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Title:
TEST KIT FOR DETECTING ACIDS IN REFRIGERANT LUBRICATING OILS AND METHOD OF USE
Document Type and Number:
WIPO Patent Application WO/2012/166760
Kind Code:
A1
Abstract:
A test kit (10, 10', 110, 110', 310) for detecting acids in refrigerant lubricating oils includes a transparent tube (12, 12', 112, 112') which may be flexible and is selectively sealed at both ends (12a, 12b, 112a, 112b) by end caps (18a, 18b, 18a', 18b', 119, 119' 120) and within which are filters or test pieces (13a, 13b, 13a', 13b', 118). A contact nose (13a-1, 118d) is configured to operate a trigger pin (24, 124) of a Schrader valve (22, 122) to introduce a spray of refrigerant and its entrained lubricating oil from a refrigerant equipment loop into the test kit. Refrigerant gas escapes via exit-end (12b, 112b) leaving behind within the test kit a residue of lubricant oil. A liquid pH indicator (16, 16a, 116, 116a, 316a, 316b) is introduced into contact with lubricating oil residue within the tube either by crushing an ampoule (14, 114, 314a, 314b) by compressing the flexible tube (12, 12', 112, 112'), or via a dispenser (26, 126), to form a pool (17) of liquid reactants in which any color change may be observed.

Inventors:
TOURIGNY JAY S (US)
CUNNINGHAM WELLS (US)
Application Number:
PCT/US2012/039931
Publication Date:
December 06, 2012
Filing Date:
May 30, 2012
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
ZYNON TECHNOLOGIES LLC (US)
TOURIGNY JAY S (US)
CUNNINGHAM WELLS (US)
International Classes:
G01N33/28; F25B43/02; G01N31/22
Foreign References:
US6514765B12003-02-04
US5800782A1998-09-01
US5377496A1995-01-03
Other References:
None
Attorney, Agent or Firm:
LIBERT, Victor E. (20 Church St. 22nd Floo, Hartford Connecticut, US)
Download PDF:
Claims:
CLAIMS

What is claimed is:

1 . An apparatus for separating from a pressurized refrigerant gas a lubricating oil entrained in the gas, and then testing the resulting separated lubricating oil for acidity, the apparatus comprising:

a collection vessel having an entry-end opening and an exit-end opening and defining a fluid flow path from the entry-end opening to and through the exit-end opening;

a contact member disposed adjacent to the entry-end opening and configured to operate a valve of a pressurized refrigeration system to dispense such pressurized refrigerant gas and its entrained lubricating oil into the entry-end opening;

a filter interposed in the flow path within the collection member, the filter being permeable to flow of the refrigerant gas and defining at least one test surface visible from exteriorly of the apparatus and on which the lubricating oil collects, the test surface being configured to be contacted by a liquid pH indicator to form a test liquid comprising such lubricating oil and such liquid pH indicator, whereby visual observation of any color change which takes place in the test liquid may be observed.

2. The apparatus of claim 1 wherein at least a portion of the collection vessel is transparent or translucent to permit visual observation of such test liquid.

3. The apparatus of claim 1 or claim 2 further comprising a storage receptacle containing a quantity of a liquid pH indicator, and wherein the collection vessel is configured to enable the storage receptacle to deposit at least some of the liquid pH indicator onto the test surface.

4. The apparatus of claim 3, wherein the storage receptacle comprises at least one frangible ampoule disposed within the collection vessel, and the collection vessel has a collapsible portion within which the ampoule is disposed, whereby the ampoule may be crushed by squeezing the collapsible portion of the collection vessel to dispense the liquid pH indicator onto the test surface.

5. The apparatus of claim 4 wherein the collection vessel has at least two frangible ampoules disposed within the collapsible portion, and each ampoule contains one or more components of the liquid pH indicator.

6. The apparatus of claim 3 comprising a kit wherein the storage receptacle comprises a dispensing container disposed exteriorly of the collection vessel, and the collection vessel has therein a resealable opening through which the liquid pH indicator may be deposited from the dispensing container onto the test surface.

7. The apparatus of claim 1 or claim 2 wherein the entry-end opening and the exit-end opening each have an openable closure member.

8. The apparatus of claim 1 wherein at least a portion of the collection vessel is transparent to render at least the test surface visible from exteriorly of the collection vessel.

9. The apparatus of claim 1 or claim 2 wherein at least one end of the collection vessel is configured to provide a footprint larger than the rest of the apparatus in order to stabilize the apparatus against tipping over.

10. The apparatus of claim 1 or claim 2 wherein the filter comprises an entry filter facing the entry-end opening and an exit filter facing the exit-end opening.

1 1 . The apparatus of claim 10 wherein the exit filter is less permeable to the lubricating oil than is the entry filter.

12. The apparatus of claim 10 wherein the storage receptacle comprises at least one frangible ampoule disposed within the collection vessel between the entry filter and the exit filter, and the collection vessel has a collapsible portion within which the ampoule is disposed, whereby the ampoule may be crushed by squeezing the collapsible portion of the collection vessel to dispense liquid pH indicator onto the test surface.

13. The apparatus of claim 1 or claim 2 wherein the filter comprises an entry filter disposed at the entry-end opening.

14. The apparatus of claim 13 wherein the storage receptacle comprises at least one frangible ampoule disposed within the collection vessel between the entry filter and the exit-end opening, and the collection vessel has a collapsible portion within which the ampoule is disposed, whereby the ampoule may be crushed by squeezing the collapsible portion of the collection vessel to dispense liquid pH indicator onto the test surface.

15. The apparatus of claim 1 wherein the collection vessel comprises a tube, the entry-end opening has a selectively openable entry-end cap associated therewith and the exit-end opening has a selectively openable exit-end cap associated therewith.

16. The apparatus of claim 15 wherein the tube is transparent.

17. The apparatus of claim 15 or claim 16 wherein the tube has a collapsible portion within which a frangible ampoule containing a pH indicator liquid is contained and the collapsible portion may be compressed by a user's fingers to crush the ampoule to release the pH indicator liquid.

18. A method for separating from a pressurized refrigerant gas a lubricating oil entrained in the gas, and testing the separated oil for acidity, the method comprising:

introducing the pressurized refrigerant gas and its entrained lubricating oil ("the pressurized gas-oil fluid") into a collection vessel defining a flow path for the pressurized gas-oil fluid;

passing the pressurized gas-oil fluid through a filter disposed in the flow path within the collection vessel, the filter having a test surface configured to collect thereon at least some of the entrained lubricating oil, and to pass the resulting filtered refrigerant gas through the filter and out of the collection vessel;

contacting a liquid pH indicator with the collected lubricating oil on the test surface to form a test liquid; and

observing any color change taking place in the test liquid.

19. The method of claim 18 further comprising shaking the apparatus to mix the liquid pH indicator with the entrapped lubricating oil.

20. The method of claim 18 or claim 19 further comprising introducing the pressurized gas-oil fluid into the collection vessel via a resealable entry-end opening in the collection vessel and discharging the refrigerant gas from the collection vessel via a resealable exit-end opening, and resealing the openings prior to contacting the liquid pH indicator with the collected lubricating oil.

21 . The method of claim 18 comprising contacting the pH liquid indicator with the collected lubricating oil by crushing at least one frangible ampoule which is located within the collection vessel and which contains the liquid pH indicator.

22. The method of claim 18 comprising contacting the liquid pH indicator with the collected lubricating oil by dispensing the liquid pH indicator onto the lubricating oil from a storage receptacle located exteriorly of the collection vessel.

