U.S. patent application number 10/900628 was filed with the patent office on 2005-01-13 for sensing unit for detecting refrigerant leak sealant additive.
This patent application is currently assigned to Neutronics, Inc.. Invention is credited to Anderson, J. Douglas.
Application Number | 20050005680 10/900628 |
Document ID | / |
Family ID | 31996985 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050005680 |
Kind Code |
A1 |
Anderson, J. Douglas |
January 13, 2005 |
Sensing unit for detecting refrigerant leak sealant additive
Abstract
A device for determining the presence or absence of refrigerant
leak sealant within the refrigerant charge of air conditioning
systems or stores is described. A sensing unit having a
seal-forming surface is wetted and placed in fluid communication
with a refrigerant access port of the air conditioning system. A
depressor opens the refrigerant port and refrigerant begins to flow
through the sensing unit. If any leak sealant is present in the
refrigerant charge, a sealant plug begins to form on the
seal-forming surface and reduces the flow rate of the refrigerant
through the sensing unit, thereby indicating the presence of the
sealant. Refrigerant charges that do not contain a leak sealant
will flow through the sensing unit at a substantially constant
rate, indicating the absence of sealant.
Inventors: |
Anderson, J. Douglas; (West
Chester, PA) |
Correspondence
Address: |
DRINKER BIDDLE & REATH
ONE LOGAN SQUARE
18TH AND CHERRY STREETS
PHILADELPHIA
PA
19103-6996
US
|
Assignee: |
Neutronics, Inc.
|
Family ID: |
31996985 |
Appl. No.: |
10/900628 |
Filed: |
July 28, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10900628 |
Jul 28, 2004 |
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10348265 |
Jan 21, 2003 |
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6810714 |
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60411193 |
Sep 17, 2002 |
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Current U.S.
Class: |
73/40 |
Current CPC
Class: |
F25B 45/00 20130101;
G01M 3/042 20130101; F25B 2345/006 20130101; G01N 7/10
20130101 |
Class at
Publication: |
073/040 |
International
Class: |
G01M 003/04 |
Claims
What is claimed is:
1. A sensing unit for use with a device for detecting the presence
or absence of a leak sealant additive in an air conditioning
charge, the sensing unit comprising: an inlet for admitting
refrigerant, an outlet for exhausting the refrigerant; a passage
between the inlet and the outlet; and a seal-forming surface within
the passage on which leak sealant additive can form a sealant plug
to at least partially restrict refrigerant flow from the inlet to
the outlet.
2. The sensing unit of claim 1 wherein the seal-forming surface
comprises a porous insert between the inlet and the outlet.
3. The sensing unit of claim 2 wherein the porous insert comprises
sintered metal.
4. The sensing unit of claim 1 wherein the passage comprises a
machined orifice and wherein the seal-forming surface comprises a
surface adjacent the machined orifice.
5. The sensing unit of claim 1 wherein the seal-forming surface
defines a flow restrictor that allows less than five percent of the
refrigerant charge to pass in three minutes.
6. The sensing unit of claim 1 wherein the seal-forming surface
defines a flow restrictor that limits refrigerant flow to between
about 100 cm.sup.3/min and about 1000 cm.sup.3/min from a
refrigerant source at 60 to 200 psig.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a division of co-pending
application Ser. No. 10/348,265, filed Jan. 21, 2003, the entire
disclosure of which is incorporated herein by reference, which
claimed priority from U.S. Provisional Patent Application No.
60/411,193, filed Sep. 17, 2002. The present application claims
priority from both the Ser. No. 10/348,265 application and the
60/411,193 provisional application.
FIELD OF THE INVENTION
[0002] The present invention relates to a device and method for
identifying the presence or absence of a leak sealant additive in
air conditioning system refrigerant charges, preferably but not
exclusively for the purpose of identifying potential damage risk to
air conditioning service, repair, diagnostic or other
equipment.
