A SURFACE CONTAMINATION TESTING DEVICE AND TECHNIQUE USING ULTRASOUND FOR REMOVAL OF CONTAMINANTS FROM A SURFACE

The present invention relates to surface contamination test ^¬ ing techniques, and more particularly to surface contamina ^¬ tion testing techniques that use ultrasound. Natural salts, especially chloride anion containing salts, are known to be corrosive to many materials, including met ^¬ als, polymers and composite structures which are extensively used in modern day equipment employed in industries e.g. pow ^¬ er generation plants. For example, wind turbine blades are manufactured using different polymers and other composite ma ^¬ terial. Usually a protective coating is applied on surfaces of such equipment, such as on a surface of a wind turbine blade to safeguard the structural integrity of the surface. However, before application of the coating it is crucial, for long service-life of the substrate i.e. the surface of the equipment on which the coating is applied as well as for good adherence of the coating that the substrate surface is free from such natural salts. If such precaution is not taken the salts, i.e. the contaminants, are trapped or captured on the surface beneath the coating and cause premature failure of both the substrate material and, possibly, also the coating. As a consequence, the whole system i.e. the substrate and the protective coating, will fail and require repair or even re ^¬ placement, which is a costly, cumbersome and labor intensive procedure.

Only in incidents with severe surface contamination, i.e. presence of large quantities of the contaminants, is it pos ^¬ sible to visually inspect the substrate surface to conclude the presence of contaminants, however chloride-induced corro ^¬ sion, and also from similar other contaminants, can be an issue even in small amounts (ion concentrations) down to PPM (parts-per-million) if present on the substrate surface. Presently, some conventional methods are used to evaluate presence and possibly the amount of contaminants on the sur ^¬ face of the substrate. One commonly used method is the Bresle method that uses Bresle sampler in shape of a patch that is configured to be adhered to the surface to be tested. The patch has a cavity of known dimension and volume. Distilled or deionized water is injected into the cavity by syringe needle through a rubbery film. After one minute of contact the water is removed using a syringe needle. The water so re ^¬ moved is analyzed by chemical reagents for its chloride con ^¬ tent using different reagents. Although Bresle method is use ^¬ ful for removing readily extracted chlorides from the surface of the substrate not all chlorides are removed from corroded and pitted surfaces by simply water washing the surfaces as is done in the Bresle method. Therefore this method does not account for the actual amount of contaminants present on the surface of the substrate. Also, the adhered patch leaves be ^¬ hind sticky adhesive, which is also detrimental to adhesion of the subsequently applied coating or protective layer. Fur ^¬ thermore, in some cases, the patch cannot be readily

peeled/released from the surface for e.g. the patch while be ^¬ ing removed may tear off some paint types from the substrate surface .

There are also other similar conventional methods of surface contamination testing that employ washing the surface with water which then is collected and analyzed by different chem ^¬ ical and electrochemical processes. All such conventional methods suffer from the same problem of inadequate removal of the contaminants from the surface of the substrate. Moreover, removal of the water after exposure to the surface requires manual intervention. Furthermore, some conventional tech ^¬ niques require collection of the water after exposure to the surface to be tested and then transportation of the collected samples for testing in laboratory. Thus there exists a need for a technique that obviates or re ^¬ duces the aforementioned drawback of inadequate removal of the contaminants from the surface of the substrate. An object of the present invention is to provide a technique that ensures enhanced removal of the contaminants from the surface of the substrate vis-a-vis removal of the contami ^¬ nants from the surface of the substrate achieved from simply washing the surface with water. Furthermore the technique is desired to be such that it reduces the requirement of manual intervention and the need for transporting the collected samples for testing in laboratory.