23. The method of claim 18 wherein the collection vessel has thereon a contact member, and employing the contact member to operate the trigger of a valve of a pressurized refrigerant system to discharge the pressurized gas-oil fluid into the collection vessel.

Description:
TEST KIT FOR DETECTING ACIDS

IN REFRIGERANT LUBRICATING OILS AND METHOD OF USE

BACKGROUND OF THE INVENTION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001 ] This application claims the benefit of priority of provisional patent application Serial No. 61/492,1 18, filed on June 1 , 201 1 , entitled "Test Kit For Detecting Acids in Refrigerant Lubricating Oils and Method of Use", and provisional patent application Serial No. 61/510,532, filed on July 22, 201 1 , entitled "Extended Surface Test Kit For Detecting Acids in Refrigerant Lubricating Oils and Method of Use".

Field of the Invention

[0002] The present invention concerns devices for testing the acidity of lubricating oils dispersed in the refrigerant of refrigeration systems such as air conditioners, ice-making equipment, refrigerators and the like, and methods of use of the devices.

Related Art

[0003] Refrigerant systems utilize lubricating oil which is mixed with the refrigerant and thereby undergoes the same cyclic compression and expansion as the refrigerant. Generally, four different types or classes of lubricants are used in refrigerant systems. One class is mineral oil, another class is ester oil (which is based on the chemistry of polyol esters and is below referred to simply as "polyol ester oil"), the third class is polyalkaline glycol (PAG) oils and the fourth class is an alkylbenzene oil of the type commonly known as Zerol. The mineral oil is used for chlorofluorohydrocarbon ("CFC") refrigerants such as those sold under the trademark FREON, and hydrochlorofluorocarbon ("HCFC") refrigerants such as those designated R22. New refrigerants which are replacing CFCs and HCFCs are not soluble in mineral oil, so mineral oil is effectively being phased out along with the CFCs and HCFCs. Under the repeated compression and expansion cycles moisture or other impurities present in the system tend to chemically react with the lubricating oil to produce acidic reaction products. Even a very small amount of acid in the refrigerant system wreaks havoc on the refrigeration equipment, most notably the system's compressor. Checking the system for acid is a routine maintenance procedure in a large commercial air conditioning or refrigeration system because, if detected early enough, acidic components can be economically removed from the system before the compressor or other parts of the system are irreparably damaged. [0004] Litmus paper is sometimes used to test the lubricant oil in large systems for acidity, but is not sensitive enough to provide a timely indication of low levels of acidic components present in the oil. By the time the litmus paper turns pinkish to indicate the presence of acid, the acid content is already high enough that the refrigerant system equipment has likely sustained significant damage.

[0005] Other acid test kits are known but these are generally complicated and, like the litmus paper test, require an oil sample size usually measured in multiple milliliters ("ml"), for example, 10 to 30 ml. Withdrawing that amount of lubricating oil for testing is feasible in large commercial refrigeration and air conditioning systems but is not feasible or even possible for smaller systems, such as small to medium size air conditioning units, window or other small capacity air conditioners, household refrigerators, household and automotive air conditioning systems and the like.

[0006] The terms "lubricant" and "lubricating oil" and their plural forms are used interchangeably below. As used herein and in the claims, reference in the singular or plural to "refrigerant gas" or "refrigerant system" or "refrigerant", unless otherwise specified, means broadly any gas or system or the like used for refrigeration, air conditioning, ice-making, or any other cooling operations wherein a gas is alternately compressed and expanded.

SUMMARY OF THE INVENTION

[0007] In accordance with the present invention, there is provided a highly sensitive test apparatus and method for detecting even very low levels of acidity in lubricants of refrigerant systems, and which requires only a very small size lubricant sample. The apparatus and procedure of the present invention may be used on small refrigerant systems where withdrawing from the system of a significant size oil sample is not feasible or even possible, but the present invention is not limited to such small systems and may be employed in any size system.

[0008] Generally, the apparatus aspect of the present invention provides a highly sensitive test for the presence of acid using a very small size lubricant test sample, for example, about 0.5 ml of lubricant. This size lubricant sample requires withdrawing only a small size lubricant/refrigerant sample from the refrigerant system. That small a sample size is readily obtainable by utilizing the apparatus of the present invention to depress the trigger pin or button of a conventional Schrader valve. Every refrigerant system, small and large, contains a Schrader valve which functions in a manner similar to the valve on an automobile tire. That is, depressing the pin or button in the valve permits flow through the valve in either direction, depending on the respective pressures on either side of the valve. [0009] Specifically, in accordance with the present application there is provided an apparatus for separating from a pressurized refrigerant gas a lubricating oil entrained in the gas, and then testing the resulting separated lubricating oil for acidity. The apparatus may comprise the following components. A collection vessel, which optionally may be in the form of a tube, has an entry-end opening and an exit-end opening and defines a fluid flow path from the entry-end opening to and through the exit-end opening. A contact member is disposed adjacent to the entry-end opening and is configured to operate a valve of a pressurized refrigeration system to dispense such pressurized refrigerant gas and its entrained lubricating oil into the entry-end opening. A filter is interposed in the flow path within the collection member, the filter being permeable to flow of the refrigerant gas and defining at least one test surface visible from exteriorly of the apparatus and on which the lubricating oil collects. The test surface is configured to be contacted by a liquid pH indicator to form a test liquid comprising such lubricating oil and such liquid pH indicator, whereby visual observation of any color change which takes place in the test liquid may be observed.

[0010] Other apparatus aspects of the present invention provide one or more of the following features, alone or in any suitable combination. At least a portion of the collection vessel is transparent or translucent to permit visual observation of such test liquid; the apparatus may further comprise a storage receptacle containing a quantity of liquid pH indicator, and the collection vessel is configured to enable the storage receptacle to deposit at least some of the liquid pH indicator onto the test surface; the storage receptacle may comprise at least one frangible ampoule disposed within the collection vessel, which has a collapsible portion within which the ampoule is disposed, whereby the ampoule may be crushed by squeezing the collapsible portion of the collection vessel to dispense the liquid pH indicator onto the test surface; the collection vessel may have at least two frangible ampoules disposed within the collapsible portion, with each ampoule containing one or more components of the liquid pH indicator; the apparatus may comprise a kit wherein the storage receptacle comprises a dispensing container disposed exteriorly of the collection vessel, and the collection vessel has therein a resealable opening through which the liquid pH indicator may be deposited from the dispensing container onto the test surface; the entry-end opening and the exit-end opening may each have an openable closure member; and at least one end of the collection vessel is configured to provide a footprint larger than the rest of the apparatus to stabilize the apparatus against tipping over.

[001 1 ] Generally, the method aspect of the present invention provides for impregnating a porous and permeable test piece with a small sample of the lubricating oil to be tested, preferably by utilizing the contact member of the apparatus to operate a valve to dispense pressurized refrigerant gas into the test apparatus. Specifically, a method aspect of the pre- sent invention provides a method for separating from a pressurized refrigerant gas a lubricating oil entrained in the gas, and testing the separated oil for acidity. The method comprises the following steps: (a) introducing the pressurized refrigerant gas and its entrained lubricating oil ("the pressurized gas-oil fluid") into a collection vessel defining a flow path for the pressurized gas-oil fluid; (b) passing the pressurized gas-oil fluid through a filter disposed in the flow path within the collection vessel, the filter having a test surface configured to collect thereon at least some of the entrained lubricating oil, and to pass the resulting filtered refrigerant gas through the filter and out of the collection vessel; (c) contacting a liquid pH indicator with the collected lubricating oil on the test surface to form a test liquid; and (d) observing any color change taking place in the test liquid.

