Gas line leak evacuation and monitoring system

Abstract

An apparatus and method for evacuating gas from the soil surrounding a leaking gas conduit utilizes non-sparking and static dissipating components to reduce the risk of an explosion. The evacuation of gas from probes in boreholes in the vicinity of the leak is induced solely by a downstream blower where air is mixed with the gas and the gas / air mixture monitored to maintain the gas concentration below potentially explosive levels.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to an apparatus and method for rapidly and accurately pinpointing the location of an underground leak in a gas line in a manner that greatly reduces the risks of explosion. [0002] Determining the location of a leak in an underground gas line has long posed difficult problems for gas line emergency repair crews. Although the leaking gas line itself is easily located, the permeation of the soil or other overlayer with gas from the leak makes it difficult to pinpoint the actual location of the leak. As a result, it has not been uncommon for large stretches of a surface, including paved roadways, to have to be excavated in a somewhat random fashion to locate the actual site of the leak. This, of course, is costly and time-consuming. In addition, the continuous leaking gas creates a greater hazard the longer the leak continues. [0003] It is known in the prior art to use a so-called “bar hole purger” to remove gas from a sma...

AI Technical Summary

Benefits of technology

[0007] The apparatus of the present invention is used to evacuate gas from soil or other porous overlayer surrounding a leaking gas conduit to assist in locating the leak and to minimize the risk of igniting an explosive gas / air mixture. The apparatus includes a plurality of gas probes, each of which is adapted to be operatively connected to a borehole in the soil, each probe having an inlet for admission of gas from the soil. A common header and flexible lines interconnect the probes and include a connection at a downstream end to a vacuum source to draw gas from the soil surrounding the boreholes. Demountable fittings and connectors are provided for interconnecting the header and lines with the probes and the vacuum source. The probes, fittings and connectors are made of non-sparking materials. The lines, which are preferably flexible, have a static dissipating construction.

[0012] Also in accordance with the present invention, a method is disclosed for evacuating gas from soil or other porous overlayer surrounding a leaking gas conduit to assist in locating the leak and minimizing the risk of igniting an explosive gas / air mixture. The method preferably includes the steps of (1) forming a plurality of boreholes in the overlayer in the proximity of the leak, (2) inserting probes having gas inlets into the boreholes, (3) connecting the probes to a common header, (4) drawing a vacuum on the downstream end of the header to draw gas from the probes in the boreholes, (5) simultaneously using the vacuum to draw ambient air and mixing the air with the gas, (6) monitoring the concentration of gas in the gas / air mixture, (7) discontinuing the vacuum when the gas concentration approaches 0, (8) testing the boreholes for the return presence of gas, (9) using the timing of the return presence of gas to more accurately determine the location of the leak, and (10) repeating steps (2)-(9).

Problems solved by technology

Determining the location of a leak in an underground gas line has long posed difficult problems for gas line emergency repair crews.

Although the leaking gas line itself is easily located, the permeation of the soil or other overlayer with gas from the leak makes it difficult to pinpoint the actual location of the leak.

This, of course, is costly and time-consuming.

In addition, the continuous leaking gas creates a greater hazard the longer the leak continues.

This system is slow and costly, in terms of the amount of machinery required to locate the leak.

In addition, the system has no safeguards to protect against a possible ignition of an explosive gas / air mixture.

The above described system suffers from a number of deficiencies.

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