The above object is achieved by a surface contamination test- ing device according to claim 1 of the present technique and a surface contamination testing method according to claim 10 of the present technique. Advantageous embodiments of the present technique are provided in dependent claims. In a first aspect of the present technique, a surface contam ^¬ ination testing device for determining contaminants on a surface is presented. The surface may be, but not limited to, a surface on a tower or blade of a wind turbine that is desired to be coated with a protective layer/coating. The soluble contaminants may be, but not limited to, soluble salts such as Sodium chloride, Calcium chloride, Potassium nitrate, etc. The device has a housing having a suction cup, a vacuum pump, a solvent supply, an ultrasound generator, a sensor arrange ^¬ ment and a readout mechanism. The vacuum pump, the solvent supply, the ultrasound generator, and/or the sensor arrange ^¬ ment are housed within the housing whereas the readout mecha ^¬ nism may be integrated into the housing surface so as to be perceptible by an observer. The suction cup extends outward from the housing such that the suction cup may be positioned on the surface to be tested. The suction cup when positioned on the surface defines a volume contiguous with the surface i.e. the surface to be tested and inner wall of the suction cup enclose a space that acts as the volume. The vacuum pump is operable to create at least a partial vacuum within the volume. The creation of the vacuum is supported by the suc ^¬ tion cup, the surface to be tested and the housing. The vacu ^¬ um pump may be operable manually or electronically. The sol- vent supply provides a solvent, for example deionized water, to the volume such that the solvent collects in the volume and is contiguous with the surface. The flow of the solvent may be achieved by active pumping of the solvent into the volume from the solvent supply, such as a reservoir for the solvent, or may be achieved by flow of the solvent from the solvent supply into the volume under the negative pressure of the volume resulting from the vacuum created in the volume by action of the vacuum pump. A valve with release mechanism may be installed in the solvent supply to regulate the flow rate and/or amount of the solvent provided into the volume.

The ultrasound generator is a transducer that generates ul ^¬ trasound waves within the solvent collected in the volume. The ultrasound waves facilitate the dissolution of the con- taminants, if any, from the surface and into the solvent col ^¬ lected in the volume. The solvent collected within the volume is subjected to the ultrasound waves for a predetermined pe ^¬ riod of time. After completion of the aforementioned action, the solvent with the dissolved contaminants, if any, is sub- jected to the sensor arrangement. The sensor arrangement may comprise sensing component to sense a characteristic of the solvent and a microcontroller to analyze the sensed charac ^¬ teristic and derive or determine an amount of contaminant present in the solvent which in turn indicates an amount of contaminant that is present on the surface that was tested.

An indication of the amount of the contaminants so determined is then provided by the readout mechanism, for example a dig ^¬ ital display, for the observer or test engineer to read. The surface contamination testing device has the advantage of in- creased sensitivity based on achievement of enhanced release of the contaminants into the solvent under the effect of the ultrasound. The contaminants that would have generally re ^¬ mained undetached from the surface would detach as a result of the ultrasound emitted from the surface contamination testing device, thus enhancing the efficacy of the surface contamination testing. In an embodiment of the surface contamination testing device, the sensor is a conductivity meter. Such sensors are small in size and readily available, thus making the device compact, easy to manufacture and cost effective. In another embodiment of the surface contamination testing device, the suction cup includes the ultrasound generator. Thus the ultrasound generator, i.e. an ultrasound transducer embedded in the suction cup is safeguarded against contact with the solvent, and thus ensuring that the solvent does not damage the components of the ultrasound transducer. Moreover, the ultrasound generator is also protected from external wear and tear by virtue of the ultrasound generator being embedded in the material of the suction cup which acts as a protective coating for the ultrasound transducer.

In another embodiment of the surface contamination testing device, the ultrasound generator is positioned within the housing and is extendable into the volume from within the housing. This provides the flexibility in positioning of the ultrasound transducer relative to the surface that is to be tested, i.e. the ultrasound generator can be positioned clos ^¬ er to the surface or farther from the surface, thus providing a control on the impact of the ultrasound waves on the sur ^¬ face to be tested.

In another embodiment of the surface contamination testing device, the vacuum pump is manually operable. Thus need for motorizing or automating the vacuuming is obviated, which in turn makes the device simpler and more cost effective.

In another embodiment of the surface contamination testing device, the vacuum pump is electronically operable, i.e. a motorized mechanism is placed in the surface contamination testing device for operating the vacuum pump. Thus the degree and/or rate of vacuum creation can be pre-set or precisely controlled, and require little or no human intervention in vacuum pump operation.

