Detection and quantification of fluid leaks

• US 5,535,136 A
• Filed: 05/17/1994
• Issued: 07/09/1996
• Est. Priority Date: 05/17/1994
• Status: Expired due to Term

• Current Assignee: Larry R. Standifer
• Original Assignee: Larry R. Standifer
• Inventors: Standifer, Larry R.
• Primary Examiner(s): Cosimano, Edward R.
• Application Number:
  US08/243,916
• Time in Patent Office: 784 Days
• Field of Search: 73/40, 73/40.5 R, 73/40.5 A, 73/592, 364/509, 364/510
• US Class Current: 702/51
• CPC Class Codes: G01M 3/007 Leak detector calibration, standard leaks G01M3/207 takes precedence
• CPC Class Codes: G01M 3/24 using infrasonic, sonic, or ultrasonic vibrations
• CPC Class Codes: G01M 3/243 for pipes

Abstract

An apparatus and a method for quantifying the leak flow rate of a fluid from a fluid leak site in a piping system. An ultrasonic sound detector is used to accumulate sound level data for known leak sites in known piping system elements through which a known fluid flows at known temperatures and pressures. The accumulated data provide a database to permit the determination of gas leakage rates in actual piping systems by comparing test data obtained for the actual piping system with the data contained in the database. Based upon the cost of the fluid, the annual costs for fluid lost as a result of leakage can be determined, as well as the annual volume of fluid lost.

Claims

1. A method for providing a database for use in determining the flow rate of a fluid at a leak site in a pressurized fluid system, said method comprising the steps of:

a) deriving attenuation level values corresponding to sound pressure level values for fluid leaks from known piping elements of known fluids at known pressures, temperatures, and leakage flow rates;

b) calculating an effective leakage site flow area corresponding with the derived attenuation level values; and

c) storing the derived attenuation levels and leakage site flow areas for the corresponding system elements and fluid conditions to provide a database for use in determining leakage flow areas and leakage flow rates in actual piping systems from measured sound pressure levels.

2. The method of claim 1 wherein the step of deriving attenuation level values includes operating a sound detector at a predetermined distance from said leak site.

3. The method of claim 2 wherein said predetermined distance is at least about six inches.

4. The method of claim 3 wherein said predetermined distance is twelve inches.

5. The method of claim 1 wherein said known piping elements are of different sizes.

6. The method of claim 1 wherein said known piping elements are selected from the group consisting of:

screwed pipe connections, flanged pipe connections, tube fittings, union fittings, valve fittings, misaligned union fittings, and straight-line piping.

7. The method of claim 1 wherein said known fluids are selected from the group consisting of:

air, helium, argon, nitrogen, natural gas, hydrogen, oxygen, and steam.

8. A method for determining the rate of fluid leakage from a leakage site in a pressurized fluid system, said method comprising the steps of:

a) providing a database containing base attenuation levels and corresponding leakage site flow areas for known piping system elements containing known fluids at known pressures and temperatures, said base attenuation levels corresponding to attenuated sound pressure levels;

b) measuring the maximum sound pressure level at said leakage site;

c) attenuating the measured sound pressure level to a predetermined level;

d) measuring the attenuation level associated with step (c);

e) comparing the measured attenuation level at said leakage site with the base attenuation levels contained in the database for a corresponding piping element and a corresponding fluid at a corresponding pressure and temperature, to identify an effective leakage site flow area that corresponds with the measured attenuation level; and

f) calculating the flow rate of fluid leakage from the effective leakage site flow area and pressure and temperature of the fluid within the fluid system.

9. The method of claim 8, further including the step of detecting leakage sites by passing a sound pressure level meter along the fluid system to identify leakage sites by sound pressure level.

10. The method of claim 8 wherein the step of measuring the maximum sound pressure level at a leakage site is performed at a predetermined distance from said leakage site.

11. The method of claim 10 wherein said predetermined distance is at least about six inches.

12. The method of claim 11 wherein said predetermined distance is twelve inches.

13. An apparatus for determining the rate of fluid leakage from a leakage site in a pressurized fluid system, said apparatus comprising:

a) a digital computer containing a database including base sound pressure attenuation levels and corresponding leakage site flow areas for known piping system elements containing known fluids at known pressures and temperatures;

b) a sound pressure level meter for detecting a leakage site in the fluid system based upon sound emanating from the leakage site and for measuring the maximum sound pressure level at the leakage site;

c) input means for inputting a measured sound pressure attenuation value and corresponding piping system element information and fluid condition information;

d) program means for calculating leakage flow rate at each leakage site based upon the measured sound pressure attenuation value at the leakage site; and

e) display means for displaying the calculated leakage flow rate at each leakage site.

14. An apparatus for determining the rate of fluid leakage from a leakage site in a pressurized fluid system comprising:

a) means for measuring the sound pressure level of said fluid leakage;

b) means for attenuating the sound pressure level measured in step (a);

c) means for measuring the level of attenuation obtained in step (b);

d) means for comparing the attenuation level measured to a known standard for fluid leakage rates; and

e) means for calculating the flow rate of fluid leakage based on the comparison performed in step (d).