CA1325462C - Method and apparatus for leak testing a fluid containing chamber - Google Patents
Method and apparatus for leak testing a fluid containing chamberInfo
- Publication number
- CA1325462C CA1325462C CA000593212A CA593212A CA1325462C CA 1325462 C CA1325462 C CA 1325462C CA 000593212 A CA000593212 A CA 000593212A CA 593212 A CA593212 A CA 593212A CA 1325462 C CA1325462 C CA 1325462C
- Authority
- CA
- Canada
- Prior art keywords
- bubbles
- chamber
- liquid
- predetermined
- panel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
- G01M3/06—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point by observing bubbles in a liquid pool
- G01M3/10—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point by observing bubbles in a liquid pool for containers, e.g. radiators
Abstract
ABSTRACT OF THE DISCLOSURE
A method and apparatus is disclosed for leak testing a fluid containing chamber wherein the chamber is pressurized with a gas and is submerged in liquid. The bubbles of gas rising from the submerged chamber are directed past a predetermined location which is adjacent to a photoelectric detector. The electrical signals from the photoelectric detectors are counted and when the number bubbles exceeds a predetermined number a fault signal is activated indicating a leaking container. By grouping a number of adjacent photocells into a predetermined set, the apparatus can discriminate between random bubbles rising from the chamber as it is submerged, and a number of bubbles all originating from a given location.
A method and apparatus is disclosed for leak testing a fluid containing chamber wherein the chamber is pressurized with a gas and is submerged in liquid. The bubbles of gas rising from the submerged chamber are directed past a predetermined location which is adjacent to a photoelectric detector. The electrical signals from the photoelectric detectors are counted and when the number bubbles exceeds a predetermined number a fault signal is activated indicating a leaking container. By grouping a number of adjacent photocells into a predetermined set, the apparatus can discriminate between random bubbles rising from the chamber as it is submerged, and a number of bubbles all originating from a given location.
Description
- " 11 32~4~2 METHOI) AND APPARATUS EOR LF~K TESTING
A ~UID CONl'AINING CHA~ER
I~ACKG~UND 0~ E INV~TICN
This invention relates to a leak detection apparatus and more particularly to an automated means for detecting leaks via liquid imnersion testing.
Numerous cor,~onents are rnanufactured which must neet a standard for a "leak tightness". Leak tightness is a relative term, as nothing can ever by completely free of leakage. A balance ~mst be made between the increasing cost of finc7ing smaller and smaller leaks and their importance to the functioning of the unit over its useful life. Leak tlghtness is the practical lealcage that is acceptable under norrnal operating circumstances.
Components which require some degree of leak tightness, for example, include fuel ~nks, radiators, fuel system components, water pumps, refrigeration components, heater cores, torque convertors, hydraulic and pnewnatic components etc. me acceptable leakage w~ll depend upon the usage of the co~fponent with respect to the type of fluid which rnust be contained, i.e. a gas or a liquid, and whether or not the contents will be pressurized.
Several leak detection methods are comnonly used in industry.
Eac~h rnethod has its awn advantages, limitations and sensitivity range.
As a result, not all rnethods are useful for every application. me correct choice of the leak detection ll~thod should optimize co~t, sensitivity and reliability of the test.
Liquid imnersion testing is one of the oldest doc~nented methods used to detect leaks. Liquid i~ersion testing operates on the basis of ' :
~,, ~, ' .
', ' ' ' " ~
~3254~2 a differential pressure at the leak creating a ~low of a gas from within the component to the liquid outside. The part being teste~ is pressurized with a gas and then immersed in a liquid medium, generally water. The gas escaping the pressurized component produces one or n,ore bubbles in the liquid which then rise to the surface of the water. m e com~onent being tested is allowed to ren~in in the liquid for a period of time while the lia,uid test nedium is examined for the presence of bubbles. The location of bubbles indicates the location of a leak and the frequency and size of the bubbles can be used to estimate the leakage rate.
Liquid immersion testing has several advantages which include, low equipment cost relative to other methods, location of the leak can be determined, the ea,uipment can easily be made durable enough for factory floor applications, and various size and shape components can be tested utilizing one test apparatus.
The prin~ry disadvantage with liqvid in~ersion testing is the require~ent of an operator to visually inspect the water for bubbles of leaking gas. This adds subjectivity to the test and, in addition, research has shown that an operatorls ability to accurately identify leaks decreases during the course of a typical eight hour work shift.
Accordingly, it is an object of this invention to provide a liquid in ~ rsion leak testing apparatus which includes an automatic neans for detecting the presen oe of bubkles of gas leaking from the component being tested.
~ t is an advantage of this invention that a low cost liquid immersion testing apparatus can be equipped with an automatic sensing .
.
, 1325~62 means which provides increased accuracy in detecting leaks without significantly increasing the cost of the device.
SUMMA~Y OF THE INVENTICN
~ he leak detection apparatus of this invention employs a tank for submerging the comp3nent to be tested in a liquid test medium, typically water. Other liquids may be used as long as they are compatible with the test apparatus and the component ~eing tested. Automatic identification of bubbles is accomplished by using a photoelectric detector such as the Clairex Cl-703L photocell. To provide complete coverage of the surface area above the component being tested, a plastic channeling device is used to direct the bukbles rising in the liquid along a predetermined path which passes beneath the photocell.
It is contemplated that the channeling device be constructed of a transparent plastic material such as acrylic which on its lower side has a plurality of ridges and grooves extending longitud m ally of the acrvlic panel. The panel is positioned in the liquid above the canponent being tested and is inclined along its length such that bubbles rising from the component wnll impact the acrylic panel, move upward to one of the grooves in the underside of the panel and travel along the gro~ve to the upwardly inclined end of the acrylic panel. A photocell is positioned above each groove at the upper end of the panel.
The number of photocèlls used can range fro~ two or thr~e to as many as lifty to provide coverage to the entire component being tested.
By increasing the number o~ photocells, the corresponding area of the co~ponent being tested by each detector is reduced, thereby increasing the accuracy of leak localization.
132~2 An electrical circuit, which may or may not include a computer, can be us~d to count the number of bu~bles detected by the photocells and a fault signal can be activated when the number of bubbles counted exeeds a predetermined number, thereby indicating a leaking component.
m e system can detect gxoss leaks to very small leaks having a leakage rate of 10 4 cc/sec. The test time must be increased as ~ensitivity is i~creased bo allow a bubble to be formed which is large enough ~o overcome the surface tension holding the bubble to the component surfa oe .
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.
ERlEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevation view of a immersion leak test apparatus employiny photoc~lls to automatically detect t e presence of bubb~es according to this inventivn;
Figure 2 is an end view as seen in the direction of arrow 2 of the channeling devioe used to direct the bubbles past the photocells;
Figure 3 is an enlarged side view of th2 upper end of the channeling devioe ;
Figure 4 is a schematic of the electric~l circuit used to count the bubbles and activate the fault signal;
Figure 5 is a schematic of a alternat~ve circuit to count bubbles which discriminates between attached bubbles formed when the component is submerged and leak bubbles; and ~32~2 Figure 6 is a side elevation view of a portion of the apparatus of Fisure 1 in which the tank is sealed and a partial vacuum is created in the tank abcve the water.
L~-lAILED DESCRIPTION OF THE INVENTION
_.
With reference t3 the drawings, an automated liquid immersion leaking apparatus 1~ is illustrated in Figure 1. The leak test apparatus includes a liquid holding ta~k 12 which oontains a quantity of water to a level indicated at 16.
Positioned above the water holding tank 12 is a cage like test fixture 18 which is used for lowering and raising a component 20, in this case a fuel tank, into and out of the water in the holding tank 12. The fixture 18 includes a base support member 21 upon which the fuel tank is positioned, vertic~l frame members 22 auld an upper cross member 23.
Extending upward from the cross member 23 is a support cylinder 24 which is used for raising and lowering the fixture 18 into and out of the water.
Positioned below the upper cross member 23 is an intermediate cross member 25 which supports a cylinder 26 for sealing the fuel sender opening in the top surface of the fuel tank. Another cylinder (not ~hown) is used for sealing the uel filler neck opening of the fuel t~nk.
In addition~ one or more other cylinders may be required for holding the fuel tank down against the base me~ber 21 while conducting the test.
Cylinder 26, In addition bo sealing the fuel sender opening, also includes a conduit for providing air pressure to the interior of the f~el tank once it is sub~erged in the water. The component 20 can be either .
: '.: , : ' , .. ..
. , , ;;
` 1325~2 -nanually or automatically positioned on the base 21 when the fixture 18 is in the raised position as shown in Figure 1.
A~so extending downward from the interme~iate cross member 25 are support brackets 28 which support acrylic panels 30 inclined relative to horizontal. Panels 30 are used to deflect any bubbles of air rising from the fuel tank past one of a plurallty of photocells positioned at the upper end of the acrylic panels 30 as will be discuss~d m detail below.
The panels 30 are shown in a position in which only a portion of the welded seam of ths fuel tank is being testsd for leaks. Additional panels 30 and photo oe lls can be positioned over other areas of the fuel tank 20 to provide leak testing of additional portions of the fuel tank.
Figure 2 is a view in the direction of arrow 2 of Figure 1 and illustrates the detail of the upper end 38 of the panels 30. The bottom surfa oe of the acrylic panel 30 is corrugated to form a plurality of evenly spaced ridges 32 and grooves 34 hav m g flat inclined surfaoes 36 extending between each ridge and groove. The ridges are spaced approximately two inches from each other. At the grooves 34, the surfaces 36 do not form a sharp corner but form a curved transition having a radius of approximately 1/4 inch The angle between adjacent surfaces 36 is approximately 135. The angle of inclination of the panel 30 in the water is approximately 20-30~ The angle of the panel 30 must be large enough to allow the bubbles to continuing rising in the grooves 34 However, as this angle is increased, the depth of the tank 12 must also be increased tD enable complete submerging of the panel 30 in the tank.
The bottom surface of the panel 30 must have a proper surface finish to prevent bubbles from sticking to the panel. ~he surface must : `
, .
,, .,, .. ~, .. :. . . ... .
~32~4~2 permit "wetting" or the formation of a film of water when the panel is out o~ the water. A surface that will not "wet" will forrn droplets of water on its surface as opposed to a water film. A smooth acrylic panel will not "wet". Wh~l an air bubble contacts a smooth panel, the bubble will displace all water between the bubble and the srnooth surface such that surface tension of the bubble will hold thé bubble to the panel and prevent it from rising upward.
To ensure "wetting" of ~he panel 30, the bottom surface is finished by sanding with an 80 grit sal~ paper in a s~irl pattern or fine .~andblasting with 220-240 grit sand at 100 psi. The res~ltant surface is simil~r to frosted glass. If the surface is too rough, however, bubble movernent can also be inpeded.
Akove each groove 34 near the upper end 38 of the acrylic panel 30 is a photocell 40. Photocells 40 are placed in small holes in the upper surface of the acrylic panel 30. A photocell retaining plate 42 above photocells 40 holds the photocells in position and is secured to the plexiglas panel by screws 44.` A photocell cover 46 is attached to the upper surface of the retaining plate 42. Photocell cover 46 is a plexiglas tubing through which extends the lead wires 48 and 50 to the photocells 40. The lead wires are encapsulated in a RTV rubber or a like compound which fills the interior of the photocell cover 46.
Extending below the acrylic panel 30 directly below the pho~ocells 40, is a sheet metal light bulb bracket 52. Bracket 52 is attached b~ the sides of the panel 30 by screws 53. Positioned directly below each photocell is a light bulb 54 in a ~ocket secured to the bracket 52. L~ght bulbs 54 can be incandescent lights or light emitting diodes, These lights 54 are used to provide light which is directed into ~ . . . ..
1325~62 the photocells 40 for aiding in detection of bubbles by the ~hotocells.
Extending belcw the bracket 52 is a wire conduit 56 made of E~lexiglas tubing. Lead wire 58 for the lights 54 is carried through the conduit 56 which is also filled with a RTV cvnlpound encapsulating the wire 58 within the conduit 56.
The electrical connections to the lights 54 and and photocells 40 are all water tight. The photocells are hermetically sealed in glass.
m e lead wires 48, S0 and 58 are all connected to a water ti~ht electrical connector 60. Connector 60 is in turn connected to the control circuit for the leak detection apparatus.
A side view of the upper end of the panel 30 is shown in Figure 3.
A bubble of air leaking from the component 20 will rise in the water until it contacts the bottom side of the panel 30. Once the bubb]e contacts the panel 30, it will rise along a surface 36 until it reaches a groove 34. Once in groove 34, the bubble will continue to rise throu~h the groove until it reaches the upper end 38 of the panel 30, from there the bubble wnll rise to the surface of the water. As the bubble rises through the groove 34, it will pass between a photocell 40 and light 54, interrupting the light directe~ toward the photocell ~uch that the bubble will be detected by the photocell 40.
A schematic of the electric circuit ~or operation of the photocells provided in Figure 4. The electrical signal produced by a photocell is first amplified by amplifier 70. The amplified signal then activates a n~nostable muti-vibrator 72 which produces a one half second timed pulse in response to a bubble detected by photocell 40. The ti~ed pulse from the muti-vibrator 72, which can be programmed for periods :;
~ 32~2 other than a half second, activates a decade counter 74. When the nu~ber of pulses counted by the decade counter exceeds a predetermined value, An alarm relay will be activated thereby indicating a le.~k in the component being tested. An amplifier and multi-vibrator ~re provided for each photocell 40 with the pulse generated by each of the nulti-vibrators being fed to a single decade counter for counting ~he total number of ~ubbles detected~
Depending on the sophistication required for the leak testir,g, a computer can be used in place of the decade coun~r for counting the number of bubbles. One advantage of using a computer is the capability of discriminating between random air bubbles which may have formed on the outside of the component as ~le component was being submerged, referred to as attached bubbles, and bub~es indicating a leak. For example, assume that it has heen determined that five bu~bles rising fro~ a component indica~e a leak. The decade counter will ~aicate a leak once five bubbles have been counted. ~wever~ ~he deca~ counter is not be able to discriminate between attached bubbles and le~ bubbles.