In another embodiment of the surface contamination testing device, the ultrasound generator is configured to produce ul ^¬ trasound waves having a frequency between 30 kHz and 150 kHz. This presents a range for achieving dissolution of a wide range of the contaminants into the solvent by the action of the ultrasound.

In another embodiment, the surface contamination testing device has a portable form. Thus the device can be moved easily to the place of testing, for example to a wind farm where surface of a wind turbine is desired to be tested.

In another embodiment, the surface contamination testing device has a hand-held form. Thus the device is easy to carry and handle.

In a second aspect of the present technique, a surface con ^¬ tamination testing method for determining contaminants on a surface is presented. The method may use a surface contamina- tion testing device in accordance with the aforementioned first aspect of the present technique. In the method, first a suction cup is positioned on the surface to be tested. The suction cup when positioned on the surface defines a volume contiguous with the surface. Then, at least a partial vacuum is created in the volume by using a vacuum pump. The vacuum pump may be manually or electronically operated. Subsequently to or simultaneously with creation of the vacuum, a solvent, for example deionized water, is provided into the volume such that the solvent collects in the volume and is contiguous with the surface to be tested. The flow of the solvent may be achieved by active pumping of the solvent into the volume from a solvent supply, such as a reservoir for the solvent in the surface contamination testing device, or may be achieved by flow of the solvent from the solvent supply into the vol ^¬ ume under the negative pressure of the volume resulting from the vacuum created in the volume by action of the vacuum pump. The flow rate and/or amount of the solvent provided into the volume may be regulated by a valve associated with the solvent supply, the valve having a release mechanism and installed in the solvent supply. Thereafter, ultrasound waves are generated for a predetermined time period within the sol ^¬ vent collected in the volume. The ultrasound waves generated may have frequency between 30 kHz and 150 kHz.

After the aforementioned step of generating the ultrasound, the solvent is provided, after the predetermined time period, to a sensor arrangement configured to detect an electrical property of the solvent, such as electrical conductivity of the solvent. Finally, an amount of the contaminants present on the surface is determined, from the electrical property so detected. The surface contamination testing method has the advantage of increased sensitivity based on achievement of enhanced release of the contaminants into the solvent under the effect of the ultrasound. The contaminants that would have generally remained undetached from the surface would de ^¬ tach as a result of use of the ultrasound in the surface con ^¬ tamination testing method, thus enhancing the efficacy of the surface contamination testing. Optionally, in the method an indication of the amount of the contaminants so determined may be then provided to an observer or test engineer to read via a readout mechanism, for example a digital display of the aforementioned surface contamination testing device.

The present technique is further described hereinafter with reference to illustrated embodiments shown in the accompany ^¬ ing drawing, in which: FIG 1 schematically represents an exemplary embodiment of a surface contamination testing device of the pre ^¬ sent technique, schematically represents an exemplary embodiment of an initial stage of working of the surface contami ^¬ nation testing device wherein the device is posi ^¬ tioned on a surface to be tested, schematically represents an exemplary embodiment of a next step of working of the surface contamination testing device after the initial stage depicted in FIG 2, schematically represents an exemplary embodiment of a further step of working of the surface contamina ^¬ tion testing device after the step depicted in FIG 3, schematically represents an exemplary embodiment of yet another step of working of the surface contamination testing device after the step depicted in FIG 5 and wherein ultrasound is generated, schematically represents an exemplary embodiment of an effect of the ultrasound generated in FIG 5, schematically represents an exemplary embodiment of a subsequent stage, compared to FIG 6, in the work ^¬ ing of the device wherein measurement of an amount of contaminants is performed, depicts a flow chart representing an exemplary em- bodiment of a surface contamination testing method of the present technique, schematically represents an exemplary embodiment a suction cup of the device of the present tech ^¬ nique, FIG 10 schematically represents an exemplary embodiment of an ultrasound generator extended into the suction cup of FIG 9, and FIG 11 schematically represents another exemplary embodi ^¬ ment of the ultrasound generator embedded in the suction cup; in accordance with aspects of the pre ^¬ sent technique. Hereinafter, above-mentioned and other features of the pre ^¬ sent technique are described in details. Various embodiments are described with reference to the drawing, wherein like reference numerals are used to refer to like elements

throughout. In the following description, for purpose of ex- planation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodi ^¬ ments. It may be noted that the illustrated embodiments are intended to explain, and not to limit the invention. It may be evident that such embodiments may be practiced without these specific details.

