Method and apparatus for detecting a break or other occurrence in a pipeline containing gas under pressure

• US 3,903,729 A
• Filed: 04/09/1973
• Issued: 09/09/1975
• Est. Priority Date: 12/30/1970
• Status: Expired due to Term

• Current Assignee: CRC Bethany International Inc.
• Original Assignee: Morris T. Covington
• Inventors: Covington, Morris T.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US05/349,422
• Time in Patent Office: 883 Days
• Field of Search: 73/4.5A,4.5R,69,67.9,67.7,71.4,194A 340/18NC 181/.5,125
• US Class Current: 73/40.50R
• CPC Class Codes: F16L 2101/30 Inspecting, measuring or testing
• CPC Class Codes: F17D 5/06 using electric or acoustic means
• CPC Class Codes: G01M 3/243 for pipes
• CPC Class Codes: G01M 3/2815 using pressure measurements

Abstract

A method and apparatus for rapidly detecting a break or other occurrence in a pipeline containing gas under pressure by detecting the adiabatic pressure wave generated in the gas by the break and propagated through the gas at the speed of sound. A method and apparatus for determining the distance between the break in the gas pipeline and the detection location by determining the change of pressure with respect to time of the leading edge of the adiabatic pressure wave. A method and apparatus for detecting a break or other occurrence in a pipeline containing a gas under pressure which pipeline is connected by a compression station or pumping station or the like, by detecting the compressional waves traveling in a preselected direction through the gas without substantial interference from compressional waves traveling in the opposite direction. Spaced pressure/electrical transducers are utilized to detect the compressional waves. Electronic circuitry is utilized to delay a selected one of the transduced electrical signals for a selected time interval to substantially eliminate the portion of the signal responsive to compressional waves traveling in the direction opposite the preselected direction.

Claims

1. In a pipeline containing gas under pressure, the method of rapidly detecting at a selected stationary monitoring point in the gas the existence of a distantly occurring break or other occurrence in the pipeline, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, including the steps of:

continuously transducing transient changes of the pressure of the gas at the monitoring point in the gas into an electrical signal proportional thereto;

continuously monitoring the electrical signal and detecting the portion thereof representative of at least the leading edge of the adiabatic pressure wave created in the gas by the break or other occurrence and propagated through the gas at the speed of sound; and

responsive to the detection of the portion of the electrical signal representative of the leading edge of the adiabatic pressure wave, activating means indicative of the existence of the break or other occurrence.

2. In a pipeline containing gas under pressure, the method of rapidly detecting the existence of a break or other occurrence in the pipeline in accordance with claim 1 and of rapidly determining the distance along the pipeline from the monitoring point to the break or other occurrence, including the additional step of:

determining from the portion of the electrical signal representative of the leading edge of the adiabatic pressure wave, the rate of change of the pressure of the gas at the monitoring point during at least a portion of the time the pressure of the gas changed adiabatically responsive to the passing of the adiabatic pressure wave.

3. In a pipeline containing gas under pressure, the method of rapidly detecting the existence of a break or other occurence in the pipeline and of rapidly determining the distance along the pipeline from the monitoring point to the break or other occurence, according to claim 2 and including the additional step of:

solving the following equation to determine the distance along the pipeline from the monitoring point to the break or other occurrence;

4. In a pipeline containing gas under pressure, in which the gas experiences transient changes in pressure at a selected stationary monitoring point due to noise or the like occurring along the pipeline in a selected direction from the monitoring point, the method of rapidly detecting at the monitoring point the existence of a break occurring distantly along the pipeline in the opposite direction from the monitoring point, which break produces a rapid and significant decrease in the pressure of the gas at the point of the break and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, and of determining the distance along the pipeline between the monitoring point and the break, including the steps of:

continuously transducing transient changes of the pressure of the gas at the monitoring point into an electrical signal proportional thereto;

modifying the electrical signal to substantially eliminate the portion thereof representative of the transient changes in the pressure of the gas caused by the noise or the like occurring along the pipeline in the selected direction from the monitoring point;

continuously monitoring the modified electrical signal and detecting the portion thereof representative of at least the leading edge of the adiabatic pressure wave created in the gas by the break and propagated through the gas at the speed of sound; and

determining from the portion of the modified electrical signal representative of the leading edge of the adiabatic pressure wave, the rate of change of the pressure of the gas at the monitoring point during at least a portion of the time the pressure of the gas changed adiabatically responsive to the passing of the adiabatic pressure wave.

