Displacement metering with independent ancillary flow

• US 4,001,678 A
• Filed: 06/16/1975
• Issued: 01/04/1977
• Est. Priority Date: 05/16/1974
• Status: Expired due to Term

• Current Assignee: Particle Data Incorporated
• Original Assignee: Robert H. Berg
• Inventors: Berg, Robert H.
• Primary Examiner(s): Segal, Robert
• Assistant Examiner(s): Sunderdick, Vincent J.
• Application Number:
  US05/587,287
• Time in Patent Office: 568 Days
• Field of Search: 324/71 CP, 137/205, 137/392, 137/240, 73/401, 318/306
• US Class Current: 324/71.1
• CPC Class Codes: G01N 15/12 by observing changes in resistance or impedance across apertures when traversed by individual particles, e.g. by using the Coulter principle
• CPC Class Codes: Y10T 137/3109 Liquid filling by evacuating container
• CPC Class Codes: Y10T 137/4259 With separate material addition

Abstract

Displacement metering with two independently metered fluid flows comprises displacing fluid in laminar filament flow from a first chamber through a second chamber into a third chamber, the chambers being separated by a pair of spaced walls provided with coaxially aligned orifices in communicating series relationship. Flow in filamentary form is effected from the first chamber through the orifices seriatim into the third chamber, and flow is effected from the second chamber through the second orifice into the third chamber in sheathing relation to the filamentary flow. Differential pressure effects the flow from first to third chamber independently but concurrently with positive displacement effecting flow from the second chamber into the third chamber.

Claims

1. Displacement metering apparatus with two independently metered flows, especially adapted for use with a particle sensing instrument, comprising:

first, second and third fluid chambers;

coaxially aligned orifices in communicating series relationship comprising a first orifice connecting said first and second chambers and a second orifice connecting said second and third chambers;

means for effecting and metering filamentary flow from said first chamber seriatim through said orifices into said third chamber;

means for concurrently effecting and metering flow from said second chamber in sheathing laminar relation to said filamentary fluid flow and through said second orifice into said third chamber,

said means for effecting filamentary flow comprising a first tube connecting a communication with said third chamber and a first piston slidably mounted in said first tube;

2. said means for effecting a sheathing flow comprising a second tube connecting a communication with said second chamber and a second piston slidably mounted in said second tube;

and

electric motor means connected to and concurrently operating said first and second pistons,

said electric motor means comprising an electric motor, and including a motor control connected to said electric motor,

said motor control comprising first means for energizing said electric motor to operate at a desired speed, second means for sensing a predetermined number of revolutions of said motor and generating a start signal for the particle sensing apparatus, third means for sensing a second predetermined number of revolutions after the start signal to generate a stop signal for the particle sensing apparatus, and fourth means connected to said first means for comparing actual motor speed with respect to the desired speed and causing said first means to adjust the energization of the motor.

4. Apparatus according to claim 2, comprising alarm means connected to and operated by said shut off means.

5. Apparatus according to claim 2, comprising pressure change detecting means connected to said pressure sensing means and to said shut off means for causing operation of said shut off means in response to detection of changes in pressure which are greater than a predetermined amount.

7. The improved apparatus of claim 5, including fixed walls between said chambers having said orifices therethrough in aligned space relation.

8. The improved apparatus of claim 5, wherein said flow control means comprises means for applying a suction to said third chamber to cause said first flow through said first and second orifices.

9. The improved apparatus of claim 5, wherein said flow control means comprises means for applying a pressure in said second chamber which is greater than the pressure in said third chamber to cause said sheathing second flow.

10. The improved apparatus of claim 5, wherein said flow control means comprises a suction connected to said third chamber and a device for automatically regulating and maintaining a pressure in said second chamber at a value intermediate an ambient pressure in said first chamber and the suction in said third chamber.

11. The improved apparatus of claim 5, wherein said flow control means comprises a mercury piston device for effecting both the first and second fluid flows.

12. The improved apparatus of claim 5, wherein said flow control means comprises a closed loop system including two of the three specified chambers.