The present technique presents a surface contamination test ^¬ ing device 1, hereinafter also referred to as the device 1 and a surface contamination testing method 100, hereinafter also referred to as the method 100. FIGs 1 to 7 are used hereinafter to explain an exemplary embodiment of the device 1 and different stages of use of the device 1, and FIG 8 rep ^¬ resents the method 100 that may be implemented using the de ^¬ vice 1.

FIG 1 shows the device 1. The device 1 is used for carrying out surface contamination testing on a surface 9 of a sub ^¬ strate or element 90. The phrase 'surface contamination test ^¬ ing' as used herein means determining a presence or absence of one or more contaminants such as a salt, chloride ion, etc on a surface of a substrate, and optionally determining an amount i.e. a concentration of the contaminants on the sur ^¬ face. The surface 9 may be, but not limited to, a surface 9 on a tower 90 or blade 90 of a wind turbine that is desired to be coated with a protective layer/coating. The contaminants 99 may be, but not limited to, soluble salts such as Sodium chloride, Calcium chloride, Potassium nitrate, etc. For example FIGs 1 to 7 schematically depict en element 90 that may be, a wind turbine blade, having a surface 9 that is desired to be tested for the contaminants 99, which are shown to be present on the surface 9 of FIG 1. The device 1 has a housing 10 having a suction cup 12, a vac ^¬ uum pump 20, a solvent supply 30, an ultrasound generator 40, a sensor arrangement 50 and a readout mechanism 60. The hous ^¬ ing 10 is generally made of plastic or a similar polymeric material. The vacuum pump 20, the solvent supply 30, the ul- trasound generator 40, and the sensor arrangement 50 are housed or placed within the housing 10. The solvent supply 30 is a compartment or chamber within the housing 10. The compartment is fillable, i.e. is able to be filled, with a sol ^¬ vent 5 through a filling port 32 which opens at a surface of the housing. The solvent 5 may be, but not limited to dis ^¬ tilled or deionized water or any other liquid that acts as a solvent for the contaminants 99 that are suspected to be pre ^¬ sent or generally known to be present on the surface 9 of the element 90. The filling port 32 through which the solvent 5 is filled into the device 1 before an intended use of the de ^¬ vice 1, and particularly filled into the solvent supply com ^¬ partment of the device 1, may be provided with a cap or lid that can be screwed or fitted onto the filling port 32 to avoid spillage of the solvent 5 outside of the device 1 or onto an external surface of the housing 10 when the solvent 5 is filled and contained in the solvent supply 1.

The vacuum pump 20 may be an electronically operable or a manually operable vacuum pump 20 and operates to suck out air, for example with a syringe like action based on a mova ^¬ ble piston. The vacuum pump 20 may be housed entirely within the housing 10 when the vacuum pump 20 is electronic, and may have associated vacuuming mechanism having electronically op- erated pumps, motors, valves etc. A switch (not shown) of the electronically operable vacuum pump 20 may be positioned on the housing 10 and be accessible to a user to switch on and off and to initiate vacuuming action. The electronically op- erable vacuum pump 20 may require electrical power which can be provided to the vacuum pump 20 by connecting the vacuum pump 20, i.e. the device 1 to an external power source, for example an electrical socket. Alternatively, the housing 10 may include therein a battery to power the electronically op- erable vacuum pump 20. The vacuum pump 20 when manually operable may be housed partly within the housing 10 and partly outside the housing 10 as an extension from the housing 10, for example a piston (not shown) and/or a valve (now shown) of the vacuum pump 20 may be positioned inside the housing 10, whereas a trigger handle (not shown) of the manually op ^¬ erable vacuum pump 20 may extend outside of the housing 10. The user of the device 1 may press and release the trigger once or multiple times to effect the plunger action of the vacuum pump 20 to create the desired vacuum.