[0012] The method of the present invention may include one or more additional method steps as follows, alone or in any suitable combination: shaking the apparatus to mix the liquid pH indicator with the entrapped lubricating oil; introducing the pressurized gas-oil fluid into the collection vessel via a resealable entry-end opening in the collection vessel and discharging the refrigerant gas from the collection vessel via a resealable exit-end opening, and resealing the openings prior to contacting the liquid pH indicator with the collected lubricating oil; contacting the pH liquid indicator with the collected lubricating oil by crushing at least one frangible ampoule located within the collection vessel, the ampoule containing the liquid pH indicator; contacting the liquid pH indicator with the collected lubricating oil by dispensing the liquid pH indicator onto the lubricating oil from a storage receptacle located exteriorly of the collection vessel; and the collection vessel has thereon a contact member, and employing the contact member to operate the trigger of a valve of a pressurized refrigerant system to discharge the pressurized gas-oil fluid into the collection vessel.

[0013] Other aspects of the present invention will be apparent from the following description and the appended drawings.

[0014] As used herein, a "flexible" collection vessel, e.g., a tube, means a collection vessel which can be compressed sufficiently to crush an appropriately sized frangible ampoule within the collection vessel, without breaking the collection vessel in order to protect the interior of the collection vessel from the ambient environment and maintain the collection vessel liquid-tight. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is an exploded elevation view of a test kit in accordance with one embodiment of the present invention comprising a tube which is selectively sealable at both ends thereof;

[0016] Figure 1 A is a cross-sectional elevation view, enlarged relative to Figure 1 , of the portion of Figure 1 enclosed by circle A;

[0017] Figure 1 B is a plan view, enlarged relative to Figure 1 , of the exit filter component of the test kit of Figure 1 ;

[0018] Figure 1 C is a plan view, enlarged relative to Figure 1 , of the entry filter component of the test kit of Figure 1 , showing the side of the filter which faces outwardly of the tube;

[0019] Figure 1 D is an elevation view, enlarged relative to Figure 1 , of the entry filter component of the test kit of Figure 1 ;

[0020] Figure 2 is an assembled elevation view of the test kit of Figure 1 ;

[0021 ] Figure 3 is a partial elevation view, enlarged relative to Figures 1 and 2, and partly in cross section, showing the entry filter component of the test kit of Figure 1 about to engage the trigger pin of a conventional Schrader valve; and

[0022] Figure 4 is an elevation view of a test kit in accordance with a second embodiment of the present invention, showing the test kit in use;

[0023] Figure 5 is an exploded elevation view of a test kit in accordance with a third embodiment of the present invention;

[0024] Figure 5A is an elevation view, enlarged relative to Figure 5, of a component of the test kit of Figure 5;

[0025] Figure 6 is an assembled elevation view of the test kit of Figure 5;

[0026] Figure 7 is a partial elevation view, enlarged relative to Figures 5 and 6, showing the test piece of the kit of Figure 5 about to engage the trigger pin of a conventional Schrader valve;

[0027] Figure 8 is an elevation view with portions broken away of a fourth embodiment of the present invention comprising a test piece usable in the test kit;

[0028] Figure 9 is an elevation view of a test kit in accordance with a fifth embodiment of the present invention, showing the kit in use; and

[0029] Figure 10 is an elevation view of a test kit in accordance with a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

AND SPECIFIC EMBODIMENTS THEREOF

[0030] Figures 1 -3 illustrate a first embodiment of the invention wherein the apparatus comprises a test kit and the collection vessel comprises a flexible, transparent tube 12 which is closed at both its opposite ends by openable seals, e.g., end caps. That is, each end of the tube 12 may be sealed by caps or the like which are each moveable between a closed position in which the tube 12 is sealed and an open position which opens the respective ends of the tube. A porous, i.e., permeable, and non-absorbent, filter is disposed adjacent each end of the tube 12. Figures 1 and 2 show, respectively, exploded and assembled views of an apparatus, i.e., a test kit 10 in accordance with one embodiment of the present invention. The test kit 10 comprises a flexible transparent tube 12 having an entry-end 12a and an exit-end 12b. A frangible ampoule 14 has sealed within it a liquid pH indicator 16, for example, one comprising a pH indicator such as phenolphthalein and a liquid solvent/carrier liquid such as toluene, isopropyl alcohol, methanol, ethyl alcohol or blends of two or more thereof. This mixture is adjusted by the addition of base or acid to a pH above the titration point of the indicator creating, in the case of phenolphthalein, its purple color phase. The adjustment should be such that contact with another liquid phase of a selected minimum acid number will effectuate a discernible color change in the particular pH indicator used. Different acid numbers are selected for different classes of lubricant oils, as described below, because some classes of lubricant oils can safely (for the refrigerant equipment) carry a higher acidic content than can others. As best seen in Figure 2, ampoule 14 is dimensioned and configured to be received within flexible transparent tube 12 between an entry filter 13a and an exit filter 13b. Frangible ampoule 14 may be made of a suitable glass or any other suitable frangible material such as an acid-free synthetic polymeric material.

[0031 ] Filters 13a and 13b are best seen in Figure 1 B (filter 13b) and Figures 1 C and 1 D (filter 13a). The filter at or adjacent to the bottom of the tube, i.e., the entry filter 13a, may be constructed to be more permeable to the lubricating oil than is the filter located at or adjacent the top of the tube, i.e., the exit filter 13b. This will facilitate slowing the velocity of the discharging gas to enhance the retaining of the lubricating oil within the tube 12 while still permitting escape of the refrigerant gas.

[0032] The collection vessel, provided in this embodiment by the transparent tube 12, has a fixture on the entry-end thereof that is used to depress the pin or button trigger of a Schrader valve in a refrigerant system. Alternatively, the entry-end of the tube or the test piece itself may be configured to provide a contact member to be used for the purpose. Pressing the pin or button ("the trigger") of the Schrader valve directs a controlled spray of refrigerant and its entrained lubricating oil onto the porous and highly oil-permeable test piece. The test piece is sufficiently porous and provides sufficient permeability to both the refrigerant gas and its entrained lubricant oil, by capillary action or otherwise for the oil, that the refrigerant gas, or at least a significant portion of it, escapes from the test piece, and the lubricating oil is left behind in the test piece. The permeability of the test piece is great enough so that the lubricating oil is dispersed substantially throughout the test piece, to and including the surface thereof which is exposed to the liquid pH indicator. In the embodiment of Figures 1 and 2, filter 13b is disc-shaped (Figures 1 A and 1 B) and filter 13a (Figure 1 D) is disc-shaped but carries thereon a contact member which in this embodiment is provided by a longitudinally-protruding contact nose 13a-1 which terminates in a recessed contact surface 13a-2. Filters 13a and 13b are mounted in a fixed position within flexible, transparent tube 12 in any suitable way. Figure 1 A illustrates one way of mounting both filters 13a and 13b, by illustrating exit filter 13b mounted by an interference fit within tube 12. The use of filters 13a, 13b of a diameter which provides a slight interference fit with the interior wall 12c of tube 12 facilitates ease of construction. Alternatively, grooves lying in a plane which is perpendicular to the longitudinal axis of tube 12 may be used to snap-fit the filters 13a, 13b into such grooves.