13. The improved apparatus of claim 11, wherein said closed loop system comprises the second and third chambers.

14. The improved apparatus of claim 5, wherein said flow control means comprises a first tube connected in communication with said third chamber, a first piston slidably mounted in said first tube, a second tube connected in communication with said second chamber, a second piston slidably mounted in said second tube, and electric motor means connected to and concurrently operating said first and second pistons.

15. The improved apparatus of claim 13, wherein said electric motor means comprises a single motor mechanically linked to both of said first and second pistons.

16. The improved apparatus of claim 13, wherein said electric motor means comprises first and second electric motors connected to respective ones of said first and second pistons, and electric control means connected to said first and second motors for operating said motors in a predetermined speed relationship.

18. The improved method of claim 16 comprising the step of applying a suction to the third chamber to effect the filamentary flow.

19. The improved method of claim 16, comprising the step of applying a pressure to the second chamber relative the third chamber to displace fluid fron the second chamber in sheathing laminar relation to the filamentary fluid flow.

20. The improved method of claim 16, comprising the steps of applying a suction to the third chamber to cause the filamentary fluid flow and regulating and maintaining a pressure in the second chamber at a value intermediate an ambient pressure in the first chamber and the suction in the third chamber to effect the sheathing laminar fluid flow.

21. The improved method of claim 16, further defined by the step of operating a mercury piston device to establish pressure differentials from the first chamber to the second chamber to the third chamber to effect both the filamentary metering and fluid flow and the sheathing laminar metering and fluid flow.

22. The improved method of claim 16, further defined by concurrently metering and flowing fluid through a closed loop including the second and third chambers.

23. The improved method of claim 16, comprising the steps of operating an electric motor connected to a pair of pistons to effect both the filamentary and sheathing flows, and controlling the speed of the electric motor to provide constant flows during a predetermined period.

24. The improved method of claim 16, comprising the steps of operating a pair of electric motors connected to a pair of pistons, respectively, to effect the filamentary and sheathing flows, respectively, and controlling the speeds of the electric motors to provide constant flows during a predetermined period.

3. Displacement metering apparatus with two independently metered flows, especially adapted for use with a particle sensing instrument, comprising:

first, second and third fluid chambers;

coaxially aligned orifices in communicating series relationship comprising a first orifice connecting said first and second chambers and a second orifice connecting said second and third chambers;

means for effecting and metering filamentary flow from said first chamber seriatim through said orifices into said third chamber;

means for concurrently effecting and metering flow from said second chamber in sheathing laminar relation to said filamentary fluid flow and through said second orifice into said third chamber,

said means for effecting filamentary flow comprising a first tube connecting a communication with said third chamber and a first piston slidably mounted in said first tube,

said means for effecting a sheathing flow comprising a second tube connecting a communication with said second chamber and a second piston slidably mounted in said second tube; and

electric motor means connected to and concurrently operating said first and second pistons,

said first and second tubes including frangible material, and comprising pressure sensing means in one of said tubes for sensing the pressure therein, and shut off means connected to said pressure sensing means for causing deenergization of said electric motor means in response to a pressure greater than a predetermined limit.

6. In particle analysis apparatus of the type in which first, second and third fluid chambers are connected in fluid communication via interposed first and second orifices, and in which a filamentary first fluid flow is effected from the first chamber through the second chamber and into the third chamber, and a second fluid flow is effected from the second chamber into the third chamber in a sheathing laminar relation to the first flow to establish a total flow which is the sum of the first and second fluid flows, the improvement therein comprising:

flow control means for simultaneously and independently metering two of the three specified fluid flows so that each of said first and second fluid flows is a fixed fraction of said third fluid flow.

17. In a method of analyzing particles in which a filamentary fluid flow is effected from a first chamber through a first orifice, a second chamber and a second orifice into a third chamber, and a second fuid flow is effected from the second chamber through the second orifice into the third chamber in a sheathing laminar relation to the first flow to establish a total flow which is the sum of the first and second fluid flows, the improvement therein comprising:

simultaneously and independently metering two of the three specified fluid flows so that each of the first and second fluid flows is a fixed fraction of the third fluid flow.