As shown in FIG 1, the suction cup 12 extends outward from the housing 10 such that the suction cup 12 may be positioned on the surface 9 to be tested when the user desires to initi ^¬ ate the surface contamination testing. FIG 2 depicts working of the device 1 wherein the suction cup 12 has been posi ^¬ tioned on the surface 9, or more precisely on a part or re ^¬ gion of the surface 9. The suction cup 12 when positioned on the surface 9 defines a volume 7 contiguous with the surface 9 i.e. the surface 9 to be tested and inner wall of the suc- tion cup 12 enclose a space that acts as the volume 7. The suction cup 12 has an opening 13 (shown in FIG 1), also known as a working face of the suction cup 12, and is made of elas ^¬ tic, flexible material and generally has a curved surface. When the opening 13 of the suction cup 12 is pressed against the surface 9, the suction cup 12 adheres to the surface 9, and forms a fluid-tight sealing. The volume 7 as shown in FIG 2 is formed by the part of the surface 9 covered under the opening 13 of the suction cup 12, the inside of the suction cup 12 and optionally an inside of the housing 10. FIG 2 rep ^¬ resents schematically, a step of the method 100 of FIG 8 i.e. positioning 110 of the suction cup 12 on the surface 9 that is to be tested.

As shown in FIG 2, the vacuum pump 20 is operated, after the step 110, to create at least a partial vacuum within the vol ^¬ ume 7 which is the step 120 in the method 100 of FIG 8. The creation and maintenance of the vacuum is supported by the suction cup 12, the surface 9 to be tested and the housing 10.

FIG 3 depicts a step 130 of the method 100 of FIG 8. In the step 130, and as schematically depicted in FIG 3 representing working of the device 1, the solvent 5 is provided into the volume 7. The solvent 5 so supplied to the volume 7 is pro ^¬ vided from the solvent supply 30. Flow of the solvent 5 from the solvent supply 30 and into the volume 7 may be achieved by active pumping of the solvent 5 or may be achieved by flow of the solvent 5 under the negative pressure of the volume 7 resulting from the vacuum created in the volume 7 by action of the vacuum pump 20. A valve (not shown) with release mechanism may be installed in the solvent supply 30 to regulate the flow rate and/or amount of the solvent 5 provided into the volume 7. The solvent 5 collects in the volume 7. The solvent 5 is contiguous with, i.e. is in direct physical con ^¬ tact with the surface 9, or more particularly with the part of the surface 9 that is covered under the opening 13 of the suction cup 12.