Attached bubbles will rise from ~and~m l~cations on the component surace. Leak bubbles wn the other han~. are formed at the same location on the component surface. The bubbles from a leak will he detected by a single photocell 40 or by two or three adjacent photocells.
5mall currents in the water may cause bubbles oriyi~ating f~c~l the same leak to be sensed by different photocells.
With a computer instead of t~ decade counterf each photocell can be m~nitored bo determine the number of bubbles detected by each pbotocell rather than ~erely sum the total number of bubbles detected by all photocell~ wi~h the decade counter.
' . ! ' ,.
~32~4~2 ~
~ he computer can be programn~l to add the bubbles detected from a set of two or more photocells positioned a~Dve adjacent grooves 34 in the panel 30. When the total bubble count for a set exceeds a predetermined number, for ~xample 5, this would indicate a leak and an alarm would be activated, rejecting the component being tested.
An example is shown in Table I of how these sets can be arranged and a possible scenario for the bubbles counted in each set. ln this example, one panel 30, having ten grooves 34 and photocells 40 is used to test the component. Eight sets of three adjacent p}lotocells are formed.
Set one is compxised of cells 1, 2, and 3. Set t1Y~ is comprised of ~ells 2, 3, and 4, etc. The sets are overlapping in that, except for the cells at the edge of the panel, each cell is in three different sets.
TABLE I
SET PHOqCX~LS BUBBLE COUNT
1 1, 2, 3 2 2, 3, 4 3 3 3- 4- 5 S Reject 4 4, 5, 6 4 5, 6, 7 3 6 6, 7, 8 7 7, 8, 9 8 8, 9, 10 ~ 1 ,: ~
~ 32~4~2 In khis example, the nu~ber of bubbles counted ~y the photocells in set three has reached the predetermined number of five, whereby a leak is indicated and the fault signal is activated. In this n~nner, the apparatus can discriminate between ive bubbles originating from random sources on the component surface and five bubbles khat are originating from approximately the same location. It is necessaxy to combine the bubbles counted in each adiacent grooves as currents in the water tank may cause bubbles originating from the same location to be direct~d to adjacent grooves as opposed to the same groove.
The computer can also be used to record the location of leaks in several components tested over a period of time which can be used to determine deficiencies in the manufacturing process of the component.
Data regarding the nu~ber of parts tested, accept-reject percentages, frequency of leakage by location and other data can also be generated by the computer.
An alternative electrical circuit is shown in Figure 5 which utilizes multiple decade counters instead of a computer ko discriminake bekween attached bubbles and leak bubbles. In Figure 5, sets are formed by two adjacent photocells as opposed to three as discussed above. The outputs of each of the monostable multi-vibrators 72 are fed to two decade counters. For example, the output from multi-vibrakor 72b is fed to counters 101 and 102, the output from multi-vibrator 72C is fed to counters 102 and 103, etc.
In this manner, the bubbles sensed by photocells 40b and 40c are counted by counter 102, the bubbles sensed by photocells 40c and 40d are cou~lted by counter 103, etc. Diodes 111-114 are used to pre~ent n~re than two adjacent counters from counting a single bubble. Although the -''~ ' . ;~'.
132a4~2 number of photocells in each set in this example is two, the sets can be formed by more than tWG photocells by addin~ more leads from the n~lti-vibrators to additional counters.
Discrimination between attachecl bubbles and leak bubbles is thus accamplished without the requirement of a computer. The circuit of Figure 5, unlike the computer, does not provide for data collection as previously described.
In operation, the component is tested by first sealing the openings, for example sealing the fuel filler pipe opening and the fuel sender opening in the tank 20 and then pressurizing the component. The component is retained in a fixture which is then submerged in the water in the tank 12. The bracket 28 with the panel 30 is supported in the water by the fixture above the tank 20.
Afte~ lowerlng the fixture in the water, a time delay of approximately eight ~econds is allc~ed to elapse before beginning the test. The delay i5 to allow attached bubbles which were for~d as the fixture was submerged to rise to the water surface. During this eight secor~ delay, the ccmputer can preform a system self check to determine i$ each photocell 40 is functioning. To preform this self check, the lights 54 are turned off and then on to ~enerate a pulse from each photocell. If one or more of the photocells are not functioning properly, an appropriate indicator will be activated and the testing operation stopped. After performir~ the self check and waiting for the eight second delay, the leak test is initiated and the space below each photocell 40 is searched for the presence of bubbles.
The length of the test depends upon the required sensitivity of the leak test. The smaller the allowable, the longer the test m~st be ' ~, ~ . . .
~32~2 conducted. The smaller the leak, the longer the tin~ necessary for enough gas to leak from the component to form a bub~le large enough to overconR the surface tension holding the bubble to the com~onent surface and allow it to rise to the water surface. Once the test has been completed, the fixture lB is removed from the tank 12 allowing access to the component for removal and transf~r to the appropriate location for either an accepted or rejected component.
The rate of bubble emission from a leak can be greatly increased by creating a partial vacuum in the tank above the water surface. m is will reduce the time reguired ~o preform the test. Figure 6 illustrates a tank equipped for use with a vacuum.
A tank cover plate 90 is attached to the upper cross member 23 by bolts 88. A seal 92 is mounted to the lower surface of plate 90 at its periphery. Seal 92 seals against the top surface of tank 12 when the fixture lB is completely lowered into the tank 12. Once sealed, a partial vacuum of approximately 15 inches hg is created in the tank by ~the vacuum pump 94 connected to the tank interior through conduit 96.
The test is then performed as described above. The vacuum results in an increased rate of bubble formation t~ereby reducing the time necessary for detecting a give leakage rate.
By automating the bubble detection in a liquid im~ersion leak test apparat~s, the primary disadvantage to liquid immersion testing, operator subjectivity is eliminated. The a~vantages however, such as lo cost, dura~ility and adaptability to m~re than one component are still retained with the automated leak detection.
It is to be understood that ~he invention is not limited to ~he exact construction or method illustrated and described above, but that .
' :` ' ' ' ' ~ ~325~62 various changes and ,~odifications may be n~de without departing from ~e spirit a.~d scope of the invention as defined in the following claims.
.
