System and method for determining a density of a fluid

• US 6,234,019 B1
• Filed: 02/19/1999
• Issued: 05/22/2001
• Est. Priority Date: 02/19/1999
• Status: Expired due to Term

• Current Assignee: Smar Research Corp.
• Original Assignee: Smar Research Corp.
• Inventors: Caldeira, Gilmar M.
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US09/253,830
• Time in Patent Office: 823 Days
• Field of Search: 734/37, 734/39, 73/32.R, 734/34, 702/137, 702/138
• US Class Current: 73/438
• CPC Class Codes: G01N 9/26 by measuring pressure differences

Abstract

A system and method for obtaining a fluid density of a fluid in a tank includes, for example, a first sensor coupled to a second sensor through an extension. The two sensors are coupled to a transmitter. The sensors are lowered into the fluid of the tank such that the first sensor is positioned at a first fluid level and the second sensor is positioned at a second fluid level. Fluid pressure at the two levels is sensed by the two sensors which affects the fluid pressure of a fill fluid inside the housing of the system. The effect on the fluid pressure of the fill fluid is sensed by the transmitter which creates an electrical signal relating to the fluid pressures sensed by the two sensors. A calculating device may determine the fluid density of the fluid in the tank from the signal received from the transmitter.

Claims

1. A system for determining a density of a sample fluid in a tank, comprising:

a sensor fluid housing situated within the tank and containing a first substantially static sensor fluid and a second substantially static sensor fluid, the sensor fluid housing maintaining the first and second sensor fluids separate from the sample fluid;

a first sensor situated within the tank, the first sensor being coupled to the sensor fluid housing, the first sensor disposed in the tank at a first fluid level of the sample fluid, the first sensor detecting a first fluid pressure at the first fluid level by acting on the first substantially static sensor fluid;

a second sensor situated within the tank, the second sensor being coupled to the sensor fluid housing, the second sensor disposed in the tank at a second fluid level of the sample fluid, the second sensor detecting a second fluid pressure at the second fluid level by acting on the second substantially static sensor fluid, the second sensor being positioned at a predetermined distance from the first sensor; and

a transmitter communicating with the first sensor via the first substantially static sensor fluid and communicating with the second sensor via the second substantially static sensor fluid, the transmitter generating at least one signal corresponding to the density of the sample fluid, the at least one signal being generated as a function of the first fluid pressure and the second fluid pressure.

2. The system according to claim 1, further comprising:

a calculating device coupled to the transmitter, the calculating device calculating the density of the sample fluid in the tank as a function of the at least one signal received from the transmitter.

3. The system according to claim 2, wherein the calculating device is a computer system.

4. The system according to claim 3, wherein the transmitter is coupled to the computer system via a first data bus and a second data bus.

5. The system according to claim 3, wherein the transmitter and the computer system communicate with one another using a wireless communications arrangement.

6. The system according to claim 1, wherein a housing fluid is composed of the first substantially static sensor fluid and the second substantially static sensor fluid.

7. The system according to claim 1, wherein the first substantially static sensor fluid includes at least one of a silicone oil, a fluorolube oil and a propylene glycol oil.

8. The system according to claim 1, wherein the second substantially static sensor fluid includes at least one of a silicone oil, a fluorolube oil and a propylene glycol oil.

9. The system according to claim 1, wherein the first substantially static sensor fluid is at least partially provided in a first tube of the sensor fluid housing, the first tube extending from the first sensor to the transmitter.

10. The system according to claim 1, wherein the second substantially static sensor fluid is at least partially provided in a second tube of the sensor fluid housing, the second tube extending from the first sensor to the transmitter.

11. The system according to claim 1,

wherein the first sensor includes a first sensor housing situated within the tank and a first set of at least two diaphragms coupled to the first sensor housing, and

wherein the second sensor includes a second sensor housing situated within the tank and a second set of at least two diaphragms coupled to the first sensor housing.