[0033] Obviously, any other suitable schemes for mounting the filters 13a and 13b within tube 12 may be used. For example, filters 13a and 13b may be connected by one or more longitudinally extending (relative to tube 12) ribs or supports (not shown) to form a unitary assembly (not shown) of the filters 13a, 13b. The ribs or supports may extend beyond one or both of entry filters 13a, 13b to a shoulder or other support (not shown) formed at or adjacent one or both of entry-end 12a and exit-end 12b of tube 12. During manufacture or assembly, such unitary assembly of filters 13a and 13b may be inserted into tube 12 from either entry-end 12a or exit-end 12b until the ribs or supports contact a shoulder or other support (not shown) on tube 12. Alternatively, the ribs or supports of such unitary filter assembly could flare outwardly along one or more segments of their length, to a distance greater than the inside diameter of the tube 12 into which they are to be inserted. The outwardly-flared segments could be between the filters 13a, 13b and/or extend beyond one of both of filters 13a and 13b. The ribs or supports would in such case be flexible and resilient enough to be compressed by the interior wall 12c of the tube 12 when inserted into the tube, thereby holding the filler assembly in position within the tube 12. This would permit the use of tubes with smooth interiors, thereby reducing manufacturing and assembly costs.

[0034] One or more of the filters may provide a "test piece" which provides a surface to facilitate observing the color change. The filters may be made of any suitable material which is non-absorbent, has a porosity which will trap the lubricating oil while allowing the refrigerant gas to flow through, and which will readily shed the oil when washed with the liq- uid pH indicator. For example, the filters may be made of chemically resistant sintered polymer particles or bonded polymer fiber or similar permeable and porous materials made from non-staining and chemically resistant metal such as 300 series stainless steel or combinations of two or more thereof. The filters preferably should have a minimum void volume of 40% to 90%. The filters will be sufficiently porous to allow for rapid outgassing of the refrigerant while simultaneously trapping refrigerant lubricating oil within the filter's pore structure and within the tube. One or both of the test piece, the interior wall of the tube and the exterior surface of the ampoule, or at least the portions thereof on which lubricant oil is deposited for reaction with the liquid pH indicator, may be treated with surface enhancements such as surfactants or other materials that serve to enhance one or more of adherence by the oil, test sensitivity and test accuracy.

[0035] The porous test piece is preferably a colorfast white in color. A uniform white surface provides the ideal test surface for visual confirmation of the color change reaction or lack thereof, indicating whether detectable amounts of acidic compounds are present in the lubricant. The uniform white color also provides the ideal surface to detect discoloration of the refrigerant oil, which is normally clear. Discoloration of the oil is indicative of deterioration of the oil through oxidation, which can also indicate the presence of acid or other impurities in the refrigerant.

[0036] The ampoule in which the liquid pH indicator is contained, or at least the ampoule interior which contacts the liquid pH indicator, is made of a material which is impermeable, pH neutral, and non-reactive, such as, for example, USP (United States Pharmacopeia) Type I glass, a borosilicate glass composed principally of silicon dioxide and boric oxide, with low levels of non-network forming oxides. It is a chemically resistant glass exhibiting low leachability and a low thermal coefficient of expansion and provides enhanced pH stability. Regardless of the material of construction of the ampoule, the interior of the ampoule may be filled with an inert gas such as nitrogen in the course of filling the ampoule with the liquid pH indicator in order to displace air and prevent its entrapment in the sealed ampoule. This will provide an environment within the filled and hermetically sealed ampoule to provide for a maximum shelf life of the liquid pH indicator. For example, the presence of carbon dioxide within the ampoule can cause the liquid pH indicator to lose sensitivity over time and compromise its ability to react properly when exposed to acid, which can cause false negative results.

[0037] The ampoule containing the liquid pH indicator is held captive inside the flexible transparent tube and on or near the test piece filter or filters. A removable cap or other removable seal serves to close both the entry- and exit-ends, i.e., the top and the bottom, of the flexible transparent tube 12. The removable end caps 18a, 18b serve to protect the inte- rior of the transparent tube from contamination prior to use and to close the tube to permit shaking the tube to mix the liquid pH indicator and the lubricating oil residue within the tube.

[0038] The slightly alkaline liquid pH indicator may be comprised of phenolphthalein in a carrier-solvent such as toluene and isopropyl alcohol ("TIA"). The carrier-solvent component of the liquid pH indicator serves to dissolve the oil residue it contacts and strip out of the oil any acid present in it to thereby facilitate reaction of any such acid with the phenolphthalein. While other carrier-solvents and pH indicators may be used, the combination of phenolphthalein and TIA may be formulated to give the darkest purple hue so far attainable. The liquid pH indicator is carefully balanced to be barely alkaline so that a very small amount of acid will trigger a color change in which the liquid pH indicator or a part thereof will turn, in the case of a phenolphthalein-TIA test liquid, from a dark purple to a lighter shade or rose color, or even to a clear or clear yellow liquid, in the presence of even small amounts of acid.

[0039] The procedure or method for testing acidity of the oil comprises impregnating a porous and permeable test piece with the lubricant oil to be tested. For example, this aspect of the present invention may comprise collecting within a transparent or translucent member of the test kit a small sample of the lubricant oil to be tested. Such impregnation or collecting may be carried out, for example, by utilizing the test kit to operate the trigger pin of a refrigerant system's Schrader valve so that refrigerant gas, including the lubricant oil entrained in it, is expelled via the Schrader valve from the refrigerant system into the test kit. The refrigerant gas may be vented from the test kit through one or more porous, non- absorbent filters, sometimes herein referred to as "test pieces", leaving behind on the test piece or pieces a residue of the lubricant oil within a preferably transparent or translucent portion of the test kit. In one embodiment the expelled refrigerant gas and the lubricating oil entrained in the gas impregnates a test piece and the lubricant oil permeates to a top or test surface of the test piece. In any case, when the test piece is sufficiently wetted by the lubricating oil, the tube is withdrawn from the refrigerant system valve, for example, a Schrader valve, and both the entry-and exit-ends of the tube are sealed with the caps or other sealing members. The liquid pH indicator is then contacted with the lubricating oil residue and the operator observes the color change, if any, which occurs. The method preferably includes utilizing a test kit in which the top or test surface of the test piece, and/or some other surface on which the lubricant oil gathers, is disposed within the transparent or translucent portion of the test kit. The transparent or translucent portion may comprise a transparent tube or container into which the oil residue is deposited, and into which a liquid pH indicator is placed into contact with the oil residue to form a pool of liquid reactants. The transparency of the tube facilitates observing any color change which takes place in the pool of liquid. [0040] The liquid pH indicator may be placed into contact with the lubricant oil residue either by dispensing the liquid pH indicator from an external dispenser into the tube which can be opened for that purpose, or by utilizing a tube, e.g., a closed tube, which is flexible as well as transparent (or translucent) and crushing a frangible ampoule contained within the tube. The frangible ampoule contains the liquid pH indicator which, upon the ampoule being crushed, contacts the lubricant oil residue to form the liquid pool.