:, ' ,' ~
A ~UID CONl'AINING CHA~ER
I~ACKG~UND 0~ E INV~TICN
This invention relates to a leak detection apparatus and more particularly to an automated means for detecting leaks via liquid imnersion testing.
Numerous cor,~onents are rnanufactured which must neet a standard for a "leak tightness". Leak tightness is a relative term, as nothing can ever by completely free of leakage. A balance ~mst be made between the increasing cost of finc7ing smaller and smaller leaks and their importance to the functioning of the unit over its useful life. Leak tlghtness is the practical lealcage that is acceptable under norrnal operating circumstances.
Components which require some degree of leak tightness, for example, include fuel ~nks, radiators, fuel system components, water pumps, refrigeration components, heater cores, torque convertors, hydraulic and pnewnatic components etc. me acceptable leakage w~ll depend upon the usage of the co~fponent with respect to the type of fluid which rnust be contained, i.e. a gas or a liquid, and whether or not the contents will be pressurized.
Several leak detection methods are comnonly used in industry.
Eac~h rnethod has its awn advantages, limitations and sensitivity range.
As a result, not all rnethods are useful for every application. me correct choice of the leak detection ll~thod should optimize co~t, sensitivity and reliability of the test.
Liquid imnersion testing is one of the oldest doc~nented methods used to detect leaks. Liquid i~ersion testing operates on the basis of ' :
~,, ~, ' .
', ' ' ' " ~
~3254~2 a differential pressure at the leak creating a ~low of a gas from within the component to the liquid outside. The part being teste~ is pressurized with a gas and then immersed in a liquid medium, generally water. The gas escaping the pressurized component produces one or n,ore bubbles in the liquid which then rise to the surface of the water. m e com~onent being tested is allowed to ren~in in the liquid for a period of time while the lia,uid test nedium is examined for the presence of bubbles. The location of bubbles indicates the location of a leak and the frequency and size of the bubbles can be used to estimate the leakage rate.
Liquid immersion testing has several advantages which include, low equipment cost relative to other methods, location of the leak can be determined, the ea,uipment can easily be made durable enough for factory floor applications, and various size and shape components can be tested utilizing one test apparatus.
The prin~ry disadvantage with liqvid in~ersion testing is the require~ent of an operator to visually inspect the water for bubbles of leaking gas. This adds subjectivity to the test and, in addition, research has shown that an operatorls ability to accurately identify leaks decreases during the course of a typical eight hour work shift.
Accordingly, it is an object of this invention to provide a liquid in ~ rsion leak testing apparatus which includes an automatic neans for detecting the presen oe of bubkles of gas leaking from the component being tested.
~ t is an advantage of this invention that a low cost liquid immersion testing apparatus can be equipped with an automatic sensing .
.
, 1325~62 means which provides increased accuracy in detecting leaks without significantly increasing the cost of the device.
SUMMA~Y OF THE INVENTICN
~ he leak detection apparatus of this invention employs a tank for submerging the comp3nent to be tested in a liquid test medium, typically water. Other liquids may be used as long as they are compatible with the test apparatus and the component ~eing tested. Automatic identification of bubbles is accomplished by using a photoelectric detector such as the Clairex Cl-703L photocell. To provide complete coverage of the surface area above the component being tested, a plastic channeling device is used to direct the bukbles rising in the liquid along a predetermined path which passes beneath the photocell.
It is contemplated that the channeling device be constructed of a transparent plastic material such as acrylic which on its lower side has a plurality of ridges and grooves extending longitud m ally of the acrvlic panel. The panel is positioned in the liquid above the canponent being tested and is inclined along its length such that bubbles rising from the component wnll impact the acrylic panel, move upward to one of the grooves in the underside of the panel and travel along the gro~ve to the upwardly inclined end of the acrylic panel. A photocell is positioned above each groove at the upper end of the panel.
The number of photocèlls used can range fro~ two or thr~e to as many as lifty to provide coverage to the entire component being tested.
By increasing the number o~ photocells, the corresponding area of the co~ponent being tested by each detector is reduced, thereby increasing the accuracy of leak localization.
132~2 An electrical circuit, which may or may not include a computer, can be us~d to count the number of bu~bles detected by the photocells and a fault signal can be activated when the number of bubbles counted exeeds a predetermined number, thereby indicating a leaking component.
m e system can detect gxoss leaks to very small leaks having a leakage rate of 10 4 cc/sec. The test time must be increased as ~ensitivity is i~creased bo allow a bubble to be formed which is large enough ~o overcome the surface tension holding the bubble to the component surfa oe .
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.
ERlEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevation view of a immersion leak test apparatus employiny photoc~lls to automatically detect t e presence of bubb~es according to this inventivn;
Figure 2 is an end view as seen in the direction of arrow 2 of the channeling devioe used to direct the bubbles past the photocells;
Figure 3 is an enlarged side view of th2 upper end of the channeling devioe ;
Figure 4 is a schematic of the electric~l circuit used to count the bubbles and activate the fault signal;
Figure 5 is a schematic of a alternat~ve circuit to count bubbles which discriminates between attached bubbles formed when the component is submerged and leak bubbles; and ~32~2 Figure 6 is a side elevation view of a portion of the apparatus of Fisure 1 in which the tank is sealed and a partial vacuum is created in the tank abcve the water.
L~-lAILED DESCRIPTION OF THE INVENTION
_.
With reference t3 the drawings, an automated liquid immersion leaking apparatus 1~ is illustrated in Figure 1. The leak test apparatus includes a liquid holding ta~k 12 which oontains a quantity of water to a level indicated at 16.
Positioned above the water holding tank 12 is a cage like test fixture 18 which is used for lowering and raising a component 20, in this case a fuel tank, into and out of the water in the holding tank 12. The fixture 18 includes a base support member 21 upon which the fuel tank is positioned, vertic~l frame members 22 auld an upper cross member 23.
Extending upward from the cross member 23 is a support cylinder 24 which is used for raising and lowering the fixture 18 into and out of the water.
Positioned below the upper cross member 23 is an intermediate cross member 25 which supports a cylinder 26 for sealing the fuel sender opening in the top surface of the fuel tank. Another cylinder (not ~hown) is used for sealing the uel filler neck opening of the fuel t~nk.
In addition~ one or more other cylinders may be required for holding the fuel tank down against the base me~ber 21 while conducting the test.
Cylinder 26, In addition bo sealing the fuel sender opening, also includes a conduit for providing air pressure to the interior of the f~el tank once it is sub~erged in the water. The component 20 can be either .
: '.: , : ' , .. ..
. , , ;;
` 1325~2 -nanually or automatically positioned on the base 21 when the fixture 18 is in the raised position as shown in Figure 1.
A~so extending downward from the interme~iate cross member 25 are support brackets 28 which support acrylic panels 30 inclined relative to horizontal. Panels 30 are used to deflect any bubbles of air rising from the fuel tank past one of a plurallty of photocells positioned at the upper end of the acrylic panels 30 as will be discuss~d m detail below.