BACKGROUND OF THE INVENTION
[0003] Government regulations in the United States, and in many
other countries, require the control of refrigerant releases during
air conditioning system service and repair due to the potential
damaging effects of fluorocarbon refrigerants to atmospheric ozone
levels. Fluorocarbon refrigerants, for example R12, R22, R500 and
R502, are suspected of presenting an environmental threat due their
potential to deplete the earth's atmospheric ozone layer.
Production of these refrigerants has been or is being discontinued
by various manufacturers in accordance with the Montreal
Protocol.
[0004] Alternative refrigerants, such as R134a (tetrafluoroethane)
for example, are now being utilized that will lessen, but will not
totally remove, the potential for atmospheric ozone depletion.
[0005] Air conditioning technicians use various service and
diagnostic equipment designed to limit the release of all
refrigerants to the environment. Such equipment includes, but is
not limited to, refrigerant identification analyzers, refrigerant
recovery equipment, refrigerant recycling equipment, and
refrigerant charging equipment.
[0006] Numerous studies of air conditioning servicing and
discussions with air conditioning repair technicians indicates that
the single largest contributor to refrigerant releases to the
atmosphere is air conditioning system leaks. Air conditioning
system leaks are also the leading cause of air conditioning system
malfunctions in the industry. Air conditioning system leaks
contribute to poor air conditioning system performance, increased
customer complaints, increased costs to customers due to
refrigerant charge replacement, and environmental damage. Costs of
refrigerant charge replacement are ever increasing as the cost of
original and alternative refrigerants increases.
[0007] To lessen the affect of air conditioning system refrigerant
leaks upon the customer and the environment, several manufacturers
have developed air conditioning system leak sealant additives.
These additives come in a variety of formulations from numerous
manufacturers. Examples of such leak sealant additives are Super
Seal Pro.TM. from Cliplight Manufacturing Company of North York,
Ontario, Canada; CRYOseal.TM. Self-Sealing Kits from Cryo-Chem
International of Brunswick, Ga., USA; Keep-It-Kool.TM. from
Mobilair 2000 of Toronto, Ontario, Canada; and R-134a Leak Stop.TM.
from Technical Chemical Company of Cleburne, Tex., USA, to name a
few. Additionally, virgin refrigerants that contain a leak sealant
additive are now available directly from refrigerant
manufacturers.
[0008] All of these leak sealant additives are designed to seal air
conditioning leaks in air conditioning metal components.
Specifically, the additives are designed to seal leaks in metal
components such as evaporator cores where access is difficult with
conventional leak detectors. The additives are typically added to
the refrigerant charge as a one or two part liquid and are
distributed throughout the air conditioning system via refrigerant
circulation by the system compressor. When a leak develops in an
air conditioner metal component, the leak sealant additive will be
delivered to the leak point by the escaping refrigerant and produce
a permanent seal over the leak path, typically in one of two ways.
The most common method of seal formation involves the exposure of
the sealant to moisture. Moisture is provided by the rapid
expansion of refrigerant gas through the leak path, which provides
cooling and condensation of atmospheric water vapor at the leak
point. Moisture can also be supplied by the condensation that is
typically present on all air conditioning system evaporator cores.
The additive will then combine with the condensed moisture at the
leak to form a permanent seal over the leak path. The other method
of seal formation involves the combination of condensed atmospheric
water vapor, atmospheric oxygen, and the additive to form a
permanent seal over the leak path. Typically, additives that
require only exposure to moisture will form a seal on the interior
surface of the leak path. Additives that require exposure to
moisture and oxygen will typically form a seal within or on the
exterior of the leak path. The presence of a leak sealant additive
can reduce the environmental impact of refrigerant venting, reduce
customer complaints, and limit air conditioning system performance
degradation.