5. In a pipeline system including a pipeline containing gas under pressure and extending from a compression station or the like which causes transient changes in the pressure of the gas at a first stationary monitoring point in the gas in the vicinity of the compression station, the method of rapidly detecting a break or other occurrence in the pipeline occurring along the pipeline on the opposite side of the first monitoring point from the compression station, which break or other occurence produces a rapid and signficiant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, wherein the transient changes in the pressure of the gas caused by the compression station are prevented from substantially interfering with the detection of the break or other occurrence, including the steps of:

detecting changes in the pressure of the gas at the first monitoring point in the gas and generating a first electrical signal proportional thereto;

detecting changes in the pressure of the gas at a second stationary monitoring point in the gas a selected distance from the first monitoring point along the pipeline toward the compression station and generating a second electrical signal proportional thereto;

delaying the second electrical signAl for a period of time substantially equal to the distance along the pipeline between the first and second monitoring points divided by the speed of sound in the gas;

comparing the first electrical signal and the delayed second electrical signal and producing a third electrical signal which is representative of at least the leading edge of the adiabatic pressure wave created in the gas by the break or other occurence and propagated through the gas;

monitoring the third electrical signal and detecting the portions thereof representative of the leading edge of the adiabatic pressure wave created in the gas by the break or other occurrence and propagated through the gas; and

responsive to the detection of such leading edge of the adiabatic pressure wave, activating means indicating the existence of the break or other occurrence.

6. In a pipeline system including a pipeline containing gas under pressure and extending from a compression station or the like which causes transient changes in the pressure of the gas at a first stationary monitoring point in the gas in the vicinity of the compression station, the method of rapidly detecting a break or other occurrence in the pipeline occurring somewhere along the pipeline on the other side of the monitoring point from the compression station, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, wherein the transient changes in the pressure of the gas caused by the compression station are prevented from substantially interefering with the detection of the break or other occurrence, and of determining the distance between the break and the first monitoring point, according to claim 5 and including the additional steps of:

determining the change in pressure with respect to time of the substantially linear portion of the third electrical signal representative of the leading edge of the adiabatic pressure wave; and

solving the following equation;

7. In a gas conductor containing gas under pressure, the method of rapidly detecting and indicating the existence of a break in the conductor occurring somewhere along the conductor in a selected direction from a reference position, which break produces a rapid and significant decrease in the pressure of the gas at the point of the break and causes a compressional wave to be propagated through the gas in both directions from the break at the speed of sound, including the steps of:

detecting transient changes in the pressure of the gas at a first stationary point in the gas at the reference position;

detecting transient changes in the pressure of the gas at a second stationary point in the gas, the second point being loCated a known distance longitudinally along the conductor from the first point in the direction away from the break to be detected;

transforming the transient changes of pressure detected at the first point into a first electrical signal proportional thereto;

transforming the transient changes of pressure detected at the second point into a second electrical signal proportional thereto;

delaying the second electrical signal for a preselected time duration substantially equal to the distance between the first and second points divided by the speed of sound in the gas;

comparing the delayed second electrical signal with the first electrical signal and producing a third electrical signal comprised of the difference between the first electrical signal and the delayed second electrical signal; and

actuating indicating means responsive to the third electrical signal to indicate the existence of the break which generates a compressional wave that passes the first point prior to passing the second point.