The panels 30 are shown in a position in which only a portion of the welded seam of ths fuel tank is being testsd for leaks. Additional panels 30 and photo oe lls can be positioned over other areas of the fuel tank 20 to provide leak testing of additional portions of the fuel tank.
Figure 2 is a view in the direction of arrow 2 of Figure 1 and illustrates the detail of the upper end 38 of the panels 30. The bottom surfa oe of the acrylic panel 30 is corrugated to form a plurality of evenly spaced ridges 32 and grooves 34 hav m g flat inclined surfaoes 36 extending between each ridge and groove. The ridges are spaced approximately two inches from each other. At the grooves 34, the surfaces 36 do not form a sharp corner but form a curved transition having a radius of approximately 1/4 inch The angle between adjacent surfaces 36 is approximately 135. The angle of inclination of the panel 30 in the water is approximately 20-30~ The angle of the panel 30 must be large enough to allow the bubbles to continuing rising in the grooves 34 However, as this angle is increased, the depth of the tank 12 must also be increased tD enable complete submerging of the panel 30 in the tank.
The bottom surface of the panel 30 must have a proper surface finish to prevent bubbles from sticking to the panel. ~he surface must : `
, .
,, .,, .. ~, .. :. . . ... .
~32~4~2 permit "wetting" or the formation of a film of water when the panel is out o~ the water. A surface that will not "wet" will forrn droplets of water on its surface as opposed to a water film. A smooth acrylic panel will not "wet". Wh~l an air bubble contacts a smooth panel, the bubble will displace all water between the bubble and the srnooth surface such that surface tension of the bubble will hold thé bubble to the panel and prevent it from rising upward.
To ensure "wetting" of ~he panel 30, the bottom surface is finished by sanding with an 80 grit sal~ paper in a s~irl pattern or fine .~andblasting with 220-240 grit sand at 100 psi. The res~ltant surface is simil~r to frosted glass. If the surface is too rough, however, bubble movernent can also be inpeded.
Akove each groove 34 near the upper end 38 of the acrylic panel 30 is a photocell 40. Photocells 40 are placed in small holes in the upper surface of the acrylic panel 30. A photocell retaining plate 42 above photocells 40 holds the photocells in position and is secured to the plexiglas panel by screws 44.` A photocell cover 46 is attached to the upper surface of the retaining plate 42. Photocell cover 46 is a plexiglas tubing through which extends the lead wires 48 and 50 to the photocells 40. The lead wires are encapsulated in a RTV rubber or a like compound which fills the interior of the photocell cover 46.
Extending below the acrylic panel 30 directly below the pho~ocells 40, is a sheet metal light bulb bracket 52. Bracket 52 is attached b~ the sides of the panel 30 by screws 53. Positioned directly below each photocell is a light bulb 54 in a ~ocket secured to the bracket 52. L~ght bulbs 54 can be incandescent lights or light emitting diodes, These lights 54 are used to provide light which is directed into ~ . . . ..
1325~62 the photocells 40 for aiding in detection of bubbles by the ~hotocells.
Extending belcw the bracket 52 is a wire conduit 56 made of E~lexiglas tubing. Lead wire 58 for the lights 54 is carried through the conduit 56 which is also filled with a RTV cvnlpound encapsulating the wire 58 within the conduit 56.
The electrical connections to the lights 54 and and photocells 40 are all water tight. The photocells are hermetically sealed in glass.
m e lead wires 48, S0 and 58 are all connected to a water ti~ht electrical connector 60. Connector 60 is in turn connected to the control circuit for the leak detection apparatus.
A side view of the upper end of the panel 30 is shown in Figure 3.
A bubble of air leaking from the component 20 will rise in the water until it contacts the bottom side of the panel 30. Once the bubb]e contacts the panel 30, it will rise along a surface 36 until it reaches a groove 34. Once in groove 34, the bubble will continue to rise throu~h the groove until it reaches the upper end 38 of the panel 30, from there the bubble wnll rise to the surface of the water. As the bubble rises through the groove 34, it will pass between a photocell 40 and light 54, interrupting the light directe~ toward the photocell ~uch that the bubble will be detected by the photocell 40.
A schematic of the electric circuit ~or operation of the photocells provided in Figure 4. The electrical signal produced by a photocell is first amplified by amplifier 70. The amplified signal then activates a n~nostable muti-vibrator 72 which produces a one half second timed pulse in response to a bubble detected by photocell 40. The ti~ed pulse from the muti-vibrator 72, which can be programmed for periods :;
~ 32~2 other than a half second, activates a decade counter 74. When the nu~ber of pulses counted by the decade counter exceeds a predetermined value, An alarm relay will be activated thereby indicating a le.~k in the component being tested. An amplifier and multi-vibrator ~re provided for each photocell 40 with the pulse generated by each of the nulti-vibrators being fed to a single decade counter for counting ~he total number of ~ubbles detected~
Depending on the sophistication required for the leak testir,g, a computer can be used in place of the decade coun~r for counting the number of bubbles. One advantage of using a computer is the capability of discriminating between random air bubbles which may have formed on the outside of the component as ~le component was being submerged, referred to as attached bubbles, and bub~es indicating a leak. For example, assume that it has heen determined that five bu~bles rising fro~ a component indica~e a leak. The decade counter will ~aicate a leak once five bubbles have been counted. ~wever~ ~he deca~ counter is not be able to discriminate between attached bubbles and le~ bubbles.
Attached bubbles will rise from ~and~m l~cations on the component surace. Leak bubbles wn the other han~. are formed at the same location on the component surface. The bubbles from a leak will he detected by a single photocell 40 or by two or three adjacent photocells.
5mall currents in the water may cause bubbles oriyi~ating f~c~l the same leak to be sensed by different photocells.
With a computer instead of t~ decade counterf each photocell can be m~nitored bo determine the number of bubbles detected by each pbotocell rather than ~erely sum the total number of bubbles detected by all photocell~ wi~h the decade counter.
' . ! ' ,.
~32~4~2 ~
~ he computer can be programn~l to add the bubbles detected from a set of two or more photocells positioned a~Dve adjacent grooves 34 in the panel 30. When the total bubble count for a set exceeds a predetermined number, for ~xample 5, this would indicate a leak and an alarm would be activated, rejecting the component being tested.
An example is shown in Table I of how these sets can be arranged and a possible scenario for the bubbles counted in each set. ln this example, one panel 30, having ten grooves 34 and photocells 40 is used to test the component. Eight sets of three adjacent p}lotocells are formed.
Set one is compxised of cells 1, 2, and 3. Set t1Y~ is comprised of ~ells 2, 3, and 4, etc. The sets are overlapping in that, except for the cells at the edge of the panel, each cell is in three different sets.