[0009] However, leak sealant additives can pose difficulties for
air conditioning technicians when service is performed upon an air
conditioning system that contains a leak sealant additive. The
additives will be directly exposed to the diagnostic equipment upon
connection to the air conditioning service ports. Since the
diagnostic equipment may contain atmospheric water vapor and
atmospheric oxygen, the formation of a permanent seal by the
additive may be initiated within the equipment itself. Thus, many
air conditioning diagnostic tools can be damaged through the
clogging of sensing devices, solenoid valves, hoses, gauges, vacuum
pumps, etc., by sealant additives. Therefore, air conditioning
technicians and manufacturers of air conditioning diagnostic
equipment are searching for devices that will either identify the
presence of leak sealant additives or provide for their removal to
protect expensive diagnostic equipment.
[0010] Attempts are currently underway to provide for leak sealant
additive removal through filtration. Filtration may involve the
removal of refrigerant oil or a liquid-liquid separation filter.
Removal of the refrigerant oil from the refrigerant may not serve
to totally remove the leak sealant additive since the additives
typically are disbursed throughout the refrigerant liquid and vapor
phases as well as the refrigerant oil. Liquid-liquid separation may
provide an effective method to remove the additives but may require
unacceptably high costs to the air conditioning technician. A
method of detecting the presence of the leak sealant additive
through non-dispersive infrared radiation (NDIR) technology has
been developed by the assignee of the present application,
Neutronics Incorporated of Exton, Pa., USA. While NDIR technology
has provided promising results, it can be expensive.
[0011] The present invention utilizes the complete or partial
formation of a seal by leak sealant additives and provides a device
and method for detecting the presence of sealant additives within
an air conditioning system refrigerant charge. The invention is
inexpensive, fast, limits refrigerant loss, and easy to use.
SUMMARY OF THE INVENTION
[0012] The present invention provides a fast, easy, and inexpensive
device and method for detecting the presence of a leak sealant
additive within an air conditioning system refrigerant charge or
within refrigerant stores. The device is capable of detecting any
leak sealant additive in any refrigerant type.
[0013] One feature of the present invention is the use of a sensing
unit having a passage with a calibrated leak path through which
refrigerant can flow. The sensing unit includes a seal-forming
surface on which any leak sealant additive can quickly form a seal
in the presence of water and/or oxygen to at least partially
occlude the passage. The sensing unit is used in combination with a
coupler for engaging and opening a refrigerant system service port
and a flow indicator for detecting the rate at which refrigerant
gas flows through the sensing unit.
[0014] In use, the sensing unit can be wetted with ordinary water
and connected between the service coupler and flow indicator to
form a test rig. The test rig is then connected directly to the air
conditioning system or refrigerant storage cylinder service port.
Refrigerant from the air conditioning system or storage system will
flow through the coupler, sensing unit, and flow indicator. If the
refrigerant contains a leak sealant additive, the flow indicator
will show a reduction or complete stoppage of refrigerant flow over
time as the sealant begins to seal the leak path in the sensing
unit. If the refrigerant does not contain a leak sealant additive
the flow indicator will indicate a substantially constant
refrigerant flow rate over time. Thus, the change in refrigerant
flow rate through the sensing unit indicates the presence or
absence of a leak sealant additive within the tested refrigerant.
If refrigerant flow rate diminishes or ceases totally, then a leak
sealant additive is present. Conversely, if refrigerant flow rate
remains constant, then no leak sealant additive is present in the
refrigerant.
BRIEF DESCRIPTION OF THE FIGURES
[0015] Reference is now made to the figures in which:
[0016] FIG. 1 shows a first embodiment of a test rig according to
the present invention, suitable for use with a typical automotive
R134a air conditioning system;
[0017] FIG. 2 shows a second embodiment of a test rig according to
the present invention, suitable for use with a typical automotive
R12 air conditioning system;
[0018] FIG. 3 is a cross-sectional view of a first embodiment of a
sensing unit according to the present invention;
[0019] FIG. 4 is cross-sectional view of a second embodiment of a
sensing unit according to the present invention; and
[0020] FIG. 5 is a cross-sectional view of a test rig in use while
fitted with the sensing unit of FIG. 3.