8. The method of rapidly detecting and indicating the existence of a rupture, break or other occurrence in a conductor containing gas under pressure, which rupture, break or other occurrence generates compressional waves through the gas contained in the conductor, wherein the rupture, break or other occurrence is detected at a first detection point longitudinally spaced in a preselected direction in the gas from the rupture, break or other occurrence, and wherein compressional waves traveling through the gas toward the first detection point from the opposite direction are not allowed to substantially interfere with the detection and indication, including the steps of:

detecting at the first detection point transient changes in the pressure of the gas and generating a first electrical signal proportional thereto;

detecting at a second detection point transient changes in the pressure of the gas and generating a second electrical signal responsive thereto, the second detection point being located a preselected distance longitudinally from the first point in the preselected direction;

delaying the second electrical signal for a time duration substantially equal to the preselected distance between the first and second detection points divided by the speed of sound in the gas;

comparing the first electrical signal and the delayed signal electrical signal and generating a third electrical signal proportional to the difference therebetween;

transforming the third electrical signal into a binary signal which is a preselected one of a first and second states whenever the absolute value of the third electrical signal exceeds a preselected threshold magnitude; and

actuating indicating means responsive to the binary signal being of the preselected one of the first and second states.

9. In a pressurized gas pipeline system having a length of pipeline connecting between first and second compression stations or the like, each of which causes transient changes in the pressure of the gas in the vicinity thereof, the method of rapidly detecting the existence and determining the location of a break or other occurrence in the pipeline between the first and second compression stations, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, wherein the transient changes in the pressure of the gas produced by the first and second compression stations are prevented from interfering substantially with detecting the break or other occurrence and determining its location, including the steps of:

detecting transient changes in the pressure of the gas at a first point in the gas in the vicinity of the first compression station and generating a first electrical signal proportional thereto;

detecting transient changes in the pressure of the gas at a second point in tHe gas in the vicinity of the second compression station and generating a second electrical signal proportional thereto;

detecting transient changes in the pressure of the gas at a third point in the gas a selected distance along the length of pipeline from the first point toward the first compression station and generating a third electrical signal proportional thereto;

detecting transient changes in the pressure of the gas at a fourth point in the gas a selected distance along the length of pipeline from the second point toward the second compression station and generating a fourth electrical signal proportional thereto;

delaying the third electrical signal a period of time substantially equal to the distance between the first and third points divided by the speed of sound in the gas;

delaying the fourth electrical signal a period of time substantially equal to the distance between the second and fourth points divided by the speed of sound in the gas;

comparing the first electrical signal and the delayed third electrical signal and producing a fifth electrical signal which is representative of at least the leading edge of the adiabatic pressure wave created in the gas by the break or other occurrence and propagated through the gas at the speed of sound;

comparing the second electrical and the delayed fourth electrical and producing the sixth electrical signal which is representative of at least the leading edge of the adiabatic pressure wave created in the gas by the break or other occurrence and propagated through the gas at the speed of sound;

monitoring the fifth electrical signal and determining the instant of time that the leading edge of the adiabatic pressure wave reached the first point in the gas;

monitoring the sixth electrical signal and determining the instant of time that the leading edge of the adiabatic pressure wave reached the second point in the gas; and

solving either of the following equations;

10. In a pressurized gas pipeline system having a plurality of individual piplesine interconnected together at a header or the like into a trunk pipeline, wherein the trunk pipeline extends from a compression station or the like which generates transient changes in the pressure of the gas in the vicinity of the compression station, the method of rapidly detecting the existence of a break or other occurrence occurring in one of the individual pipelines, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to progate through the gas at the speed of sound, including the steps of:

detecting changes in the pressure of the gas at a stationary point in each of the individual pipelines in the vicinity of the header and generating first electrical signal for each of the individual pipelines proportional to the detected changes in the pressure of the gas in the respective individual pipelines;

detecting changes in the pressure of the Gas at a stationary point in the trunk pipeline and generating a trunk electrical signal proportional thereto;