TABLE I
SET PHOqCX~LS BUBBLE COUNT
1 1, 2, 3 2 2, 3, 4 3 3 3- 4- 5 S Reject 4 4, 5, 6 4 5, 6, 7 3 6 6, 7, 8 7 7, 8, 9 8 8, 9, 10 ~ 1 ,: ~
~ 32~4~2 In khis example, the nu~ber of bubbles counted ~y the photocells in set three has reached the predetermined number of five, whereby a leak is indicated and the fault signal is activated. In this n~nner, the apparatus can discriminate between ive bubbles originating from random sources on the component surface and five bubbles khat are originating from approximately the same location. It is necessaxy to combine the bubbles counted in each adiacent grooves as currents in the water tank may cause bubbles originating from the same location to be direct~d to adjacent grooves as opposed to the same groove.
The computer can also be used to record the location of leaks in several components tested over a period of time which can be used to determine deficiencies in the manufacturing process of the component.
Data regarding the nu~ber of parts tested, accept-reject percentages, frequency of leakage by location and other data can also be generated by the computer.
An alternative electrical circuit is shown in Figure 5 which utilizes multiple decade counters instead of a computer ko discriminake bekween attached bubbles and leak bubbles. In Figure 5, sets are formed by two adjacent photocells as opposed to three as discussed above. The outputs of each of the monostable multi-vibrators 72 are fed to two decade counters. For example, the output from multi-vibrakor 72b is fed to counters 101 and 102, the output from multi-vibrator 72C is fed to counters 102 and 103, etc.
In this manner, the bubbles sensed by photocells 40b and 40c are counted by counter 102, the bubbles sensed by photocells 40c and 40d are cou~lted by counter 103, etc. Diodes 111-114 are used to pre~ent n~re than two adjacent counters from counting a single bubble. Although the -''~ ' . ;~'.
132a4~2 number of photocells in each set in this example is two, the sets can be formed by more than tWG photocells by addin~ more leads from the n~lti-vibrators to additional counters.
Discrimination between attachecl bubbles and leak bubbles is thus accamplished without the requirement of a computer. The circuit of Figure 5, unlike the computer, does not provide for data collection as previously described.
In operation, the component is tested by first sealing the openings, for example sealing the fuel filler pipe opening and the fuel sender opening in the tank 20 and then pressurizing the component. The component is retained in a fixture which is then submerged in the water in the tank 12. The bracket 28 with the panel 30 is supported in the water by the fixture above the tank 20.
Afte~ lowerlng the fixture in the water, a time delay of approximately eight ~econds is allc~ed to elapse before beginning the test. The delay i5 to allow attached bubbles which were for~d as the fixture was submerged to rise to the water surface. During this eight secor~ delay, the ccmputer can preform a system self check to determine i$ each photocell 40 is functioning. To preform this self check, the lights 54 are turned off and then on to ~enerate a pulse from each photocell. If one or more of the photocells are not functioning properly, an appropriate indicator will be activated and the testing operation stopped. After performir~ the self check and waiting for the eight second delay, the leak test is initiated and the space below each photocell 40 is searched for the presence of bubbles.
The length of the test depends upon the required sensitivity of the leak test. The smaller the allowable, the longer the test m~st be ' ~, ~ . . .
~32~2 conducted. The smaller the leak, the longer the tin~ necessary for enough gas to leak from the component to form a bub~le large enough to overconR the surface tension holding the bubble to the com~onent surface and allow it to rise to the water surface. Once the test has been completed, the fixture lB is removed from the tank 12 allowing access to the component for removal and transf~r to the appropriate location for either an accepted or rejected component.
The rate of bubble emission from a leak can be greatly increased by creating a partial vacuum in the tank above the water surface. m is will reduce the time reguired ~o preform the test. Figure 6 illustrates a tank equipped for use with a vacuum.
A tank cover plate 90 is attached to the upper cross member 23 by bolts 88. A seal 92 is mounted to the lower surface of plate 90 at its periphery. Seal 92 seals against the top surface of tank 12 when the fixture lB is completely lowered into the tank 12. Once sealed, a partial vacuum of approximately 15 inches hg is created in the tank by ~the vacuum pump 94 connected to the tank interior through conduit 96.
The test is then performed as described above. The vacuum results in an increased rate of bubble formation t~ereby reducing the time necessary for detecting a give leakage rate.
By automating the bubble detection in a liquid im~ersion leak test apparat~s, the primary disadvantage to liquid immersion testing, operator subjectivity is eliminated. The a~vantages however, such as lo cost, dura~ility and adaptability to m~re than one component are still retained with the automated leak detection.
It is to be understood that ~he invention is not limited to ~he exact construction or method illustrated and described above, but that .
' :` ' ' ' ' ~ ~325~62 various changes and ,~odifications may be n~de without departing from ~e spirit a.~d scope of the invention as defined in the following claims.
.
:, ' ,' ~
Claims (31)
1. An apparatus for leak testing at least a portion of a fluid containing chamber by detecting bubbles of a gas rising from said portion when pressurized and submerged in a liquid comprising:
means positionable in said liquid above said chamber for deflecting said bubbles past one of a plurality of predetermined locations;
photoelectric means adjacent said predetermined locations for detecting said bubbles passing said predetermined locations and producing an electrical signal in response thereto; and means for counting the number of electrical signals.
means positionable in said liquid above said chamber for deflecting said bubbles past one of a plurality of predetermined locations;
photoelectric means adjacent said predetermined locations for detecting said bubbles passing said predetermined locations and producing an electrical signal in response thereto; and means for counting the number of electrical signals.
2. The apparatus of claim 1 wherein:
said photoelectric means comprises a photocell in optical communication with each of said predetermined locations.
said photoelectric means comprises a photocell in optical communication with each of said predetermined locations.
3. The apparatus of claim 2 further comprising:
means for adding the number of electrical signals produced by two or more photocells in communication with adjacent predetermined locations.
means for adding the number of electrical signals produced by two or more photocells in communication with adjacent predetermined locations.
4. The apparatus of claim 3 further comprising:
means for indicating a leak from said chamber when the sum of said electrical signals from said two or more photocells exceeds a predetermined number.
means for indicating a leak from said chamber when the sum of said electrical signals from said two or more photocells exceeds a predetermined number.
5. The apparatus of claim 1 further comprising a light radiation source adjacent each of said plurality of predetermined locations opposite and photoelectric detection means, a portion of said light radiation directed toward said photoelectric detection means.
6. The apparatus of claim 2 wherein:
said deflecting means includes a panel of a transparent material having a corrugated surface of alternating parallel ridges and grooves extending in one direction along the bottom surface of said panel;
said panel is inclined upwardly in said one direction whereby said rising bubbles travel through said grooves past the upward end of said panel; and said predetermined location being in each of said grooves near said upwardly inclined end of said panel.
said deflecting means includes a panel of a transparent material having a corrugated surface of alternating parallel ridges and grooves extending in one direction along the bottom surface of said panel;
said panel is inclined upwardly in said one direction whereby said rising bubbles travel through said grooves past the upward end of said panel; and said predetermined location being in each of said grooves near said upwardly inclined end of said panel.
