 13) and a second organic solvent (SAMPLE 14 - 26) were prepared.

The samples SAMPLE 1 - 13 consisted of: (A) 87.4948% by weight of Heptane;

(Bl) 10% by weight of glycol;

(B2) 2.5% by weight of butanol;

(C) 0.001 % by weight of anhydrous sodium hydroxide;

(D) 0.0042 % by weight of a pH indicator agent as shown in table 1 below.

The samples SAMPLE 14- 26 consisted of:

(A) 87.4948% by weight of Tetrachlorethylene;

(Bl) 10% by weight of glycol;

(B2) 2.5% by weight of butanol;

(C) 0.001 % by weight of anhydrous sodium hydroxide;

(D) 0.0042 % by weight of a pH indicator agent as shown in table 1 below.

In particular, the indicator (D) was dissolved in the additive (B2). The obtained mixture was then dissolved in the additive (Bl) and the entirety was then added to the solvent (A). TABLE 1

Example 2 - Stability analysis of the pH indicator

A test was carried out to assess the stability of the pH indicators in Table 1, by introducing samples SAMPLE 1 to 26 into a 1 cm diameter and 600 cm length copper pipe of an HVAC system after washing it with a washing solution consisting of Heptane and subsequent introduction of contaminants into the latter.

The stability of the indicator was defined by visual evaluation of the coloring of the solution at the inlet and outlet of the piping when collected in a clean specific collector.

In particular, in the case of colour change, the indicator was defined as suitable for the verification test and, vice versa, not suitable for the verification test.

The results are reported in table 2:

TABLE 2

From the data provided, it can be said that the pH indicators present in the samples SAMPLE 1 - 26 were all suitable because they changed the colour and therefore indicated the presence of contaminants in the piping. Therefore, generally, samples with pH indicators with a colour-change range between 4 and 8.6 were considered suitable for testing the suitability of an HVAC/R system or a component of an HVAC/R system.