Averaging pitot tube

• US 5,036,711 A
• Filed: 09/05/1989
• Issued: 08/06/1991
• Est. Priority Date: 09/05/1989
• Status: Expired due to Fees

• Current Assignee: Fred P. Good
• Original Assignee: Fred P. Good
• Inventors: Good, James E.
• Primary Examiner(s): Goldstein, Herbert
• Application Number:
  US07/402,913
• Time in Patent Office: 700 Days
• Field of Search: 73/861.42, 73/861.47, 73/861.65, 73/861.66, 73/861.67
• US Class Current: 73/861.66
• CPC Class Codes: G01F 1/46 Pitot tubes
• CPC Class Codes: G01L 19/0015 using switching means

Abstract

An averaging pitot tube for measuring fluid flow in a pipe or conduit, is disclosed, including an integral head connected by a transition to a sensing tube or probe. The probe is insertable through the conduit or pipe in which fluid flow occurs to measure an upstream high pressure and a downstream low pressure. Upstream holes are formed in the probe to communicate high pressure into a high pressure chamber in the probe. Downstream holes are also formed in the probe to communicate a low pressure into a low pressure chamber in the probe. Valves placed in the integral head selectively open and close the high and low pressure passageways that communicate with the high and low pressure chambers. A measurement device is selectively connectable to the integral head and is in fluid communication with said high and low pressure passageways to make measurements of flow dependent upon the difference between the high and low pressure. Tube fittings placed in the head are disclosed for reducing leaks in the system.

Claims

1. In an averaging pitot tube for measuring high pressure and low pressure in a fluid flowing in a closed conduit, said pitot tube including a probe insertable into said conduit having an upstream surface and a downstream surface each of which has a plurality of holes formed along the length thereof for measuring respectively high pressure and low pressure, the improvement comprising:

a cross-section of said probe including an essentially rounded upstream surface and slightly angularly diverging lateral side surfaces interconnected by a rear surface, said rounded surface including a roughened area of pre determined size.

2. The invention as defined in claim 1 further including:

a mounting system, which provides a fluid-tight connection and maintains the probe in contact with an opposite wall of the conduit regardless of changes in conduit diameter due to changes in pressure, temperature or mechanical force.

3. The invention as defined in claim 1 wherein said side surfaces define an angle of approximately 5°

with a longitudinal centerline of the probe.

4. An averaging pitot tube measuring a high pressure and a low pressure in a closed conduit having fluid flowing therealong in a predetermined direction, comprising in combination:

an instrument head integrally connected to a probe, which probe is insertable into said conduit and extends across the fluid flow in said conduit, said probe including a rounded, roughened, upstream surface to minimize the thickness of boundary layer fluid flow, said probe further including slightly diverging lateral sides, a plurality of holes formed along the length of the rounded surface, a downstream surface of said probe located in a low pressure zone of the fluid flow, said downstream surface including similar holes formed along the length thereof, said probe including a high pressure chamber and a low pressure chamber in fluid communication with passageways formed in said head, said passageways in said head in fluid communication with measurement devices connectable to said head.

5. The invention as defined in claim 4 wherein said probe further includes a tube of a generally round-shaped cross section facing the direction of fluid flow defining the high pressure chamber, and a generally "u" shaped tube attached to the back of the round tube defining the low pressure chamber.

6. An averaging pitot tube for connection to a fluid conduit to measure an upstream high pressure and a downstream low pressure, comprising in combination:

a head integrally connected to said probe, said probe having openings formed on a rounded, upstream surface, said upstream surface roughened over a predetermined area and having openings formed therethrough associated with high pressure measurements and a downstream surface of said probe associated with a low pressure measurement, angularly divergent lateral side surfaces interconnecting said upstream and downstream surfaces to maintain a constant flow coefficient, said openings providing fluid communication with a high pressure chamber and a low pressure chamber, respectively, in said probe, said head providing fluid flow communication between said high and low pressure chambers by means of high and low pressure passageways which are selectively opened and closed by high pressure and low pressure valves, outlet ports of said head registering with and in fluid communication with inlet ports of a measurement device, which is selectively connected to said head, whereby said measurement device is connected to said pitot tube for fluid flow measurements.

7. In an averaging pitot tube for measuring high pressure and low pressure in a fluid flowing in a closed conduit, said pitot tube including a probe insertable into said conduit, an upstream surface and a downstream surface of said probe, each having a plurality of holes formed along the length thereof for measuring high pressure and low pressure, respectively, the improvement comprising:

a mounting system including a tubular sleeve to receive said probe, a ring mounted on said probe, a spring coaxial about said probe and abutting at one end a follower and packing material, which packing material is mounted on said ring, a packing nut threadably received by said sleeve abutting a second end of said spring through a second follower and a lock nut to secure the position of said mounting system, whereby said mounting system provides a fluid-tight connection and maintains the probe in contact with an opposite wall of the conduit, regardless of changes in conduit diameter due to changes in pressure, temperature or mechanical force.

8. An averaging pitot tube for measuring a high pressure and a low pressure in a closed conduit having fluid flowing therealong in a predetermined direction, comprising in combination:

an instrument head integrally connected to a probe, which probe is insertable into said conduit and extends across the fluid flow in said conduit, said probe including a roughened and rounded upstream surface to minimize thickness of boundary layer fluid flow, and slightly diverging lateral sides, said roughened and rounded surface including a plurality of holes formed along the length thereof, said probe further including a downstream surface in a low pressure zone of the fluid flow, said downstream surface including similar holes formed along the length thereof, said probe including a high pressure chamber and a low pressure chamber fluid communication with passageways formed in said head, said passageways in said head in fluid communication with measurement devices selectively connectable to said head.

9. The invention as defined in claim 8 wherein said head further includes high and low pressure passageways associated with each of said high pressure and low pressure chambers, said passageway selectively closed and opened by first and second valves.

10. The invention as defined in claim 9 further including an intermediate passageway formed in said head, said intermediate passageway selectively opened and closed by a third valve, to thereby provide fluid communication between the high pressure passageway and the low pressure passageway.

11. The invention as defined in claim 8 wherein said probe further includes a tube of generally round shaped cross-section facing the direction of fluid flow defining the high pressure chamber and a generally U-shaped tube attached to the back of the round tube defining the low pressure chamber.

12. The invention as defined in claim 8 wherein a vent is formed through said probe for each of said high and low pressure chambers, and a faring interconnecting said instrument head forming a volume into which high pressure and low pressure fluids respectively pass through said vent and into said passageways, a transition sleeve fitting around said probe, said transition fixedly connected to said head and said faring and extending to a wall of said conduit.

13. An averaging pitot tube for connection to a fluid conduit to measure an upstream high pressure and a downstream low pressure, comprising in combination:

a head integrally connected to said probe, said probe having openings formed in an upstream surface thereof associated with a high pressure measurement and openings formed in a downstream surface thereof associated with a low pressure measurement, said openings providing fluid communication with a high pressure chamber and a low pressure chamber in said probe, said head providing fluid flow communication between said high and low pressure chambers by means of high and low pressure passageways which are selectively opened and closed by high pressure and low pressure valves, outlet ports of said head register with and are in fluid communications with inlet ports of a measurement device selectively connected to said head, said probe further including a rounded upstream surface and angularly divergent lateral side surfaces and a rear surface, whereby boundary layer flow occurs around said probe and separates from said probe along said lateral side surfaces to thereby maintain a constant flow coefficient.

14. The invention as defined in claim 13 wherein said rounded front surface of said probe is roughed over a predetermined area.