[0041 ] The sealed tube is then shaken for a time in order to thoroughly mix the collected lubricating oil with the liquid pH indicator and to allow any color change reaction to develop. It may not be necessary for the shaking to continue for the entire time allotted to observe whether or not a color change reaction takes place. If the entire quantity of liquid pH indicator retains its original color, the refrigerant does not contain a detectable acid level. If the liquid pH indicator undergoes a color change or a change in color intensity, either of which may appear throughout the entire quantity of liquid pH indicator, or in streaks or other localized portions of the liquid pH indicator captured on the filter, i.e., test piece, or elsewhere within the tube, that means detectable levels of acid are present in the lubricating oil. This indicates to the operator that it is time to service the system to remove the acidic content by either treating or replacing the lubricant oil. This liquid pH indicator works by detecting the presence of acid in any of the above-mentioned three standard refrigerant lubricants, but its functionality is not limited to the specific oils mentioned above. In contrast, many prior art test systems are specific to only one type of lubricant oil.

[0042] In use, the interior of the tube 12 is exposed by removing the removable end caps 18a, 18b from each end of the transparent tube. The tube may have a contact member such as contact nose 13a-1 (Figure 1 D) on the bottom thereof that is used to depress the trigger pin or button of the Schrader valve (item 22 in Figure 3, described below) in the refrigerant system. Alternatively, the bottom of the tube itself may be configured to be used for the purpose, or the filter located at or adjacent the bottom of the tube may be configured to be used for the purpose. As used herein, the "bottom" or "entry-end" of the tube means the end of the tube which is positioned on the Schrader valve and through which the refrigerant gas and its entrained lubricating oil enters the tube. Pressing the pin or button ("the trigger") of the Schrader valve with the test kit with both end caps removed from the tube directs a controlled spray of refrigerant and its entrained lubricating oil into the interior of the tube. The refrigerant gas passes through the entry (bottom) end filter, around the ampoule and out through the exit (top) end filter, thence out the top or "exit-end" of the tube. Most or at least much of the lubricating oil is left behind within the tube, coating the interior wall of the tube and the outside surface of the ampoule. The filters are sufficiently porous and provide sufficient permeability to both the refrigerant gas and its entrained lubricant oil that the refrigerant gas, or at least a significant portion of it, escapes from the test kit tube, and much of the lubricating oil is left behind within the tube.

[0043] The outside diameter D-a of ampoule 14 (Figure 1 ) is less than the inside diameter D-t of tube 12 (Figures 1 and 1 A) to permit refrigerant to flow around ampoule 14 and exit tube 12 via exit-end 12b thereof. Exit-end cap 18b selectively, i.e., removably, closes exit-end 12b of tube 12 and entry-end cap 18a selectively closes entry-end 12a of tube 12. Figure 1 shows end caps 18a and 18b in the open position and Figure 2 shows them in the closed position. End caps 18a and 18b are illustrated as connected to tube 12 by respective integrally molded hinges 20a, 20b. Obviously, however, the end caps could be connected to tube 12 by lanyards or, less preferably, end caps 18a and 18b could be loose, i.e., not connected to tube 12. As described, the end caps at the entry-end or the exit-end of the tube may be configured with a wide pedestal-type footprint to allow the kit to be positioned in an upright vertical position after the ampoule has been broken, allowing the combined fluids to concentrate in one end of the tube for ease of viewing. The end caps may be configured to snap onto the respective ends of the tube to form a liquid-tight seal. If loose, the end caps and the tube ends could be configured to have an interference friction-fit or screw threads so that the end caps can be force-fit or screwed onto the tube ends to form the liquid-tight seals.

[0044] Flexible transparent tube 12 is flexible enough so that application of pressure of an operator's thumb and forefinger as indicated by the unnumbered arrows in Figure 2, will collapse tube 12 sufficiently to enable the operator to crush ampoule 14, as described below.

[0045] In order to ensure during transit and storage a tight environmental seal between the end caps 18a and 18b and the corresponding ends of flexible transparent tube 12, a suitable removable seal such as a removable tape seal (not shown) or a removable shrink wrap seal (not shown) may be used to close the joints between the end caps 18a, 18b and the exterior of the respective ends of flexible transparent tube 12.

[0046] In use, any seal or shrink wrap joining end caps 18a and 18b to the ends of flexible transparent tube 12 is removed and both end caps 18a and 18b are opened as shown in Figure 1 . The exterior end of a conventional Schrader valve 22 suitably mounted to the refrigerant loop of a refrigerant system (not shown) is shown in Figure 3. The upper, exteriorly threaded portion 22a of Schrader valve 22 is shown in cross section in order to reveal trigger pin 24 of Schrader valve 22. Figure 3 shows that the recessed contact surface 13a-2 of contact nose 13a-1 of entry filter 13a has not yet contacted trigger pin 24. However, with the operator advancing flexible transparent tube 12 downwardly in the direction shown by the arrow P in Figure 3, contact surface 13a-2 seats on the dome-shaped top (un- numbered) of trigger pin 24 and depresses trigger pin 24 to release the pressurized refrigerant from the pressure vessel or line on which Schrader valve 22 is mounted. When depressed, trigger pin 24 will release the pressurized contents from the refrigerant loop (not shown) on which the Schrader valve is mounted. This will release pressurized refrigerant and entrained lubricating oil to flow in the direction of the unlabeled arrows in Figure 3 so that the released refrigerant penetrates the porous entry filter 13a, flows into tube 12, around ampoule 14, and then through exit filter 13b and out of tube 12 via exit-end 12b. Much if not substantially all the refrigerant gas will escape from tube 12 via this route and leave behind the lubricating oil, or at least a substantial portion of it, coating at least portions of the interior wall 12c of tube 12 and the exterior surface 14a (Figures 1 and 2) of ampoule 14. The operator then removes flexible transparent tube 12 from the Schrader valve 22 to disengage entry filter 13a from Schrader valve trigger pin 24, thereby permitting trigger pin 24 to return to its normal, valve-closed position.

[0047] Variations may be made to entry filter 13a which, for example, may be hardened or reinforced in any suitable way so it has sufficient mechanical strength to operate the Schrader valve trigger pin 24. Entry filter 13a may be made in whole or in part of an engineered plastic or of metal for enhanced strength.

[0048] At this point, the operator seals tube ends 12a and 12b by closing, respectively, end caps 18a and 18b to seal the lubricating oil residue and ampoule 14 within tube 12. The operator then squeezes transparent flexible tube 12 between thumb and forefinger as indicated by the unlabeled arrows in Figure 2, in order to crush frangible ampoule 14 and release liquid pH indicator 16 to contact the lubricating oil residue to form a pool of liquid re- actants adjacent entry-end 12a and closed entry-end cap 18a of tube 12. (The pool of liquid reactants is not shown in Figure 1 but is shown at 17 in Figure 4.) Alternatively, the combined oil and indicator solution may be captured in the porous filter media 13a to enhance the visibility of a potential color change. If, after shaking tube 12 vigorously and allowing time for any color-change reaction to take place, the liquid pH indicator 16, or a portion thereof, undergoes a color change, it means that a detectable amount of acidic components is present and appropriate maintenance action should be taken. If there is no color change in the liquid pH indicator or in a portion thereof, it means that there is not a detectable (by the liquid pH indicator) amount of acidic component in the lubricating oil and the refrigerant equipment may continue to safely operate until it is time for the next test.