FIGs 4 and 5 schematically depict a step 140 of the method 100 of FIG 8. In the step 140, the ultrasound generator 40 of the device 1 is a transducer that generates ultrasound 42 i.e. ultrasound waves 42, generally having a frequency be- tween 30 kHz and 150 kHz, and within the solvent 5 collected in the volume 7. FIG 4 depicts an exemplary positioning of the ultrasound transducer 40, without depicting the ultra ^¬ sound waves 42. The ultrasound generator 40, also referred to as the ultrasound transducer 40, may be fixed in position as shown in FIG 4 or may be extendable to a desired position form within the housing 10 as can be understood by a comparison of FIG 3 and FIG 4 with respect to relative positioning of the ultrasound transducer 40 within the housing 10. FIG 9 shows only the suction cup 12 and relative positioning of the ultrasound transducer 40, whereas FIG 10 shows a changed po ^¬ sitioning of the ultrasound transducer 40 wherein the ultra ^¬ sound transducer 40 is extended from an inside of the housing 10 (not shown in FIGs 9 and 10) and into the volume 7. Alter ^¬ natively as shown in FIG 11, in the device 1 the ultrasound transducer 40 may be manufactured as embedded in the suction cup 12. FIG 5 shows generation 140 of the ultrasound waves 42 from the ultrasound transducer 40. The ultrasound waves 42, here ^¬ inafter also referred to as the waves 42, are generated by the ultrasound generator 40, and are generally directed to ^¬ wards the surface 9 through the opening 13 of the suction cup 12. In the embodiment of FIG 11 of the device 1, the waves 42 (not shown in FIG 11) are directed towards the surface 9 through wall of the suction cup 12. The generation of the ultrasound waves 42 from the ultrasound generator 40 requires electrical power which can be provided to the ultrasound gen- erator 40 by connecting the ultrasound generator 40, i.e. the device 1 to an external power source, for example an electri ^¬ cal socket. Alternatively, the housing 10 may include therein a battery to power the ultrasound generator 40. As shown in FIG 5, the surface 9 with the contaminants 99 is subjected to the waves 9 for a predetermined or user- selectable period of time, for example between 1 and 10 minutes . FIG 6 depicts an effect of the waves 42. The ultrasound waves 42 facilitate the dissolution of the contaminants 99 from the surface 9 and into the solvent 5 collected in the volume 7. A rate of dissolving of the contaminants 99 from the surface 9 and into the solvent 5 depends on the frequency of the waves 42 and the time for which the solvent 5 collected within the volume 7 is subjected to the ultrasound waves 42. Further ^¬ more, a level of dissolving, i.e. to what degree or what fraction the contaminants 99 are dislodged from the surface 9 and dissolved into the solvent 5 also depends on the frequen ^¬ cy of the waves 42 and the time for which the solvent 5 is subjected to the waves 42. The waves 42 function as a physi ^¬ cal agitator and preferably generate within the solvent 5 cavitation bubbles that facilitate the dislodging or removal of the contaminants 99 from the surface 9 and subsequent dis ^¬ solution of the contaminants 99 into the solvent 5 standing in the volume 7.

FIG 7 schematically depicts a step 150 and a subsequent step 160 of the method 100 of FIG 8. In the step 150, the solvent 7, after the step 140, is provided to the sensor arrangement 50. The sensor arrangement 50 of the device 1 is configured to detect an electrical property of the solvent 5, for exam ^¬ ple to detect a conductivity or resistivity of the solvent 5 with the contaminants 99 dissolved therein. In the step 160, from the electrical property so detected, an amount of the contaminants 99 present on the surface 9 is determined. Meas ^¬ ure or value of the electrical property of the solvent 5 is indicative of an amount, i.e. a concentration, of contami ^¬ nants 99 present in the solvent 5 that was transferred to the sensor arrangement 50. This amount or concentration of the contaminants 99 present in the solvent 5 is indicative of an amount or a concentration of the contaminants 99 present in the surface 9 that was covered under the suction cup 12 and contacted with the solvent 5 collected in the volume 7.

The sensor arrangement 50, for example a conductivity meter, may comprise sensing component 52, for example electrodes 52, to sense an electrical property of characteristic of the sol ^¬ vent and a microcontroller 54, for example a microprocessor, to analyze the sensed electrical property and derive or de ^¬ termine the amount of contaminants 99 present in the solvent 5 which in turn indicates the amount of contaminants 99 that are present on the surface 9 that was tested.

An indication of the amount of the contaminants 99 so deter- mined is then provided by the readout mechanism 60, for exam ^¬ ple a digital display, for the user or an observer such as a test engineer to read. The readout mechanism 60 may be inte ^¬ grated into the housing 10 surface so as to be perceptible by the user or the observer. The method 100 of FIG 8 depicts the step 170 in which a readout of an indication of the amount of the contaminants 99 so determined is provided.

In an embodiment, the surface contamination testing device 1 has a portable form, i.e. the device 1 is capable of being transported or carried or by hand. In another embodiment, the surface contamination testing device 1 has a hand-held form i.e. the device 1 is appropriately sized or is small enough to be used or operated while being held in the hand or hands of the user.

While the present technique has been described in detail with reference to certain embodiments, it should be appreciated that the present technique is not limited to those precise embodiments. Rather, in view of the present disclosure which describes exemplary modes for practicing the invention, many modifications and variations would present themselves, to those skilled in the art without departing from the scope and spirit of this invention. The scope of the invention is, therefore, indicated by the following claims rather than by the foregoing description. All changes, modifications, and variations coming within the meaning and range of equivalency of the claims are to be considered within their scope.