7. The apparatus of claim 6 wherein said transparent material is a polymeric material.
8. The apparatus of claim 6 wherein said photocells are mounted to the upper surface of said panel above each groove near said upwardly inclined end.
9. The apparatus of claim 6 wherein the bottom surface of said panel is textured to provide for the formation of a film of water on said surface when wetted.
10. An apparatus for detecting leaks in at least a portion of a fluid containing chamber, said portion being pressurized with a gas and submerged in a liquid, comprising:
means for submerging said portion in said liquid whereby gas leaking from said portion will form bubbles rising from said portion to the surface of said liquid;
means positionable in said liquid above said portion for deflecting said rising bubbles past one of a plurality of predetermined locations;
photoelectric detection means adjacent each of said predetermined locations for detecting said bubbles passing said predetermined locations;
means for counting the number of bubbles detected by said photoelectric means; and means for indicating a leaking chamber when said number of bubbles exceeds a predetermined number.
means for submerging said portion in said liquid whereby gas leaking from said portion will form bubbles rising from said portion to the surface of said liquid;
means positionable in said liquid above said portion for deflecting said rising bubbles past one of a plurality of predetermined locations;
photoelectric detection means adjacent each of said predetermined locations for detecting said bubbles passing said predetermined locations;
means for counting the number of bubbles detected by said photoelectric means; and means for indicating a leaking chamber when said number of bubbles exceeds a predetermined number.
11. The apparatus of claim 10 wherein:
said photoelectric means comprises a photocell adjacent said predetermined locations.
said photoelectric means comprises a photocell adjacent said predetermined locations.
12. The apparatus of claim 11 further comprising a light radiation source adjacent said predetermined locations opposite said photocells, a portion of said light radiation directed toward said photocells.
13. The apparatus of claim 10 wherein said deflecting means includes a transparent material.
14. The apparatus of claim 13 wherein said transparent material is a polymeric material.
15. The apparatus of claim 11 further comprising:
means for adding the number of bubbles detected by two or more adjacent photocells; and means for indicating a leaking chamber when said number of bubbles detected by said two or more adjacent photocells exceeds a predetermined number.
means for adding the number of bubbles detected by two or more adjacent photocells; and means for indicating a leaking chamber when said number of bubbles detected by said two or more adjacent photocells exceeds a predetermined number.
16. The apparatus of claim 10 further comprising:
means for creating a partial vacuum in said tank above said liquid.
means for creating a partial vacuum in said tank above said liquid.
17. A method of leak testing a fluid containing chamber comprising the steps of:
pressurizing said chamber with a gas;
submerging said chamber in a liquid whereby said gas leaking from said chamber will form bubbles which rise to the surface of said liquid;
deflecting said bubbles past one of a plurality of predetermined locations;
deflecting the presence of said bubbles as said bubbles pass said predetermined locations;
counting the number of bubbles passing said predetermined locations; and indicating a leaking chamber when the number of bubbles exceeds a predetermined number.
pressurizing said chamber with a gas;
submerging said chamber in a liquid whereby said gas leaking from said chamber will form bubbles which rise to the surface of said liquid;
deflecting said bubbles past one of a plurality of predetermined locations;
deflecting the presence of said bubbles as said bubbles pass said predetermined locations;
counting the number of bubbles passing said predetermined locations; and indicating a leaking chamber when the number of bubbles exceeds a predetermined number.
18. The method of claim 17 wherein:
said bubbles are detected by a photocell at each of said plurality of predetermined locations.
said bubbles are detected by a photocell at each of said plurality of predetermined locations.
19. The method of claim 18 further comprising:
summing the number of bubbles detected by a plurality of adjacent photocells; and indicating a leak from said chamber when said sum exceeds a predetermined number.
summing the number of bubbles detected by a plurality of adjacent photocells; and indicating a leak from said chamber when said sum exceeds a predetermined number.
20. The method of claim 17 wherein said counting of said bubbles further comprises the steps of:
producing an electrical signal by said photocell when a bubble is detected;
producing a timed pulse of electrical current from a monostable multi-vibrator in response to said electrical signal;
counting the number of electrical pulses; and indicating a leak from said chamber when the number of electrical pulses exceeds a predetermined number.
producing an electrical signal by said photocell when a bubble is detected;
producing a timed pulse of electrical current from a monostable multi-vibrator in response to said electrical signal;
counting the number of electrical pulses; and indicating a leak from said chamber when the number of electrical pulses exceeds a predetermined number.
21. A method of leak testing a fluid containing chamber comprising the steps of:
pressurizing said chamber with a gas;
submerging said chamber in a liquid whereby said gas leaking from said chamber will form bubbles which rise to the surface of said liquid;
deflecting said bubbles past one of a plurality of predetermined locations;
detecting the presence of said bubbles with a photocell as said bubbles pass one of said predetermined locations;
counting the number of bubbles detected; and indicating a leaking chamber when the number of bubbles exceeds a predetermined number.
pressurizing said chamber with a gas;
submerging said chamber in a liquid whereby said gas leaking from said chamber will form bubbles which rise to the surface of said liquid;
deflecting said bubbles past one of a plurality of predetermined locations;
detecting the presence of said bubbles with a photocell as said bubbles pass one of said predetermined locations;
counting the number of bubbles detected; and indicating a leaking chamber when the number of bubbles exceeds a predetermined number.
22. The method of claim 21 further comprising the step of discriminating between attached bubbles formed on the outer surface of said chamber when said chamber is submerged and leak bubbles formed from gas leaking from said chamber after being submerged by summing the number of bubbles detected by at least two adjacent photocells and indicating a leak when said sum exceeds said predetermined number.
23. The method of claim 21 further comprising:
stimulating each photocell; and stopping the leak test if an output is not produced by each photocell.
stimulating each photocell; and stopping the leak test if an output is not produced by each photocell.
24. The method of claim 21 further comprising:
waiting a predetermined time after submerging said fluid containing chamber before detecting said bubbles to allow attached bubbles formed on the outer surface of said chamber when said chamber is submerged to rise to the said liquid surface.
waiting a predetermined time after submerging said fluid containing chamber before detecting said bubbles to allow attached bubbles formed on the outer surface of said chamber when said chamber is submerged to rise to the said liquid surface.
25. The method of claim 21 further comprising the step of:
creating a partial vacuum above said liquid.
creating a partial vacuum above said liquid.