DETAILED DESCRIPTION OF THE DRAWINGS
[0021] In the Figures, in which like numerals indicate like
elements, there are shown test rigs and sensing units according to
the present invention. FIG. 1 shows a first embodiment of an
assembled test rig 10. The test rig 10 is suitable for use with a
R134a-based automotive air conditioning system. As is shown by
example below, the test rigs of the present invention can be
tailored for the specific requirements of other refrigerant-based
air conditioning systems through the use of alternative materials,
alternative connection components or any other specific
requirements of the specific refrigerant-based air conditioning
system. The test rigs can be used to detect the presence of a leak
sealant additive in virtually any air conditioning system or
refrigerant store, including those having halogen-based,
fluorocarbon-based, or other non-halogen, non-fluorocarbon based
refrigerants and compounds, such as propane, ammonia, carbon
dioxide, etc. In use, the test rig 10 is connected to the liquid or
high-side port of the air conditioning system or refrigerant store
for the extraction of a small portion of the total refrigerant
charge.
[0022] Test rig 10 includes a coupler 12, a sensing unit 14, a
transfer tube 16 and a flow indicator 18. (The sensing unit 14 is
shown in FIG. 3 and described below.) The coupler 12 can be a
conventional automotive R134a high-side service coupler 20 and a
quick-disconnect fitting 22. The R134a high-side service coupler 20
is sized to connect to the high-side or liquid port of R134a-based
air conditioning systems or stores and contains a depressor device
that will open such service port valves. The R134a high-side
service coupler 20 is a commercially available component known to
those skilled in the art. Quick-disconnect fitting 22 is a device
that permits easy connection of sensing unit 14 to the coupler 12
and will provide the passage of refrigerant from the coupler 12 to
the sensing unit 14. Quick-disconnect fitting 22 is also a
commercially available component well known to those skilled in the
art. Service coupler 20 and quick-connect fitting 22 can be
threaded and screwed together, welded together, or joined by other
sealing-type connections.
[0023] Transfer tube 16 preferably comprises flexible tubing,
suitable for exposure to the specific refrigerant type, that will
transfer refrigerant escaping through sensing unit 14 to flow
indicator 18. The tube 16 can be formed from flexible neoprene
tubing for most refrigerant types. Flow indicator 18 can be a flow
meter capable of detecting flow rate in a range suitable for the
specific type of air conditioning system. If automotive air
conditioning systems are to be tested, the flow indicator 18 should
be responsive to flow rates of between about 100 cubic centimeters
per minute (cm.sup.3/min) to about 1000 cm.sup.3/min (about 0.2 to
2 cubic foot per hour). Preferably, the flow indicator 18 is a
variable area flow meter having an inlet for connecting to the tube
16 and an indicator ball disposed within a slightly tapered tube.
Like the tube 16, the flow indicator is preferably formed using
materials capable of withstanding exposure to the specific
refrigerant type. However, more economical materials, such as
polycarbonate, can also be used.
[0024] A second embodiment of a test rig 110 is shown in FIG. 2.
Test rig 110 is adapted for use with an R12-based automotive air
conditioning system. Test rig 110 includes a coupler 112, a sensing
unit 114, a transfer tube 116 and a flow indicator 118. The coupler
112 can be made using a conventional R12 high-side service coupler
120 and a quick-disconnect fitting 122. The R12 high-side service
coupler 120 is sized to connect to the high-side or liquid port of
an R12-based air conditioning system or store and contains a
depressor device that will open such service port valves. Like the
R134a coupler of FIG. 1, such R12 high-side service couplers are
commercially available and well known to those skilled in the art.
Quick-disconnect fitting 122 is analogous to element 22 of FIG. 1
and similarly permits easy connection of sensing unit 114 to the
coupler 112 and provides for the passage of refrigerant from the
coupler 112 to the sensing unit 114. Quick-disconnect fitting 122
can be threaded to mate with the R12 high-side service coupler 120.