12. The system according to claim 11,

wherein the first sensor housing has a cylindrical shape,

wherein the first set includes a first diaphragm and a second diaphragm, and

wherein the first diaphragm is mounted within the first sensor housing at a first edge, and the second diaphragm is mounted within the first sensor housing at a second edge, the first edge being provided opposite to the second edge.

13. The system according to claim 11,

wherein the second sensor housing has a cylindrical shape,

wherein the second set includes a first diaphragm and a second diaphragm, and

wherein the first diaphragm is mounted within the second sensor housing at a first edge, and the second diaphragm is mounted within the second sensor housing at a second edge, the first edge being provided opposite to the second edge.

14. The system according to claim 11, wherein each of the at least two diaphragms of the first set acts on the first substantially static sensor fluid to displace the first substantially static sensor fluid.

15. The system according to claim 11, wherein each of the at least two diaphragms of the second set acts on the second substantially static sensor fluid to displace the second substantially static sensor fluid.

16. The system according to claim 11,

wherein the first sensor housing has a triangular prism shape, and

wherein the first set of at least two diaphragms includes at least three diaphragms, each of the at least three diaphragms being mounted on a separate side of the first sensor housing.

17. The system according to claim 11,

wherein the second sensor housing has a triangular prism shape, and

wherein the second set of at least two diaphragms includes at least three diaphragms, each of the at least three diaphragms being mounted on a separate side of the second sensor housing.

18. The system according to claim 11, wherein each diaphragm in the first and second sets of at least two diaphragms has at least one concentric flexible portion.

19. The system according to claim 1, wherein each of the first and second sensors has an approximately spherical shape and includes a sensor housing and at least one diaphragm substantially covering a surface of the approximately spherical shape.

20. The system according to claim 1, wherein the first sensor and the second sensor are mounted to the sensor fluid housing.

21. The system according to claim 1, wherein the first sensor and the second sensor are integral with the sensor fluid housing.

22. A system for determining a density of a sample fluid in a tank, comprising:

a sensor housing situated within the tank;

a first sensor situated within the tank coupled to the housing via a first extension situated within the tank;

a second sensor situated within the tank coupled to the housing via a second extension situated within the tank, the first sensor positioned at a first fluid level of the sample fluid and sensing a first fluid pressure at the first fluid level by providing a first substantially static sensor fluid via the first extension, the second sensor positioned at a second fluid level of the sample fluid and sensing a second fluid pressure at the second fluid by providing a second substantially static sensor fluid via the second extension, the second fluid level being different from the first fluid level; and

a transmitter provided in the housing, the transmitter being in fluid communication with the first sensor via the first substantially static sensor fluid in the first extension, and being in fluid communication with the second sensor via the second substantially static sensor fluid in the second extension, the transmitter generating at least one signal which relates to the first and second fluid pressures;

wherein the first and second substantially static sensor fluids are maintained separately from the sample fluid by the housing.

23. The system according to claim 22, wherein the first extension and the second extension are aligned along a same longitudinal axis.

24. The system according to claim 22, wherein the first extension and the second extension extend at different longitudinal axes.

25. The system according to claim 22, further comprising:

a calculating device coupled to the transmitter, the calculating device calculating the fluid density of the sample fluid in the tank as a function of the at least one signal received from the transmitter.

26. A sensor for determining a pressure of a sample fluid, comprising:

a sensor housing having a substantially static sensor fluid; and

at least two diaphragms provided in the sensor housing, each of the at least two diaphragms acting on the substantially static sensor fluid in response to the pressure provided by the sample fluid.

27. The sensor according to claim 26, wherein the sensor housing includes a portion for displacing the substantially static sensor fluid in the sensor when the at least two diaphragms act on the substantially static sensor fluid.

28. The sensor according to claim 26,

wherein the sensor housing has a cylindrical shape, and

wherein the at least two diaphragms include a first and a second diaphragm, the first diaphragm being mounted within the sensor housing at a first edge, the second diaphragm being mounted at a second edge, the first edge being opposite to the second edge.