delaying the trunk electrical signal for a selected period or periods of time, the trunk electrical signal being delayed, for each of the first electrical signals, a time period substantially equal to the pipeline distance between the stationary point in the respective individual pipeline and the stationary point in the trunk pipeline divided by the speed of sound at the gas;

comparing each of the first electrical signals with the respective delayed trunk electrical signal;

producing from each comparison a third electrical signal which is respresentative of the difference between the first electrical signal and the delayed trunk electrical signal;

monitoring each of the third electrical signals to detect the portion of the signal representative of the leading edge of the adiabatic wave generated by the break or other occurrence in the particular individual pipeline and propagated through the gas at the speed of sound; and

responsive to the detection of a portion of the third electrical signals representative of the leading edge of the adiabatic pressure wave, activating means indicative of the existence of the break or other occurrence and the one of the individual pipelines in which the break or other occurrence occurred.

11. In a pipeline system including a plurality of pipelines containing gas under pressure and interconnected at a common point, the method of rapidly detecting in the vicinity of the common point, the existence of a distantly occurring break or other occurrence in one of the pipelines and of rapidly indicating in which one of the pipelines the break or other occurrence exists, which break or other occurrence produces a rapid and significant change in the pressure of the gas in the pipeline at the point of the break or other occurrence and causes a compressional wave to propagate at the speed of sound through the gas, including the steps of:

detecting changes in the pressure of the gas at a monitioring point in the gas in each of the plurality of interconnected conductors, each of the monitoring points being located in the respective conductor a known equal distance from the center of the interconnection of the plurality of conductors, the distance being measured along the center of the conductors;

transforming the pressure changes detected at each of the monitoring points into first plurality of electrical signals responsive thereto;

comparing the first plurality of electrical signals to produce a second plurality of electrical signals, each of which is responsive to one of the first plurality of electrical signals and is comprised of only those portions of the one of the first plurality of electrical signals to which it is responsive that are not common all of the first plurality of electrical signals;

comparing the second plurality of electrical signals to detect which one of the signals was first produced; and

actuating indicating means responsive to the one of the second plurality of electrical signals first produced to indicate both the existence of the break or other occurrence generating the compressional wave and the particular conductor in which the break or other occurrence exists.

12. The method according to claim 11, including the additional steps of:

producing a first plurality of logical voltage signals indicative of which one of the second plurality of electrical signals was first produced;

comparing the second plurality of electrical signals to detect which one of the signals produced during a preselected time duration had the greatest positive amplitude, and producing a second plurality of logical voltage signals indicative of which one of the second plurality of electrical signals had the greatest positive amplitude during the preselected time duration;

comparing the first and second plurality of logical signals to detect correlation therebetween; and

actuating indicating means responsive to the correlation if any betweem the first and second logical voltage signals to indicate both the existence of the break or other occurrence generating the compression wave and the particular conductor in which the break or other occurrence exists.

13. The method according to claim 11, including the additional steps of:

summing and amplifying the first plurality of electrical signals to produce a summed and amplified electrical signal;

differentiating with respect to time the summed and amplified electrical signal to produce a differentiated electrical signal;

comparing the differentiated electrical signal to zero voltage to determine whether the change in voltage if any with respect to time increasing or decreasing, and producing a compared electrical signal responsive thereto; and

actuating indicating means responsive to the compared electrical signal.

14. In a pipeline containing gas under pressure, an apparatus for rapidly detecting at a selected stationary monitoring point the existence of a break or other occurrence occurring distantly in the pipeline, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, comprising:

pressure/electrical transducer means connected to the pipeline and in communication with the gas at the monitoring point for continuously transducing transient changes of the pressure of the gas into a first electrical signal proportional thereto;

means coupled to the output of the transducer means for continuously monitoring the first electrical signal to detect a portion thereof representative of at least the leading edge of the adiabatic pressure wave created in the gas by the break or other occurrence and propagated through the gas and for generating a second electrical signal indicative thereof; and

means coupled to the output of the monitoring means for indicating, responsive to the second electrical signal, the existence of the break or other occurrence.

