Electronic pressure gauge and flow meter

• US 4,586,383 A
• Filed: 09/13/1982
• Issued: 05/06/1986
• Est. Priority Date: 09/13/1982
• Status: Expired due to Fees

• Current Assignee: George W. Blomquist
• Original Assignee: George W. Blomquist
• Inventors: Blomquist, George W.
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US06/417,454
• Time in Patent Office: 1,331 Days
• Field of Search: 73/706, 73/707, 73/708, 73/716-722, 73/723-731, 73/715, 73/756, 374/201, 374/202, 374/203, 374/188
• US Class Current: 73/706
• CPC Class Codes: G01F 15/185 Connecting means, e.g. bypass conduits
• CPC Class Codes: G01K 13/02 for measuring temperature of moving fluids or granular materials capable of flow
• CPC Class Codes: G01L 19/0007 Fluidic connecting means
• CPC Class Codes: G01L 19/0046 using isolation membranes G01L13/026 and G01L19/0645 take precedence
• CPC Class Codes: G01L 9/0026 Transmitting or indicating the displacement of flexible, deformable tubes by electric, electromechanical, magnetic or electromagnetic means G01L9/0008 takes precedence

Abstract

A pressure gauge includes a cylindrical member having a flexible plate covering one end. Center flex of the plate is used to measure the force applied by fluid pressure. A low pressure transducer electrically measures the applied force. Pressure is transmitted from the flexible plate to the transducer by hydraulic fluid enclosed in the cylinder by a plastic boot. The boot is sealed to the cylinder by a sweat fit between the cylinder and a coaxial collar. The range of forces that can be measured is controlled by the thickness and diameter of the plate. In addition to pressure, the gauge can be used to measure temperature and orifice opening, and provide an indication of volumetric flow of the fluid.

Claims

1. Apparatus for measuring a parameter of a fluid comprising:

an adapter for providing an output signal having a pressure related to a parameter being measured;

a transducer for providing an electrical output signal having a value indicative of a pressure applied thereto;

plural means for modifying the adapter output signal to a value directly proportional to said output signal, each of the plural means having a different proportionality between the adapter output signal and the modified signal, and

means connecting at least one of said plural means between said adapter and said transducer, including means for applying to said transducer a modified signal that is within the operating range of said transducer, said connecting means enabling said one of said plural means to be removed from between said adapter and said transducer and a different one of said plural means to be substituted therefor.

2. The apparatus of claim 1 wherein said plural means for modifying each comprises a housing having a cavity filled with a substantially non-compressible fluid, and a flexible wall on each of two opposite sides of said cavity.

3. The apparatus of claim 2 wherein said housing includes a cylinder having an axial recess therein and one of said flexible walls is provided by a flexible diaphragm over said recess at one end of said cylinder.

4. The apparatus of claim 3 wherein the other flexible wall is provided by an end face of said cylinder.

5. The apparatus of claim 3 wherein said recess extends through said cylinder, and the other flexible wall is provided by a flexible plate disposed at the other end of said cylinder.

6. The apparatus of claim 5 further including an apertured plate disposed within said recess adjacent said flexible diaphragm.

7. The apparatus of claim 5 or 6 further including a flexible cup disposed within said recess to prevent fluid from leaking past said flexible plate.

8. The apparatus of claim 3 further including a protective wafer attached to said flexible diaphragm on the side opposite said recess.

9. The apparatus of claim 3 further including a threaded coupling fitted to the exterior of said cylinder, and wherein said flexible diaphragm extends around the side of said cylinder and is disposed between said cylinder and said coupling.

10. The apparatus of claim 2 wherein said housing includes a cylinder having an axial bore therethrough, and one of said flexible walls is provided by a flexible plate disposed at one end of said cylinder.

11. The apparatus of claim 10 further including a flexible cup disposed within said bore to prevent fluid from leaking past said flexible plate.

12. The apparatus of claim 11 further including a threaded coupling fitted to the exterior of said cylinder, and wherein said flexible cup extends around the side of said cylinder and is disposed between said cylinder and said coupling.