[0049] The size of a "standard" test kit 10 may be selected so that even a small sample, for example, 0.5 ml of lubricant oil residue, will be trapped within tube 12. As illustrated in Figure 1 , such a "standard" size of test kit 10 would have a length, dimension L in Figure 1 , of about 2 to about 3.5 inches (about 5.1 to about 8.9 cm), an inside diameter D-t (Figures 1 and 1 A) of flexible transparent tube 12 of about 1/4 to about 1/2 inch (about 0.64 to about 1 .27 cm), and ampoule 14 would have an outside diameter D-a (Figure 1 ) less than that of D-t by an amount sufficient to allow the refrigerant gas to pass around ampoule 14 to and through exit filter 13b. Ampoule 14 would also be sized to be able to hold from about 0.5 to about 6.0 ml of liquid pH indicator. Obviously, test kit 10 may be made of any suitable size as needed for a particular purpose. The "standard" dimensions given above enable the recessed contact surface 13a-2 of entry filter 13a to fit into a Schrader valve of the size typically used on small refrigerant units, as illustrated in Figure 3.

[0050] Figure 4 illustrates another embodiment of the present invention in which the test kit differs from the first embodiment essentially only in that the ampoule containing the liquid pH indicator is omitted and instead, after passing the refrigerant gas through the tube with both end caps in the open position, the exit-end cap is left open and the entry-end cap is closed. This enables dispensing a premeasured dose of liquid pH indicator from a suitable dispenser into the transparent tube. The exit-end cap is then closed and the tube is shaken to mix the liquid pH indicator with the trapped lubricating oil to provide a pool 17 of liquid reactants. In this second embodiment, the transparent tube 12' need not be flexible as there is no ampoule to be crushed within the tube. Therefore, tube 12' may be made of a suitable glass or rigid, non-flexible plastic material. Figure 4 shows a second embodiment of the test kit of the invention in use. The components of Figure 4 which have the same or similar structure and function as the components of the test kit illustrated in Figures 1 and 2 are identically numbered to the corresponding components in Figures 1 and 2 except for the addition of a prime indicator and are described only with respect to differences from the embodiment of Figures 1 and 2. Figure 4 shows the test kit 10' in use after the entry filter (test piece) 13a and the interior wall 12c' of tube 12', or at least portions thereof, have been coated with lubricating oil residue in the same manner as described above for the test kit of Figures 1 and 2. As illustrated, exit-end cap 18b' has been moved to its open position shown in Figure 4 in solid line, from its closed position shown in Figure 4 in dash lines. A dispenser 26 is shown as depositing drop-wise one or more drops 16a of a liquid pH indicator into tube 12' to contact lubricant oil residue therein and form a pool 17 of liquid reactants above entry- end cap 18a'. The tube of any embodiment of the invention is made translucent or, preferably, transparent at least in the area in which the pool 17 of liquid reactants gathers. Dispenser 26 may be the type of dispenser which provides accurately reproducible drop sizes, or contain a premeasured volume of fluid that is fully discharged in order to assist the operator in dispensing an appropriate amount of liquid pH indicator. As with the liquid pH indicator dispersed by crushing the ampoule 14 of the Figure 2 embodiment, sufficient liquid pH indicator is to be dispensed in order to provide a discernible color change if the acid number of the tested lubricant oil is high enough, but not so much of the liquid pH indicator is used so as to "drown" the lubricant oil and thereby make any color change difficult or even impossible to read.

[0051 ] Figures 5-7 illustrate a third embodiment of the invention comprising a test kit comprising a flexible transparent tube, at the entry-end (bottom) of which is a porous test piece. Above the test piece and contained within the flexible tube is a frangible ampoule which may be made of glass or any other suitable frangible material such as a synthetic polymeric material. The ampoule contains a liquid pH indicator, for example, one comprising a pH indicator such as phenolphthalein and a liquid solvent/carrier liquid such as toluene, iso- propyl alcohol, methanol, ethyl alcohol or blends of two or more thereof. This mixture is adjusted by the addition of base or acid to a pH above the titration point of the indicator, in the case of phenolphthalein creating the purple or blue color phase of phenolphthalein. The adjustment should be such that contact with another liquid phase of a selected minimum acid number will effectuate a discernible color change in the particular pH indicator used. Different acid numbers are selected for different classes of lubricant oils, as described below, because some classes of lubricant oils can safely (for the refrigerant equipment) carry a higher acidic content than can others. The ampoule containing the liquid pH indicator is held captive inside the flexible transparent tube between the closed exit-end of the tube and a test piece which is located at the opposite and open entry-end of the tube. The test piece is enclosed within a removable cap or other removable seal, which also serves to enclose the entry-end of the flexible transparent tube. The removable cap serves to protect the test piece and the interior of the transparent tube from contamination prior to use.

[0052] Figures 5 and 6 show, respectively, exploded and assembled views of a test kit 1 10 in accordance with another embodiment of the present invention. The test kit 1 10 comprises a flexible transparent tube 1 12 having an open, entry-end 1 12a and an exit-end 1 12b (best seen in Figure 5) which may be selectively opened and closed by exit-end cap 1 19. A frangible ampoule 1 14 has sealed within it a liquid pH indicator 1 16. As best seen in Figure 6, ampoule 1 14 is dimensioned and configured to be received within flexible transparent tube 1 12. Closed, bottom end 120b fits over a lower portion of tube 1 12 and encloses open entry-end 1 12a thereof. As best seen in Figure 5A, a test piece 1 18 is of generally cylindrical configuration and has a top section 1 18a which terminates in a top surface 1 18f, and a middle section 1 18b. Top section 1 18a and middle section 1 18b are each circular in cross section and middle section 1 18b is of larger diameter than top section 1 18a to define between the sections a circumferential shoulder 1 18c. A nose 1 18d has a generally truncated conical shape and extends from the end of middle section 1 18b which is opposite to top section 1 18a. Nose 1 18d terminates in a recessed contact surface 1 18e. [0053] As shown in Figures 5A and 7, top section 1 18a of test piece 1 18 snugly fits within the entry-end 1 12a of flexible transparent tube 1 12 with the entry-end 1 12a of tube 1 12 seated on circumferential shoulder 1 18c. Flexible transparent tube 1 12 is flexible enough so that application of pressure of an operator's thumb and forefinger as indicated by the unnumbered arrows in Figure 6, will collapse tube 1 12 sufficiently to enable the operator to crush ampoule 1 14.

[0054] In order to ensure a tight environmental seal between closure cap 120 and flexible transparent tube 1 12, a suitable removable seal such as a removable tape seal (not shown) or a removable shrink wrap seal (not shown) may be used to close the joint between top end 120a of closure cap 120 and the exterior of flexible transparent tube 1 12. Alternatively, an interior thread (not shown) may be formed on closure cap 120 adjacent top end 120a thereof and a matching exterior thread (not shown) may be formed on the exterior of flexible transparent tube 1 12 along a section thereof extending from entry-end 1 12a towards exit-end 1 12b whereby closure cap 120 may, in a screw-thread embodiment, be screwed onto and unscrewed from flexible transparent tube 1 12.