26. An apparatus for detecting leaks in at least a portion of a fluid containing chamber, said portion being pressurized with a gas and submerged in a liquid, comprising:
means for submerging said chamber in said liquid whereby gas leaking from said chamber will form bubbles rising from said chamber to the surface of said liquid;
a panel of a transparent material positionable in said liquid above said portion of a fluid containing chamber having a corrugated surface of alternating parallel ridges and grooves extending in one direction along the bottom surface of said panel, said panel inclined upwardly in said one direction whereby said rising bubbles travel through said grooves past the upwardly inclined end of said panel;
a photocell above each groove adjacent said upwardly inclined end for detecting said bubbles travelling through said grooves and producing an electrical output signal;
means for counting the number of bubbles detected by said photocells means; and means for indicating a leaking chamber when said number of bubbles exceeds a predetermined number.
means for submerging said chamber in said liquid whereby gas leaking from said chamber will form bubbles rising from said chamber to the surface of said liquid;
a panel of a transparent material positionable in said liquid above said portion of a fluid containing chamber having a corrugated surface of alternating parallel ridges and grooves extending in one direction along the bottom surface of said panel, said panel inclined upwardly in said one direction whereby said rising bubbles travel through said grooves past the upwardly inclined end of said panel;
a photocell above each groove adjacent said upwardly inclined end for detecting said bubbles travelling through said grooves and producing an electrical output signal;
means for counting the number of bubbles detected by said photocells means; and means for indicating a leaking chamber when said number of bubbles exceeds a predetermined number.
27. The apparatus of claim 26 wherein said counting means comprises:
means for amplifying the output from said photocells;
monostable multi-vibrator means for producing a timed pulse in response to the output from said amplifying means;
and a counter for counting the number of pulses from said multi-vibrator means.
means for amplifying the output from said photocells;
monostable multi-vibrator means for producing a timed pulse in response to the output from said amplifying means;
and a counter for counting the number of pulses from said multi-vibrator means.
28. An apparatus for leak testing at least a portion of a fluid containing chamber by detecting bubbles of a gas rising from said portion when pressurized and submerged in a liquid comprising:
means for creating a partial vacuum above said liquid;
means positionable in said liquid above said portion of a fluid containing chamber for deflecting said bubbles past one of a plurality of predetermined locations;
photoelectric means adjacent said predetermined location for detecting said bubbles passing said predetermined locations and producing an electrical signal in response thereto; and means for counting the number of electrical signals.
means for creating a partial vacuum above said liquid;
means positionable in said liquid above said portion of a fluid containing chamber for deflecting said bubbles past one of a plurality of predetermined locations;
photoelectric means adjacent said predetermined location for detecting said bubbles passing said predetermined locations and producing an electrical signal in response thereto; and means for counting the number of electrical signals.
29. An apparatus for leak testing at least a portion of a fluid containing chamber by detecting bubbles of a gas rising from said portion when submerged in a liquid comprising:
an elongated panel oriented generally horizontally in said liquid above said chamber for deflecting said bubbles past at least one predetermined elongated section;
a light radiation source for projecting a beam of focused light along each said predetermined elongated section;
means disposed adjacent each said predetermined elongated section opposite said light radiation source for receiving said beam of light, each said receiving means producing a signal when said beam of light is interrupted by a bubble passing through said predetermined elongated section; and means for counting the number of said signals.
an elongated panel oriented generally horizontally in said liquid above said chamber for deflecting said bubbles past at least one predetermined elongated section;
a light radiation source for projecting a beam of focused light along each said predetermined elongated section;
means disposed adjacent each said predetermined elongated section opposite said light radiation source for receiving said beam of light, each said receiving means producing a signal when said beam of light is interrupted by a bubble passing through said predetermined elongated section; and means for counting the number of said signals.
30. The apparatus of claim 29 having a plurality of predetermined elongated sections and wherein said counting means is configured to determine which of said elongated sections a bubble has passed.
31. The apparatus of claim 30 wherein said counting means further comprising a timer and a logic circuit to statistically evaluate the number of signals from said receiving means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/234,805 US4854158A (en) | 1988-08-22 | 1988-08-22 | Method and apparatus for leak testing a fluid containing chamber |
| US234,805 | 1988-08-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1325462C true CA1325462C (en) | 1993-12-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000593212A Expired - Fee Related CA1325462C (en) | 1988-08-22 | 1989-03-09 | Method and apparatus for leak testing a fluid containing chamber |
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| US (1) | US4854158A (en) |
| EP (1) | EP0355942B1 (en) |
| JP (1) | JP2643440B2 (en) |
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| CA (1) | CA1325462C (en) |
| DE (1) | DE68911062D1 (en) |
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| CH493837A (en) | 1968-07-13 | 1970-07-15 | Sacofgas Spa | Photoelectric bubble counter for checking the gas tightness of containers and interception devices in general |
| CH494955A (en) * | 1969-03-05 | 1970-08-15 | Sacofgas Spa | Device for the immersion control of the gas tightness of containers, taps or valves |
| JPS4986081A (en) * | 1972-12-21 | 1974-08-17 | ||
| JPS5357083A (en) * | 1976-11-04 | 1978-05-24 | Sanshu Press Kogyo Kk | Bubble detector |
| JPS6029146Y2 (en) * | 1982-05-07 | 1985-09-04 | 三菱電機株式会社 | rotary switch |
| JPS6085349A (en) * | 1983-10-17 | 1985-05-14 | Tadaki Yokoe | Method and apparatus for checking leakage of drum |
| JPS61148338A (en) * | 1984-12-24 | 1986-07-07 | Hitachi Ltd | Inspector |
-
1988
- 1988-08-22 US US07/234,805 patent/US4854158A/en not_active Expired - Fee Related
-
1989
- 1989-03-09 CA CA000593212A patent/CA1325462C/en not_active Expired - Fee Related
- 1989-03-10 AU AU31233/89A patent/AU629817B2/en not_active Ceased
- 1989-03-22 DE DE89302850T patent/DE68911062D1/en not_active Expired - Lifetime
- 1989-03-22 EP EP89302850A patent/EP0355942B1/en not_active Expired - Lifetime
- 1989-04-20 KR KR1019890005212A patent/KR900003618A/en not_active Application Discontinuation
- 1989-05-10 JP JP1115268A patent/JP2643440B2/en not_active Expired - Lifetime
- 1989-06-13 BR BR898902807A patent/BR8902807A/en not_active Application Discontinuation
- 1989-06-21 MX MX016561A patent/MX165712B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR8902807A (en) | 1990-09-18 |
| US4854158A (en) | 1989-08-08 |
| EP0355942A3 (en) | 1990-08-16 |
| EP0355942A2 (en) | 1990-02-28 |
| JPH0255928A (en) | 1990-02-26 |
| KR900003618A (en) | 1990-03-26 |
| DE68911062D1 (en) | 1994-01-13 |
| JP2643440B2 (en) | 1997-08-20 |
| MX165712B (en) | 1992-12-01 |
| EP0355942B1 (en) | 1993-12-01 |
| AU3123389A (en) | 1990-02-22 |
| AU629817B2 (en) | 1992-10-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |