US 3921006 A
An apparatus for controlling the pressure differential applied to the particle study device for causing a suspension of particulate matter to pass through an aperture includes an isolated manometer tube. An inelastic flexible bag is secured to and covers one open end of the manometer tube. The bag is positioned in a chamber which is coupled to the particle study device. The manometer fluid is displaced into the bag causing it to expand and expel fluid in the chamber. When the manometer fluid is allowed to return to equilibrium in the manometer tube the exit of the fluid from the bag collapses the bag and causes a pressure differential in the chamber which is coupled to the particle study device for causing passage of the suspension through the aperture.
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Description (OCR text may contain errors)
United States Patent 1 11 1 1111 3,921,006 Pontigny 5] Nov. 18 1975 PARTICLE COUNTING APPARATUS INCLUDING ISOLATED MANOMETER Primary Examiner-Alfred E. Smith Assistant ExaminerRolf l-Iille  Inventor' 22322 Pontlgny Montmorency Attorney, Agent, or Firm-Silverman & Cass, Ltd.
 Assignee: Coulter Electronics, Inc., Hialeah,  ABSTRACT Fla. An apparatus for controlling the pressure differential  Flled: Sept 1974 applied to the particle study device for causing a sus- 2 AppL 506,298 pension of particulate matter to pass through an aperture includes an isolated manometer tube. An inelastic flexible bag is secured to and covers one open end of U-S- the manometer tube The bag is positioned in a cham- -H01H G ber which is coupled to the particle study device. The GOIL 7/ 18 manometer fluid is displaced into the bag causing it to  Field Of Search"; 324/71 CP, 73/401; expand and expel fluid in the chamber. When the ma- 307/118 nometer fluid is allowed to return to equilibrium in the manometer tube the exit of the fluid from the bag col- References Cited lapses the bag and causes a pressure differential in the UNITED STATES PATENTS chamber which is coupled to the particle study device 2,656,508 10/1953 324/71 CP for causing passage of the suspension through the ap- 3,2s9,s42 7/1966 324/71 CP enure- 3,453,438 7/1969 I 324/71 CP X 3,614,607 10/1971 324/71 CP 19 Chums l Draw'ng F'gure 3,838,601 10/1974 Dorman 324/71 CP TO SOURCE OF VACUUM '8 34 34 68 20 1 2 22 38 J 2 PARTICLE ANALYZER US. Patent Nov. 18, 1975 3,921,006
TO SOURCE OF VACUUM n \PARTICLE 4 ANALYZER J s4 I 7 /\T6 PARTICLE COUNTING APPARATUS INCLUDING ISOLATED .MANOMETER BACKGROUND or THE INVENTION The present invention relates to'fluid pressure monitoring devices of the manometer type and particularly to a manometer system used in association with a particle study device of the type presently classified in Class 324, Subclass 7l. 7 a Y In particle study devices of the type such as is disclosed in U.S. Pat. No. 2,656,508, a first, small vessel is partially immersed in a fluid contained in a second larger vessel. The fluid contains a suspension of particulate matter. The smaller vessel has an aperture formed in its wall below the fluid level. A source of vacuum is connected to the smaller vessel creating a pressure differential which causesthe fluid, and particulate matter to be drawn from the larger vessel through the aperture into the smaller vessel.ln the use of the particle study device, as each particle in thefluid suspension passes through the aperture it is sensed and analyzed by a technique now commonly referred to as the Coulter principle and first disclosed in the above noted US,
Pat. No. 2,656,508. This .type of particle study device is now commonly referred to as a Coulter type particle study device. I
In a Coulter type particle. study device it is desirable to draw the fluid suspension through the aperture at a constant rate and to meter the exact amount of fluid suspension passing through'the aperture in a predetermined time period. This is most often accomplished by use of a manometer-syphon arrangement such as is disclosed in US. Pat. No. 3,259,842. In this patent a generally U-shaped mercury manometer is attached to the small inner tube. When the source of vacuum noted above is connected to the inner tube it will cause the mercury in the U-shaped manometer todisplace and rise into the leg of the manometer'connected to the smaller inner vessel. When the vacuum is removed the mercury will attempt to return to an'equilibrium state in the U-shaped manometer tube. This will create a constant pressure differential within the inner vessel causing the fluid suspension to be drawn through the aperture and into the inner vessel;
The manometer tube described in the aforementioned US. Pat. No. 3,259,842 also includes a pair of contacts located in a section of the tube. These contacts are spaced apart by apredetermin'e'cl distance defining a predetermined volume of mercury,and are connected to the particle study device for starting and stopping the particle study device. By measuring the passage of a predetermined volume of mercury past the two points noted and knowing the aperture size and flow rate throughthe aperture in response to the fixed pressure differential, the volume of fluid suspension passing through the aperture can be ascertained.
In the above described apparatus the mercury in the U-shaped tube must be displaced to a'fixed height in one leg in order to maintain a predetermined pressure differential within the inner vessel. If the mercury is displaced to a lower level insufficient pressure will be maintained resulting in the passage of a'smaller-volume of fluid suspension. If it is displaced to a higher level excessive pressure will be' applied causing an excessive volume of fluid suspension to pass through the aperture. It also is possible for the excessive" pressure to u-removal of the fluid in the inner vessel. This contact often times will contaminate the mercury requiring replacement of the mercury and a complete cleaning of the manometer structure, a time consuming and expensive process.
SUMMARY OF THE INVENTION In practicing this invention an apparatus including an isolated manometer is provided which is particularly adapted for use in a particle study device wherein pressure differential causes a suspension of particulate matchamber. Means are provided for displacing the fluid in the manometer into the'bag defining the inner portion to expand the same, expel fluid from a portion of the chamber and create a disequilibrium in the manometer.
Upon removal of the displacing means the manometer fluid will exit the bag causing it to collapse and create a pressure differential in the chamber. This pressure differential is coupled to the particle study device for causing the suspension to. pass through the aperture.
BRIEF DESCRIPTION OF THE DRAWINGS The single FIGURE is a vertical section view taken through the apparatus of this invention connected to a particle study device, portions of the device and apparatus being shown diagrammatically.
DESCRIPTION, OF THE PREFERRED EMBODIMENT,
Referring to the drawing, a particle study device of the Coulter type is shown including an inner closed vessel 10 and an outer open vessel 12 which may be-a sim ple beaker. The inner vessel 10 is filledwith an electricallyconductive fluid 14 and is at least partially immersed in the body of a fluid suspension 16 carried in the outer vessel 12. The fluid suspension 16 includes particles whose concentration or properties it is desired to study. The lateral wall of the inner vessel 10 is provided with a fine aperture 18 which, in most instances, ranges from 20 to 200 microns in diameter. Aperture 18 is the principle or only electrical and physical path existing between the two vessels 10 and 12. An electrode 20 is positioned in outer vessel 12 and connected to a particle analyzer 22 of the Coulter type via conductor 24. A second electrode 26 is located in the inner vessel Y10 and is also coupled to particle analyzer 22 via a conductor 28.
According to the Coulter principle, a quantity of the fluid suspension in vessel 12 is drawn through aperture 18 into vessel 10 by applying a source of vacuum or pressu-redifferential to the interior of vessel 10. When particle analyzer 22 is operative it will permit current to flow. through conductors 24 and 28 electrodes 20 and 26 and fluid l4 and 16 establishing a current flow arid/or potential across aperture 18. Whenever a particle in fluid suspension 16 passes through aperture 18 the total impedance of the contents of the aperture will vary causing a modulation of the current flow and/or potential. This modulation of the current flow and/or electric field creates an electrical change which will be detected by particle analyzer 22 and can be used in order to count and size the particle passing through aperture 18.
The apparatus of this invention includes a tube 30 connected from the upper end of vessel to a control valve 32, which is coupled via tube 34 to a source of vacuum. Tube is also coupled to an aperture 43 in the top wall of a housing 36. Housing 36 defines a chamber 38 for receiving excess fluid drawn from vessel 10. Bottom wall 40 of housing 36 in the embodiment shown is a drain plug which may be removed for draining fluid from chamber 38.