29. The sensor according to claim 26,

wherein the sensor housing has a triangular prism shape, and

wherein the at least two diaphragms include at least three diaphragms, each of the three diaphragms being mounted on a separate side of the sensor housing.

30. The sensor according to claim 26, wherein each of the at least two diaphragms has at least one concentric flexible portion.

31. The sensor according to claim 30, wherein each of the at least one concentric flexible portions has at least one of a circular shape and a polygonal shape.

32. The sensor according to claim 26, wherein the sensor housing has an approximately spherical shape.

33. The sensor according to claim 26, wherein the sensor is composed of at least one of a stainless steel material, a hastelloy material, a Monel material, a tantalum material and a titanium material.

34. A sensor for determining a pressure of a sample fluid, comprising:

a sensor housing having an approximately spherical shape, the sensor housing enclosing a substantially static sensor fluid; and

at least one diaphragm coupled to the sensor housing, the at least one diaphragm acting on the substantially static sensor fluid in response to the pressure provided by the sample fluid.

35. A method for determining a density of a sample fluid in a tank, comprising the steps of:

providing a first sensor situated within the tank at a first fluid level in the sample fluid;

providing a second sensor situated within the tank at a second fluid level in the sample fluid, the second fluid level being different from the first fluid level;

sensing a first fluid pressure of the sample fluid at the first fluid level using the first sensor to act on a first substantially static sensor fluid, the first substantially static sensor fluid being maintained separately from the sample fluid, and the first sensor communicating with a transmitter using the first substantially static sensor fluid;

sensing a second fluid pressure of the sample fluid at the second fluid level using a second sensor to act on a second substantially static sensor fluid, the second substantially static sensor fluid being maintained separately from the sample fluid, and the second sensor communicating with the transmitter through the second substantially static sensor fluid; and

generating at least one signal relating to the first fluid pressure and the second fluid pressure to determine the density of the particular fluid.

36. The method according to claim 35, further comprising the step of:

determining the density of the particular fluid in the tank as a function of the at least one signal.

37. The method according to claim 35, wherein the step of sensing the first fluid pressure includes the substep of applying the first fluid pressure to at least two diaphrams which are coupled to the first sensor, the at least two diaphragms bending to displace the first substantially static sensor fluid in the first sensor.

38. The method according to claim 35, wherein the step of sensing the second fluid pressure includes the substep of applying the second fluid pressure to at least two diaphrams which are coupled to the second sensor, the at least two diaphragms bending to displace the second substantially static sensor fluid in the second sensor.

39. The method according to claim 35, wherein the first and second sensors are maintained at a predetermined distance from one another by coupling the first sensor to a first end of an extension member and the second sensor to a second end of the extension member.

40. A method for measuring a fluid pressure of a sample fluid, comprising the steps of:

providing a sensor situated within the sample fluid at a fluid level, the sensor including a sensor housing, at least two diaphragms and a substantially static sensor fluid, the at least two diaphragms being coupled to the sensor housing, the at least two diaphragms being affected by the fluid pressure of the fluid level, the at least two diaphragms acting on the substantially static sensor fluid; and

determining the fluid pressure of the fluid at the fluid level by measuring the fluid pressure of the substantially static sensor fluid;

wherein the substantially static sensor fluid and the sample fluid are maintained separately from one another.

41. A sensor for determining a pressure of a sample fluid, comprising:

a sensor housing containing a substantially static sensor fluid; and

at least one diaphragm disposed in the sensor housing and acting on the substantially static sensor fluid in response to the pressure provided by the sample fluid,

wherein the substantially static sensor fluid and the sample fluid are maintained separately from one another and the at least one diaphragm includes a concentric flexible portion having a non-circular shape.

42. The sensor according to claim 41, wherein the concentric flexible portion has a polygonal shape.

43. The sensor according to claim 41, wherein the concentric flexible portion has a substantially rectangular shape.

44. The sensor according to claim 41, wherein the concentric flexible portion has an indentation portion which extends in a non-circular manner along an edge of the at least one diaghram.