15. In a pipeline containing gas under pressure, an apparatus for rapidly detecting at a selected stationary monitoring point the existence of a break or other occurrence occurring distantly in the pipeline, according to claim 14, and for rapidly determining the distance between the break or other occurrence and the monitoring point in the gas, wherein the means for continuously monitoring the first electrical signal includes:

means for determining from the first electrical signal the rate of change in the pressure of the gas as the pressure of the gas changed adiabatically during a portion of the time that the leading edge of the adiabatic pressure wave was passing the monitoring point; and

means coupled to the output of the determining means for solving the following equation;

16. In a length of pipeline containing gas under pressure and extending from a compression station or the like which causes transient changes in the pressure of the gas at a selected stationary first monitoring point in the length of pipeline, an apparatus for rapidly detecting at the first monitoring point a break or other occurrence distantly occurring in the pipeline on the opposite side of the first monitoring point from the compression station, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, comprising:

means for detecting transient changes in the pressure of the gas at the first monitoring point in the gas and for generating a first electrical signal proportion thereto;

means for detecting transient changes in the pressure of the gas at a second stationary monitoring point in the gas selected distance along the pipeline from the first point toward the compression station and for generating a second electrical signal proportional thereto;

means coupled to the output of the second detecting and generating means for delaying the second electrical signal for a period of time substantially equal to the distance along the pipeline between the first and second points divided by the speed of sound in the gas;

means coupled to the output of the delay means and the first detecting and generating means for comparing the first electrical signal and the delayed second electrical signal and for producing a third electrical signal proportional to the difference therebetween, which third electrical signal is representative of at least the leading edge of the adiabatic pressure wave generated in the gas by the break or other occurrence and propagated through the gas at the speed of sound;

means coupled to the output of the comparing means for monitoring the third electrical signal and for detecting the portion thereof representative of the leading edge of the adiabatic pressure wave generated in the gas by the break or other occurrence and propagated through the gas at the speed of sound; and

means coupled to the output of the monitoring means for indicating the existence of the break or other occurrence.

17. In a pipeline containing gas under pressure and extending from a compression station or the like which causes transient changes in the pressure of the gas at a selected stationary first monitoring point in the length of pipeline, an apparatus for rapidly detecting at the first monitoring point a break or other occurrence distantly occurring in the pipeline on the opposite side of the first monitoring point from the compression station, which break or other occurrences produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, according to claim 16, and for determining the distance between the break or other occurrence and the first monitoring point, including:

means coupled to the output of the comparing means for determining from the third electrical signal, the change in the pressure of the gas with respect to time during at least a portion of the time the pressure of the gas changed adiabatically responsive to the leading edge of the adiabatic pressure waves passing the first monitoring point; and

means coupled to the output of the determining means for solving the following equation;

18. An apparatus for rapidly detecting and indicating the existence of a break or other occurrence in a gas conductor containing gas under pressure, which break or other occurrence occurs in the gas conductor somewhere along the conductor in a selected direction from a reference position and which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes a compressional wave to be propagated at the speed of sound through the gas contained in the conductor, comprising:

a first pressure/electrical transducer for detecting transient changes in the pressure of the gas and generating an electrical signal proportional thereto, the first transducer being in communication with the gas at a first point located at the reference position;

a second pressure/electrical transducer for detecting transient changes in the pressure of the gas at a second point in the gas and for generating a second electrical signal proportional thereto, the second point being located in the gas a known distance along the pipeline from the first point on the opposite side of the reference position from the break or other occurrence to be detected;

means coupled to the output of the second transducer for delaying the second electrical signal for a preselected time duration substantially equal to the distance between the first and second points divided by the speed of sound in the gas;

means coupled to the output of the first transducer and the delay means for comparing the delayed second electrical signal and the first electrical signal and for producing a third electrical signal comprising the difference between the first electrical and the delayed second electrical signal; and

means coupled to the output of the comparing means for indicating, responsive to the third electrical signal, the existence of the break or other occurrence which generates a compressional wave that passes the first point prior to passing the second point.

19. An apparatus according to claim 18, comprising:

means for differentiating with respect to time the third electrical signal to produce a differentiated electrical signal;

means for comparing the differentiated electrical signal to zero voltage to detect whether the change of voltage if any with respect to time is increasing or decreasing and to produce a compared electrical signal; and

means responsive to the compared electrical signal to indicate whether the pressure is increasing or decreasing.

20. An apparatus for rapidly detecting and indicating the existence of a rupture, break or other condition in a gas conductor, which rupture, break or other condition generates compressional waves through the gas contained in the conductor, wherein the rupture, break or other occurrence is detected at a first detection point longitudinally spaced in a preselected direction in the gas from the rupture, break or other condition and wherein compressional waves traveling through the gas toward the first detection point from the opposite direction are prevented from substantially interfering with the detection and indication, coMprising:

means positioned in the gas at the first detection point for detecting transient changes in the pressure of the gas and for generating a first electrical signal proportional thereto;

means positioned at a second detection point in the gas for detecting transient changes in the pressure of the gas and for generating a second electrical signal responsive thereto, the second detection point being located at a preselected distance longitudinally from the first point in the preselected direction;

the first electrical signal and the second electrical signal each having a preselected one of its parameters of voltage and current proportional in magnitude to the change in the pressure of the gas at the first and second detection points, respectively;

means for delaying the second electrical signal for a time duration substantially equal to the preselected distance between the first and second detection points divided by the speed of sound in the gas;

means for comparing the first electrical signal and the delayed second electrical signal and for generating a third electrical signal proportional to the differnce therebetween, the comparing means including;

means for comparing the magnitudes of the first and second electrical signals to determine the difference therebetween, and means for generating a third electrical signal having a preselected one of its parameters of voltage and current proportional in magnitude to such differences; and

means connected to the output of the comparing means for indicating responsive to the third electrical signal the existence of the rupture, break or other condition, the indicating means including;

means for transforming the third electrical signal into a binary signal, and means responsive to a preselected one of the first and second states of the binary signal for indicating the existence of the rupture, break or other condition.

21. In a pressurized gas pipeline system having a length of pipeline connected between first and second compression stations or the like, each of which causes transient changes in the pressure of the gas in the vicinity thereof, an apparatus for rapidly detecting a break or other occurrence occuring in the length of pipeline somewhere between the first and second compression stations and for rapidly determining the location of the break or other occurrence along the length of pipeline between the first and second compression stations, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, comprising:

a first pressure/electrical transducer for detecting transient changes in the pressure of the gas at a first point in the gas in the length of pipeline in the vicinity of the first compression station and for generating a first electrical signal proportional thereto;

a second pressure/electrical transducer for detecting transient changes in the pressure of the gas at a second point in the gas in the length of pipeline in the vicinity of the second compression station and for generating a second electrical signal proportional thereto;

a third pressure/electrical transducer for detecting transient changes in the pressure of the gas at a third point in the gas in the length of pipeline a selected distance along the length of pipeline from the first point toward the first compression station and for generating a third electrical signal proportional thereto;

a fourth pressure/electrical transducer for detecting transient changes in the pressure of the gas at a fourth point in the gas in the length of pipeline a selected distance along the length of pipeline from the second point toward the second compression station and for generating a fourth electrical signal proportional thereto;

first delay means coupled to the output of the third transducer for delaying the third Electrical signal a period of time substantially equal to the distance between the first and third points divided by the speed of sound in the gas;

second delay means coupled to the output of the fourth transducer for delaying the fourth electrical signal a period of time substantially equal to the distance between the second and fourth points divided by the speed of sound in the gas;

first comparing means coupled to the outputs of the first transducer and the first delay means for comparing the first electrical signal and the delayed third electrical and for producing a fifth electrical signal which is representative of at least the leading edge of the adiabatic pressure wave generated in the gas by the break or other occurrence and propagated through the gas at the speed of sound;