A flexible inelastic bag 42 is positioned within chamber 38 forming an inner portion within chamber 38 and dividing chamber 38 into an inner and outer portion. In the preferred embodiment bag 42 is a plastic relatively impervious material, preferably polytetrafluoroethylene.
A generally vertically disposed U-shaped manometer identified generally by the numeral 44 includes a first leg 46 consisting of vertically disposed capillary tubing which extends through an aperture 48 formed in bottom wall 40 of housing 36 into chamber 38. Bag 42 is secured to the end of capillary tubing 46 in chamber 38 isolating that end from chamber 38. A horizontally disposed center or bight section 50 of capillary tubing connects first leg 46 to a second vertically disposed leg identified generally by the numeral 52. Leg 52 includes a reservoir 54 connected at its lower end to the end of bight portion 50 and at its upper end to a short section of capillary tubing 56. Capillary tubing 56 is connected at its upper end to a horizontally disposed section of leg 52 identified as volume measuring section 58. A pair of electrical contacts 60 and 62 are positioned in measuring section 58 and connected via conductors 64 and 66 to particle analyzer 22. Contact 60 is the start contact for particle analyzer 22 and contact 62 is the stop contact. Another vertically disposed section of capillary tubing 68 is connected to the end of section 58 adjacent to contact 62. A flexible inelastic bag is secured to and seals the upper open end of capillary tubing section 68. Bag 70 is preferably the same material as bag 42 and has an identical volumetric capacity.
Manometer 44 is partially filled with mercury 72 which is shown in an equilibrium state at maximum levels in both legs represented by the dashed line 76. When the mercury is in an equilibrium state in manometer 44 it will be slightly below the open end of leg 46 and above section 58 in leg 52. A gas, preferably nitrogen, fills the remaining portions of capillary tube section 68 in leg 52 and bag 70.
In order to operate the apparatus and initialize operation of the particle study device, valve 32 is opened connecting the source of vacuum to vessel 10 and chamber 38 via tubing 30. The vacuum will create a pressure differential which will cause a small amount of fluid suspension 16 to pass through aperture 18 into vessel 10 and will also cause fluid 14 in vessel 10 to be drawn through valve 32. The amount drawn from vessel 10 however will be small because of the'resistance created by the small aperture 18. The vacuum also will create a pressure differential within chamber 38 which will cause the mercury 72 inmanometer 44 to be drawn into and fill bag 42. As noted previously bag 42 is inelastic so that it will expand to full capacity from its col- 4 lapsed condition and accept a predetermined volume of mercury. As bag 42 expands the fluid in the outer portion of chamber38 will be forced out of chamber 38 through tubing 30 and valve 32 towards the source of vacuum. When bag 42 is filled the mercury level in leg 52 of manometer 44 will be at about the mid-point of reservoir 54, and bag will have collapsed. The collapse of bag 70 and the inelastic nature of bags 42 and 70 acts to prevent an excessive transfer of mercury into bag 42 and an over expansion of bag 42 in the presence of excessive vacuum and pressure in chamber 38 which can damage vessel 10 or aperture 30.
When the mercury 72 has filled bag 42, valve 32 is closed cutting off the source of vacuum. The mercury in manometer 44 and bag 42 is in a state of disequilibrium and will begin to exit bag 42 in order to return to an equilibrium state as shown by the dashed line 76. As the mercury exits bag 42 bag 42 will begin to collapse and create a pressure differential or vacuum in chamber 38 which is communicated via tubing 30 to vessel 10. This pressure differential will cause fluid suspension 16 to begin passing through aperture 18.
As the mercury level in leg 52 of manometer 44 rises it will pass contact 60. The conductive mercury will provide an electrical path through contact 60 for starting particle analyzer 22. When a predetermined volume of fluid suspension 16 has passed through aperture 18 and'has been measured by analyzer 22 the mercury will pass contact 62 in section 58 of leg 52 providing an electrical path through contact 62 which stops particle analyzer 22 completing the analysis cycle.