Such quick-disconnect fittings are well known and commercially
available. Transfer tube 116 and flow indicator 118 are also
similar to their analogous components of the first embodiment.
[0025] The sensing unit 14 and sensing unit 114 will now be
described with reference to FIGS. 3 and 4. The sensing unit 114 is
interchangeable with sensing unit 14. Therefore, sensing unit 14
can be used in place of sensing unit 114 in the test rig 110. Also,
sensing unit 114 can be used in place of sensing unit 14 in the
embodiment of FIG. 1. Sensing unit 14 and sensing unit 114 are
preferably disposable, it being understood that a sensing unit
could be reused after a test (more fully described below) if no
leak sealant additive is found within the tested system. However,
reuse of a sensing unit is not recommended because if used
repeatedly the sensing unit could become clogged with oil, dyes, or
other materials commonly found around air conditioning systems.
[0026] A preferred embodiment of sensing unit 14 is shown in FIG.
3. The sensing unit 14 includes a tubular body 30 that may be made
of any suitable material. Brass and molded plastic are two such
materials. The tubular body 30 includes an open quick-disconnect
end 32 with a recess 34 designed to mate with the quick-disconnect
fitting 22 of the test rig 10. Opposite the quick-disconnect end 32
is an open tube stub end 36 with ribs 38 for attaching the transfer
tube 16. The tubular body 30 is hollow and defines a passage 40
extending between an inlet 42 at the quick-disconnect end 32 and an
outlet 44 at tube stub end 36. The body 30 also has a circular
shoulder 46 extending into the passage 40, which acts as a set for
a sintered metal plug 48.
[0027] The sintered metal plug 48 provides a calibrated leak path
through the passage 40. The sintered metal plug 48 can be formed
from stainless steel, brass, or other suitable materials. The
sintered plug 48 is porous and defines a plurality of flow passages
through it to permit an adequate amount of refrigerant to flow
through the plug 48 for reliable detection, yet limit the amount of
refrigerant that will be released to the environment. A sintered
metal plug sized for a 600 cm.sup.3/min flow rate when exposed to a
source of 100 psig of nitrogen gas and vented to one atmosphere is
suitable. Sintered plugs with flow rates within a tolerance of
fifteen percent of 600 cm.sup.3/min are presently preferred. The
sintered plug 48 can be installed into the passage 40 of the body
30 using a guided hand-operated press. However, the sintered plug
48 tends to compress when so installed, decreasing its porosity,
and exhibiting a lower rate of through flow. Therefore, an
uninstalled sintered plug with a flow through rate greater than 600
cm.sup.3/min is used to form the sensing unit 14. It has been found
that uninstalled sintered plugs with flow rates of about 750
cm.sup.3/min are suitable. Sintered plugs are commercially
available from Mott Corporation of Farmington, Conn. Such plugs,
when installed and compressed, provide the desired flow rate of
about 600 cm.sup.3/min. This flow rate specification will provide
adequate refrigerant flow from a 60 to 200 psig source for
detection in the 100 cm.sup.3/min to 1000 cm.sup.3/min range to
deliver adequate leak sealant additive to initiate a sealing
reaction within or on the sintered plug and limit refrigerant loss
to less than five percent, and preferably less than three percent,
of the total refrigerant charge of a typical automotive air
conditioning system during a three minute testing period. Thus, the
sintered plug 48 provides both a flow-restricting passage through
its internal passageways, and also a seal-forming surface on which
any leak sealant additive that may be present can form a sealant
plug to fully or partially occlude the passage 40. As used herein,
the term "seal-forming surface" means any surface on which a leak
sealant additive can consistently begin forming a sealant plug to
at least partially reduce refrigerant flow rate through the sensing
unit. Such a surface is adjacent to the flow path and has a large
enough surface area to allow the sealant plug to begin forming
before five percent of the refrigerant charge within the air
conditioning system has been vented.