13. The apparatus of claim 10 further including an apertured plate disposed in said bore at the other end of said cylinder.

14. The apparatus of claim 3 or 10 wherein said cylinder is provided with external threads and said connecting means includes an internally threaded coupling housing for connecting two of said cylinders in series, said coupling housing being filled with said substantially non-compressible fluid so that a pressure signal applied to the flexible wall of one cylinder connected to said coupling housing is transmitted to another cylinder connected to said coupling housing and appears as a modified pressure signal at the flexible wall thereof that is exterior to said coupling housing.

15. The apparatus of claim 14 wherein said coupling housing includes means for measuring the temperature of said non-compressible fluid.

16. The apparatus of claim 15 where said measuring means comprises a thermistor.

17. The apparatus of claim 14 wherein said coupling housing includes a bleed valve for permitting excess fluid to be vented from said coupling housing.

18. The apparatus of claim 2 wherein said means for applying the modified signal to said transducer includes a primary interface member in engagement with one of said flexible walls, a base plate on the side of said primary interface member opposite said flexible wall, a top plate engaging one face of said transducer, and a secondary interface member disposed between said base plate and said top plate.

19. The apparatus of claim 18 wherein said secondary interface member is flexible.

20. The apparatus of claim 19 wherein said secondary interface member comprises a spring.

21. The apparatus of claim 18 wherein said secondary interface member is a non-compressible body.

22. The apparatus of claim 18 further including an interface housing for said transducer and said applying means, said interface housing including nulling means engaging the opposite face of said transducer for applying an adjustable pressure thereto.

23. The apparatus of claim 22 wherein said nulling means comprises a manually adjustable threaded knob.

24. The apparatus of claim 22 wherein said nulling means is remotely adjustable.

25. The apparatus of claim 24 wherein said nulling means comprises a nulling plate engaging said opposite face of said transducer, ratchet lock means disposed between said nulling plate and said interface housing, a piston engaging said nulling plate, and remotely controlled means for applying a fluid pressure to said piston.

26. The apparatus of claim 25 wherein said remotely controlled means for applying fluid pressure includes a cylinder in which said piston is disposed, a pressurized fluid reservoir in fluid communication with said cylinder, and a solenoid operated valve for selectively connecting said reservoir and said cylinder.

27. The apparatus of claim 2 including at least one ring disposed within said cavity between said flexible walls.

28. The apparatus of claim 1 wherein the parameter to be measured is the pressure of the fluid, and said adapter comprises means for providing fluid communication between a container in which said fluid is disposed and said modifying means.

29. The apparatus of claim 1 wherein the parameter to be measured is the temperature of the fluid, and said adapter comprises a fluid filled probe, said probe having a flexible diaphragm at one end thereof for providing spatial displacement in dependence upon expansion and contraction of the fluid in said probe related to variations in temperature.

30. The apparatus of claim 29 wherein said probe is filled with an alcohol medium.

31. The apparatus of claim 29 wherein said probe is filled with mercury.

32. The apparatus of claim 29 wherein said probe is filled with an inert gas.

33. The apparatus of claim 1 wherin the parameter to be measured is the volume of fluid passing through a dump valve, and said adapter includes a flexible interface member disposed between said dump valve and said modifying means.

34. The apparatus of claim 33 wherein said flexible interface member comprises a spring.

35. The apparatus of claim 34 further including means for limiting movement of said dump valve to thereby limit maximum compression of said spring.

36. The apparatus of claim 1 including means for multiplying said electrical output signal by a scaler factor related to the parameter being measured and displaying the resulting product, and means for entering a value related to a range of values of the parameter being measured.

37. The apparatus of claim 36 wherein the entered value is a midpoint value for said range.

38. The apparatus of claim 36 further including means for correcting said electrical output signal for standard temperature and pressure conditions.

39. The apparatus of claim 36 including processing circuits for providing indications of each of the pressure and temperature of a fluid and the opening of a valve and further including means for combining these indications to provide a display related to the flow of the fluid.

40. The apparatus of claim 1 wherein said plural means for modifying include a Bourdon tube.