From the foregoing description, it will be readily apparent that apparatus including an isolated manometer for use with a particle study device provides a number of advantages, some of which have been described above and others which are inherent in the invention. It will also be obvious to those skilled in the art that modifications can be made to the apparatus without departing from the spirit and scope of the invention. Accordingly the scope of the invention is only to be limited in accordance with the accompanying claims.
What is claimed and desired to secure Letters Patent of the United States is:
1. An apparatus particularly adopted for use in a particle study device wherein pressure differential causes a suspension of particulate matter to pass through an aperture, said apparatus including in combination,
a housing defining a chamber and having an inner flexible inelastic portion, manometer means having a first open end coupled to said chamber inner portion,
means for displacing the manometer fluid from said manometer means into said chamber inner portion to expand same and create a disequilibrium in said manometer, said manometer fluid upon a removal of said displacing means exiting said portion, collapsing said portion and creating a pressure differential in said chamber, and
coupling means coupling said chamber to said device for coupling said pressure differential thereto.
2. The apparatus of claim 1 wherein said manometer means is a generally vertically disposed U-shaped manometer tube having a first leg including said first open end, a second leg and a bight portion therebetween, said manometer fluid being in equilibrium when filling said bight portion and at substantially the same height in said first and second legs.
3. The apparatus of claim 2 wherein said inner portion is a flexible inelastic bag.
4. The apparatus of claim 3 wherein said second leg has an open end and further including a flexible inelastic bag secured to said second leg and covering said open end thereof for limitingmovement of said fluid within said manometer and into said first leg.
5. The apparatus of claim 4 wherein said second bag is filled with nitrogen.
6. The apparatus of claim 1 wherein said-coupling means is a tube coupling said housing chamber to said device.
7. The apparatus of claim 1 wherein said means for displacing the manometer fluid is a source of vacuum, said coupling means including a second tube having a valve therein coupled to said first tube for coupling said source of vacuum to said chamber, said source of vacuum creating a pressure differential in said chamber for expanding said inner portion and displacing said manometer fluid.
8. The apparatus of claim 1 wherein said fluid is mercury.
9. A manometer apparatus particularly adapted for use in a particle study device wherein a pressure differential causes a suspension of particulate matter to pass through a microscopic aperture including in combination;
a housing defining a chamber,
coupling means coupling said chamber to said study device and to a source of vacuum,
a generally vertically disposed U-shaped manometer tube having a first leg, a second leg and a bight portion therebetween, said first leg having a first open end in communication with said chamber, I
a bag of flexible inelastic material secured to said first leg first open end to isolate said end from said chamber and for dividing said chamber into an inner and outer portion, I
said bight portion and portions of said first and second legs having a manometer fluid therein,
said fluid being responsive to application of .said
source of vacuum to displace into said bag and responsive to removal of said vacuum to withdraw 6 from said bag, said withdrawal creating said pressure differential for causing passage of said suspension through said aperture.
10. The apparatus of claim 9 wherein said manometer tube second leg has an open end and further including a second bag of flexible inelastic material secured to said second leg and covering said open end for limiting movement of said fluid within said manometer and bags.
11. The apparatus of claim 10 wherein a portion of said manometer tube second leg and said bag secured thereto is filled with nitrogen.
12. The apparatus of claim 10 wherein said first and second bags define equal volumes.
13. The apparatus of claim 9 wherein said second leg includes start means operative in response to passage of I said fluid past a first location thereon to start said study device, and stop means operative in response to passage of said fluid past a second location thereon to stop said study device.
14. The apparatus of cliam 13 wherein said fluid is an electrically conductive fluid and said start means include a pair of normally open contacts secured to said second leg at said first location and coupled to said particle study device, said conductive fluid completing an electrical path between said contacts for starting said particle study device.
15. The apparatus of claim 13 wherein said stop means include normally open contacts secured to said second leg at said second location and coupled to said particle study device, said conductive fluid completing an electrical path between said contacts for stopping said particle study device.
16. The apparatus of claim 13 wherein said fluid is mercury.
17. The apparatus of claim 9 wherein said bag is formed from a plastic material.
18. The apparatus of claim 17 wherein said plastic material is polytetrafluoroethylene.
19. The apparatus of claim 9 wherein said housing includes drain means for draining said chamber.