[0028] In order to minimize the chance of unintended clogging, it
is recommended that the sensing unit 14 be provided in a sealed bag
or that both the inlet 42 and outlet 44 be provided with removable
seals. The sensing unit 14 should remain sealed until immediately
prior to use. In use, refrigerant gas will enter the passage 40
through inlet 42, travel through passage 40, and come to sintered
plug 48. The circular shoulder 46 of the body 30 prevents pressure
of entering refrigerant from dislodging the sintered plug 48.
Refrigerant then passes through sintered plug 48, continues through
passage 40, and exhausts through outlet 44. In the presence of
moisture, and in some cases the presence of oxygen, refrigerant
that contains a leak sealant additive will begin to form a seal on
or within the flow passages in sintered plug 48, thereby reducing
the total flow rate of refrigerant through sensing unit 14.
[0029] FIG. 4 shows a second embodiment of a sensing unit 114.
Sensing unit 114 has a tubular body 130 that uses a core 150 with a
machined orifice 148 as the calibrated leak path in passage 140. In
the sensing unit 114, the seal-forming surface is the interior
surface of the core 150 adjacent to the machined orifice 148. The
machined orifice 148 is sized to provide enough refrigerant flow
for ease of flow detection, yet limit the amount of refrigerant
that will be vented to the environment. The machined orifice 148 is
sized in the 50 to 100 micron (0.002 to 0.004 inch) diameter range.
This diameter specification will provide adequate refrigerant flow
from a 60 to 200 psig source for detection in the 100 cm.sup.3/min
to 1000 cm.sup.3/min range, deliver adequate leak sealant additive
to initiate seal formation on the core 150 or within the orifice
148, and limit refrigerant loss to a maximum of five percent, and
preferably three percent, of the total refrigerant charge of a
typical automotive air conditioning system during a time period of
three minutes. The sensing unit 114 includes additional features
that are similar to the analogous elements of the sensing unit 14
of FIG. 3. These features include an inlet 142 at a
quick-disconnect end 132 with recess 134, and an outlet 144 at an
open tube stub end 136 having ribs 138.
[0030] In use, refrigerant gas enters the sensing unit 114 through
inlet 142, travels through passageway 140 and comes to the core 150
with machined orifice 148. Refrigerant then passes through the
machined orifice 148, and exhausts through the outlet 144. In the
presence of moisture, and in some cases the presence of oxygen,
refrigerant that contains a leak sealant additive will begin to
form a seal on the core 150 at the inlet of or within the machined
orifice 148, thereby reducing the total flow rate of refrigerant
through sensing unit 114.
[0031] The use of the sintered metal plug 48 in place of the core
150 with the orifice 148 is preferred. The sintered metal plug 48
provides multiple small diameter leak paths that are more easily
sealed by the leak sealant additive compared to a larger single
orifice hole. Additionally, the sintered metal plug 48 is less
prone to clogging by materials other than leak sealant additives
such as moisture desiccants, particulate matter, refrigerant oils,
leak tracer dyes, etc. Therefore, if a single orifice sensing unit,
such as sensing unit 114, is used, it is recommended that a
filtering device upstream of the sensing unit 114 be employed to
prevent accidental clogging. Alternatively, sensing unit 114 can be
outfitted with a screen, between the inlet 142 and the core 150.
The screen could be filter paper, mesh or sintered metal of an
appropriate configuration to filter particulate, while not
affecting the flow through rate of the sensing unit 114. For
example, if sintered metal is used as the screen, it should have a
rating of about 50 to 100 microns, thereby preventing particulate
from clogging the orifice 148, while not affecting the rate of
refrigerant flow through the sensing unit 114 if a leak sealant
additive begins to form a sealant plug on the screen. The flow rate
through the sensing unit 114 is instead governed by the calibrated
orifice 148 and any sealant plug formed on its adjacent
seal-forming surface.