second comparing means coupled to the outputs of the second transducer and the second delay means for comparing the second electrical signal and the delayed fourth electrical signal and for producing a sixth electrical signal which is representative of at least the leading edge of the adiabatic pressure wave generated in the gas by the break or other occurrence and propagated through the gas at the speed of sound;

means coupled to the output of the first comparing means for monitoring the fifth electrical signal and for determining the instant of time that the leading edge of the adiabatic pressure wave reaches the first point in the gas;

means coupled to the output of the second comparing means for monitoring the sixth electrical signal and for determining the instant of time that the leading edge of the adiabatic pressure wave reaches the second point in the gas; and

means for solving either of the following equations;

22. In a pressurized gas pipeline system having a plurality of individual pipelines interconnected together at a header or the like into a trunk pipeline, wherein the trunk pipeline extends from a compression station or the like which generates transient changes in the pressure of the gas in the vicinity of the header, an apparatus for rapidly detecting in the vicinity of the header the existence of a break or other occurrence occurring in one of the individual pipelines, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes an adiabatic pressure wave to propagate through the gas at the speed of sound, comprising:

a first pressure/electrical transducer in communication with the gas at a stationary monitoring point in each of the individual pipelines in the vicinity of the header for detecting transient changes in the pressure of the gas and generating a first electrical signal proportional thereto for each of the individual pipelines;

a trunk pressure/electrical transducer in communication with the gas at a stationary monitoring point in the trunk pipeline for detecting transient changes in the pressure of the gas and generating a trunk electrical signal proportional thereto;

meanS coupled to the output of the trunk transducer for delaying the trunk electrical signal for a selected period or periods of time, the trunk electrical signal being delayed for each of the first electrical signals a time period substantially equal to the distance between the respective stationary monitoring point in the individual pipeline and the stationary monitoring point in the trunk pipeline divided by the speed of sound in the gas;

a comparing means for each of the first transducers coupled to the output of the delaying means and to a respective one of the first transducers for comparing the respective first electrical signal and the respective delayed trunk signal and generating a compared electrical signal proportional to the difference therebetween; and

means coupled to the output of each of the comparing means for monitoring each of the compared electrical signals and for detecting the portion of any such compared electrical signal representative of the compressional wave created in the gas in one of the pipelines by the break in such pipeline and propagated through such gas toward the header; and

means coupled to the output of the monitoring means for indicating the existence of the break and the particular pipeline in which the break occurred.

23. In a pipeline system including a plurality of pipelines interconnected at a common point and containing gas under pressure, an apparatus for rapidly detecting in the vicinity of the common point the existence of a distantly occurring break or other occurrence in one of the pipelines and for indicating in which one of the pipelines the break or other occurrence occurred, which break or other occurrence produces a rapid and significant change in the pressure of the gas at the point of the break or other occurrence and causes a compressional wave to propagate at the speed of sound through the gas, comprising:

transducer means positioned at a monitoring point in each of the plurality of pipelines in the vicinity of the interconnecting common point for monitoring transient changes in the pressure of the gas and for transducing such transient changes in the pressure into a proportional electrical signal, the outputs the transducer means providing a first plurality of electrical signals, each of the transducer means being located in its respective pipeline a known equal distance from the center of the interconnection of the plurality of pipelines, the distance being measured along the center of said pipelines;

means for comparing each of the first plurality of electrical signals with each other of the first plurality of electrical signals to produce a second plurality of electrical signals, each of which is responsive to one of the first plurality of electrical signals and is comprised of those portions of the one of the first plurality of electrical signals to which it is responsive that are not common to all of the first plurality of electrical signals;

means for comparing the second plurality of electrical signals to detect which one of the signals was first produced; and

means for actuating indicating means responsive to the one of the second plurality of electrical signals first produced indicating both the existence of the break or other occurrence generating a compressional wave and the particular pipeline in which the break or other occurrence exists.