[0055] In use, any seal or shrink wrap joining closure cap 120 to flexible transparent tube 1 12 is removed or closure cap 120 is unscrewed from tube 1 12, to remove closure cap 120 from flexible transparent tube 1 12 and thereby expose test piece 1 18. The exterior end of a conventional Schrader valve 122 suitably mounted to the refrigerant loop of a refrigerant system (not shown) is shown in Figure 7. The upper, exteriorly threaded portion 122a of Schrader valve 122 is shown in cross section in order to reveal trigger pin 124 of Schrader valve 122. Figure 7 shows the recessed contact surface 1 18e (Figure 5A) of test piece 1 18 has not yet contacted trigger pin 124. However, with the operator advancing flexible transparent tube 1 12 downwardly in the direction shown by the arrow P in Figure 7, contact surface 1 18e seats on the dome-shaped top of trigger pin 124 and depresses trigger pin 124 to release the pressurized refrigerant from the pressure vessel on which Schrader valve 122 is mounted. When depressed, trigger pin 124 will release the pressurized contents from the refrigerant loop (not shown) on which the Schrader valve is mounted. In such case, this will release pressurized refrigerant and entrained lubricating oil in the direction of the unlabeled arrows in Figure 7 so that the gas penetrates the porous, high-capillary action test piece 1 18. Much if not substantially all the refrigerant gas will escape from test piece 1 18 and leave behind the lubricating oil to soak the test piece 1 18 through and to the top surface 1 18f, which faces ampoule 1 14. The operator then removes flexible transparent tube 1 12 and test piece 1 18 from Schrader valve 122, thereby permitting trigger pin 124 to return to its normal, valve- closed position. [0056] At this point, the operator squeezes transparent flexible tube 1 12 between thumb and forefinger as indicated by the unlabeled arrows in Figure 6, in order to crush frangible ampoule 1 14 and release liquid pH indicator 1 16 to contact top section 1 18a of test piece 1 18 and penetrate into its interior. If the liquid pH indicator 1 16, or a portion thereof, undergoes a color change, it means that a detectable amount of acidic components is present and appropriate maintenance action should be taken. If there is no color change in the liquid pH indicator or in a portion thereof, it means that there is not a detectable amount of acidic component in the lubricating oil and the refrigerant equipment may continue to safely operate until the next test.

[0057] The size of a "standard" test kit 1 10 may be selected so that the high-capillary action and porosity of test piece 1 18 will cause even a small sample, for example, 0.5 ml of lubricant oil, to permeate the entire test piece 1 18, including the entire volume of top section 1 18a thereof. Such a "standard" size of test kit 1 10 would have its length L of Figure 6 measuring about 2 to about 3 inches (about 5.1 to about 7.6 cm), and its inside diameter D of flexible transparent tube 1 12 (Figure 5) measuring about 1/4 to about 1/2 inch (about 0.64 to about 1 .27 cm), and ampoule 1 14 would be able to hold from about 1 to about 6 ml of liquid pH indicator. Obviously, test kit 1 10 may be made of any suitable size as needed for a particular purpose. The "standard" dimensions given above enable the nose 1 18d of test piece 1 18 to fit into a Schrader valve of the size typically used on small refrigerant units, as illustrated in Figure 7.

[0058] Figure 8 is an elevation view partly in cross section of another embodiment of a test piece usable in the present invention. Test piece 218 has a body section 218a which is circular in cross section and uniform in diameter except for frustoconical-shaped nose 218b which terminates in a recessed contact surface 218c. In this embodiment, body section 218a has a shroud 218d extending from about the longitudinal middle of body section 218a. Shroud 218d is of larger diameter than body section 218a and forms a circumferential shoulder 218e extending thereabout.

[0059] In use, test piece 218 would replace test piece 1 18 in a test kit that is otherwise identical or similar to the test kit illustrated in Figures 5 and 6. With this version of test piece 218, shroud 218d would fit over the external threads 122a of Schrader valve 122 (Figure 7) to thereby provide an enclosure 218g within which the refrigerant and its entrained lubricating oil would contact body section 218a and permeate the same to and through the top surface 218f thereof.

[0060] Other variations may be made to either test piece 1 18 or 218 or any other suitable test piece. For example, recessed contact surface 1 18e of test piece 1 18 and recessed contact surface 218c of test piece 218 may be hardened in any suitable way as by adding a hardening or reinforcing ingredient within the test piece adjacent the recessed contact surface, or by lining the exterior of the recessed contact surface with a suitable material. Further, some of the exterior surfaces of the test piece may be lined or otherwise treated to reinforce the test piece and/or confine and direct the flow of lubricant oil through the test piece to the top surfaces 1 18f and 218f of, respectively, test pieces 1 18 and 218. Of course, adequate pathways for the refrigerant gas or at least a significant portion thereof to escape from the test piece must be left unblocked.

[0061 ] Figure 9 shows another embodiment of the test kit of the invention in use. The components of Figure 9 which have the same structure and function as the components of the test kit illustrated in Figure 6 are identically numbered to the corresponding components in Figure 6 and are not further described. Figure 9 shows the test kit 1 10' after the closure cap 120 (Figure 6) has been removed from it and after test piece 1 18 thereof has been impregnated with the lubricant oil as illustrated in Figure 7. Consequently, the lubricant oil is exposed on the top surface 1 18f of test piece 1 18. In this embodiment, transparent tube 1 12' need not be flexible and is equipped with a removable seal comprising, in the illustrated embodiment, a hinged cap 1 19' which is movable between the open position shown in Figure 9 in solid line and a closed position shown in dash lines in Figure 9. Alternatively, removable seal 1 19' may comprise a snap-on or screw-on cap designed to close the exit- end of transparent tube 1 12'. A dispenser 126 is shown as depositing drop-wise a drop 1 16a of a liquid pH indicator onto the top surface 1 18f of test piece 1 18 to contact the lubricant oil disposed on top surface 1 18f. Dispenser 126 may be the type of dispenser which provides accurately reproducible drop sizes in order to assist the operator in dispensing an appropriate amount of liquid pH indicator or, preferably, dispenser 126 may contain a pre- measured amount of liquid pH indicator so that the entire contents of dispenser 126 are to be discharged. As with the liquid pH indicator dispersed by crushing the ampoule 1 14 of the Figures 5-6 embodiment, sufficient liquid pH indicator is to be dispensed in order to provide a discernible color change if the acid number of the tested lubricant oil is high enough, but not so much of the liquid pH indicator as to "drown" the lubricant oil and thereby make any color change difficult or even impossible to read.

[0062] When employing the test kit of the embodiment of the present invention illustrated in Figures 5-9 to carry out the test procedure, the closure cap 120 (Figure 6) is removed from the test kit, the test piece 1 18 is employed to depress the trigger pin 124 (Figure 7) of a Schrader valve to impregnate test piece 1 18 to the extent that lubricating oil is present at the top surface 1 1 Sf (Figure 5A) or 218f (Figure 8) of the test piece. When utilizing the test kit of Figures 5-8, transparent flexible tube 1 12 is then compressed to rupture frangible ampoule 1 14 so that the liquid pH indicator contacts lubricant oil on the top surface 1 1 Sf method differs only in that in lieu of crushing an ampoule, a removable seal 1 19', such as a hinged, snap-on or screw-on cap, is opened or removed so that a dispenser 126 may be used to deposit liquid pH indicator 1 16 into contact with the tested lubricant oil on top surface 1 18f (Figure 9) of test piece 1 18.