[0032] The method of the present invention will now be described
with reference to FIG. 5, which shows a test rig 210 fitted with a
sensing unit 14 and connected to a typical R12-based air
conditioning system or refrigerant store service port 302. Similar
operation is achieved using test rig 10 for R134a based air
conditioning systems or test rig 110 fitted with sensing unit 114,
the differences in the seal-forming surfaces and refrigerant
flow-restricting passages between the two embodiments having
already been described. Before connecting test rig 210 to the
service port 302, sensing unit 14 is wetted on the inside of both
openings. As used herein, wetting is meant to include any method of
introducing moisture to at least one inside surface of a sensing
unit, preferably between the flow-restricting passage and the
inlet, such as by directly pouring or injecting ordinary tap water
into an open end of the sensing unit 14, immersing the entire
sensing unit in water, or introducing a moist article. Excess water
can then be removed from the interior of the sensing unit 14 by
shaking it several times to leave a trace of moisture droplets 300.
The introduction of moisture into the sensing unit provides an
accelerator for seal formation during testing should a leak sealant
additive be present in the test refrigerant.
[0033] After wetting, the sensing unit 14 is connected to
quick-disconnect fitting 222 of test rig 210. Quick-disconnect
fitting 222, like its analogous elements in the first two
embodiments, is commercially available. The fitting 222 includes a
body 260, sealing o-ring 262, retaining balls 264, and coupler
actuator 266. A transfer tube, such as transfer tube 16 of FIG. 1,
can connect the tube stub 36 to a flow indicator. The test rig 210
is then connected to the air conditioning system or refrigerant
store service port 302, which has an access valve 304. A high-side
service coupler 220 of the test rig 210 has an elastomeric seal 270
capable of withstanding exposure to refrigerant, a valve depressor
272, containment cup 274, tube 276, body 278, and connection nut
280. Valve depressor 272 depresses service port valve 304 while
seal 270 seals port 302, preventing refrigerant from escaping to
the environment at the connection.
[0034] Once valve 304 is actuated, refrigerant flow will travel in
the direction of arrow A through coupler 212 (through service
coupler 220 and quick-disconnect fitting 222), through sensing unit
14, through a transfer tube and through a flow indicator (such as
those shown in FIGS. 1 and 2) where an indication of initial
refrigerant flow will be displayed. If the refrigerant contains no
leak sealant additive, the flow meter will indicate a constant flow
rate throughout the duration of the test. If the refrigerant
contains a leak sealant additive, the additive will combine with
the water droplets 300, and in some cases the ambient oxygen, to
begin to form a sealant plug on the seal-forming surface of the
sensing unit 14 (on or in the sintered metal plug 48). If a sealant
plug forms, the flow indicator will indicate a flow reduction or a
complete loss of flow during the test period. It is expected that a
three-minute test period is more than adequate to detect a
reduction of flow rate in the presence of a leak sealant additive.
Over a three-minute period, an observed reduction of from 40 to 100
percent of the original initial flow rate can be expected if leak
sealant additive is present in the refrigerant.
[0035] Once the flow has been established as constant, diminishing
or absent, the test rig 210 is removed from the air conditioning
refrigerant access port 302. The limited time period of testing,
together with the limited flow rate through the sensing unit 14,
limits the amount of refrigerant charge vented to the
atmosphere.
[0036] After testing has been completed, sensing unit 14 can be
removed from coupler 212 and the transfer tube and discarded. A new
sensing unit 14 can be installed onto coupler 212 and to the
transfer tube to prepare the test rig 210 for another test.
[0037] It should be again noted that the test rig 210 depicted in
FIG. 5 would find use primarily in automotive R12 refrigerant-based
air conditioning systems. Modification of service coupler 212 can
enable test rig 210 to be connected on other air conditioning
systems that contain other refrigerant types, for example R134a,
R22, R500 and R502. FIG. 1 is an example of a R134a test rig that
would be used on R134a based air conditioning systems.
* * * * *