[0063] Referring now to Figure 10, another embodiment of the invention is shown in which parts which are identical to those of the embodiment of Figure 1 and which function identically are identically numbered and not further described. In the embodiment of Figure 10, flexible transparent tube 12 contains within it two frangible ampoules 314a and 314b within which are respectively disposed components of a liquid pH indicator 316a, 316b. In use, the embodiment of Figure 10 functions in a manner similar to that described above for the embodiment of Figure 1 except that flexible transparent tube 12 is squeezed as indicated by the four unnumbered arrows in Figure 10 to crush ampoules 314a and 314b. The embodiment of Figure 10 may be employed simply to supply additional liquid pH indicator in appropriately sized ampoules or the contents of ampoules 314a and 314b may differ from each other. For example, in some cases it is desired to add potassium hydroxide solution to the liquid pH indicator to attain a pH of about 8. While this does not appear to adversely affect the shelf life of the liquid pH indicator, some "color drift" has been noted in test samples. It is possible that this color drift is due to insufficient displacement of carbon dioxide from the ampoule, for example, by filling any empty head space in the ampoule with nitrogen, in case the potassium hydroxide or any other component desired to be added adversely affects the shelf life, the potassium hydroxide or other component may be contained in a separate capsule. Therefore, one of the capsules may contain the liquid pH indicator and the other may contain potassium hydroxide and/or other additives. By utilizing the two ampoules, these materials are admixed only at the time of use. The embodiment of Figure 10 further differs from that of Figure 1 in that entry-end cap 318a is flared outwardly into a pedestal-like configuration. This feature stabilizes the test kit 310 when it is placed in a vertical orientation on a flat surface. After collecting and testing the lubricating oil sample, test kit 310 may be set down and observed for any color changes. The pedestal-like configuration of entry-end cap 318a may comprise either a solid or hollow truncated cone as illustrated or the same effect could be provided by a plurality of legs extending outwardly or any other construction which provides the device with a footprint which is larger than that of the rest of the test kit and stabilizes it against turning over.

[0064] It will be apparent that any suitable dispenser may be used to control the amount of liquid pH indicator dispensed, such as an eye dropper or pipette. Another alternative which does not require use of the operator's judgment as to the amount of liquid pH indi-

18 cator to be added, utilizes packets containing a pre-measured quantity of liquid pH indicator. These packets are of the type sometimes used to dispense eyewash, nose drops or the like, and are usually supplied in sheets of individual packages which may be readily separated one from the other for use. The packets are formed with a necked-down portion which is cut or broken by the user. The packet is then squeezed to discharge the liquid through the necked-down portion. Such packets are a staple article of commerce and may be made from a composite of aluminum foil, polyolefin film and glossy paper or they may be made of molded plastic.

[0065] A phenolphthalein-TIA test liquid was adjusted to show a color change at an acid number of 0.05 mg KOH / gram sample. This will convert the indicator to a noticeably lighter purple or rose color or green or clear yellow liquid within several minutes. This color change signifies the presence of enough acid in a mineral oil lubricant to cause the onset of damage to the compressor of a refrigerant system. Stated otherwise, mineral oil lubricants can sustain acid numbers of less than 0.05 mg KOH before the onset of compressor damage. On the other hand, polyol ester oil lubricants can sustain acid numbers of less than 0.16 mg KOH / gram of sample before the onset of compressor damage. With an acid number of 0.16 mg KOH / gram of sample, the same adjusted phenolphthalein test liquid will cause the color change to be immediate and render the test liquid completely colorless. A strip of colors showing color changes representative of various acid numbers when using the liquid pH indicator in the test kit may be provided. This will enable the operator, whether experienced or not, to more easily determine whether at least the threshold level of acid is present in the oil residue, regardless of the type of lubricant oil tested. The threshold level of acid is the amount of acid which will prove deleterious to the refrigeration equipment whose lubricating oil is being tested. This enables ascertaining when the tolerable level of acid has been reached or exceeded. This technique allows the use of a single standard type test kit for any kind of present or future lubricant to test for any acid number over a significant range of acid numbers. The test kit of the present invention has been found to detect acid levels as low as 0.05 mg/gm acid number in mineral oil and as low as 0.16 mg/gm acid number in polyol ester oil and in alkylbenzene oil.

Example 1

[0066] A series of tests was carried out utilizing a liquid pH indicator comprising:

Phenolphthalein 1 1 .2 wt % of a 1 % solution in denatured ethyl alcohol Toluene 56.1 wt %

Isopropyl alcohol 30.0 wt %

The pH was adjusted by the addition of 2.7 wt % of a solution of 0.1 N KOH in isopropanol. [0067] Phenolphthalein was selected as a pH indicator because in the pH range of interest, the combination of phenolphthalein with the toluene and isopropyl alcohol solvent/carrier liquid provided the darkest hue of any other phenolphthalein test liquid tested. Of course, any other suitable pH indicators, such as bromothymol blue, or bromophenol blue, may of course be used. Similarly, other suitable solvent/carrier liquids such as xylene, chlorinated or brominated hydrocarbons, N-methyl pyrrolidone or ethyl acetate or suitable mixtures of two or more thereof may of course be used, in combination with suitable ones or combinations of the pH indicators.

[0068] Test and control lubricant oils in volumes of 0.5 ml were tested. The weight percents are based on the weight of the additive as a percentage of weight of the total mixture.

Test Lubricant Oils

A. Mineral oil containing 268 ppm by weight of oleic acid was prepared to provide an acid number of 0.053 mg / gm.

B. Polyol ester oil containing 177 ppm by weight of acetic acid was prepared to provide an acid number of 0.165 mg / gm.

C. Alkylbenzene oil containing 52 ppm by weight of acetic acid was prepared to provide an acid number of 0.049 mg / gm.

Control Lubricant Oils

A'. Unused mineral oil, no acid added.

B'. Unused polyol ester oil, no acid added.

C Unused alkylbenzene oil, no acid added.

Each test and control lubricant oil in 0.5 ml aliquots were mixed in separate, clean test tubes with 0.5 ml of the phenolphthalein-TIA test liquid, which had a dark purple color. The following results were attained after 30 seconds of reaction time with swirling of the mixed liquids, and then observing the color after 3 to 5 minutes of settling.

Test Lubricant Oil Result Control Lubricant Oil Result

A light rose A' No color change

B colorless immediately B' No color change

C colorless after 5 minutes C No color change Example 2

[0069] An indicator mixture sensitive to lower amounts of acidic oil is described here.

[0070] A series of tests was carried out utilizing a liquid pH indicator comprising:

Phenolphthalein (solid) 1 .00 wt %

Bromothymol blue (solid) 0.19 wt %

Toluene 61 .08 wt %

Isopropyl alcohol 32.00 wt %

The pH was adjusted by the addition of 5.73 wt % of a solution of 0.1 N KOH in isopropanol. Each test and control lubricant oil in 0.1 ml aliquots was added to an indicator test kit with an ampoule of 0.25 ml of the test liquid, which had a light navy blue color. The test kit was capped, the ampoule cracked and the kit shaken to mix the oil and the fluid. Within one minute the following results were obtained.

Test Lubricant Oil Result Control Lubricant Oil Result

A forest green A' Blue

B yellow-green B' Blue

[0071 ] When utilizing the test kits illustrated in Figures 4 and 9, the method differs only in that in lieu of crushing one or more ampoules, a removable end cap or seal, such as hinged, snap-on exit-end cap 18b' (Figure 4) or 1 19' (Figure 9) or a force-fit or screw-on cap versions thereof, is opened or removed so that a dispenser, such as dispenser 26, may be used to deposit liquid pH indicator 16 into contact with the lubricant oil residue to form the pool 17 of liquid reactants (Figure 4).

[0072] A test kit in accordance with the present invention may also include instructions and a color strip. The color strip correlates an acid number to different shades of the reacted liquid pH indicator which enables the operator to match the post-test color of the liquid pH indicator to facilitate assessing the acid number of the tested lubricating oil.

[0073] While the invention has been described in connection with certain specific embodiments thereof, it will be appreciated that numerous variations may be made to the described specific embodiments which variations nonetheless lie within the spirit and scope of the present invention.