Automated Listening for Gas Leaks

In facilities handling hydrocarbons from upstream oil and gas production through midstream and downstream processing and storage facilities, gas leaks are a concern.

Emerson's Eliot Sizeland

Eliot Sizeland
Head of Sales & Marketing, Gas Leak Detection

Ultrasonic-Gas-Leak-DetectionIn a World Oil article, Ultrasonic devices improve gas leak detection in challenging environments, Emerson’s Eliot Sizeland describes how ultrasonic technology can provide efficient and effective coverage on top of existing gas detection systems or in challenging applications where gas accumulations do not occur.

Many types of gas leaks can occur:

…hydrocarbon, hydrogen, hydrogen sulfide (H2S) and more. Each type of leak is accompanied by its own safety concerns for plant, personnel or both.

Traditional gas detectors work well for enclosed areas where gases accumulate. Technologies include:

…infrared, catalytic bead and electrochemical-based sensors…

In open or well-ventilated areas the gases may not accumulate, but the:

…danger remains, however, that conditions can change dramatically, extending the area in which LEL (lower explosive limit) and even ppm (parts per million) levels are factors, with gases often building to dangerous concentrations far from the leak source.

The idea behind ultrasonic gas leak detectors (USGDs) is to listen for noise generated by gas leaks which occur in the ultrasonic frequency range (>25MHz). It is a technology:

…that uses acoustic sensors to detect changes in noise within an environment that is outside the scope of human hearing… This detector “hears” the leak, rather than measuring the accumulated gas.

This technology has application in offshore oil & gas platforms and onshore well pads, refineries, gas storage facilities, and liquefied natural gas (LNG) plants to name a few.

Eliot shares a gas wellhead example. Concerns with traditional gas detectors was placement and:

…how difficult it would be for operators to access the area for maintenance and repair… The second concern was the unlikely potential for a gas cloud to accumulate, close to the leak location.

These leak detectors require tuning to understand ambient noises in the ultrasonic frequency range as well as intermittent noises and noise time durations from process equipment such as pressure relief valves, turbine compressors, etc. Eliot shares example settings for gas leak detection in high-, low-, and very low-noise environments.

He concludes:

No single leak detection method is appropriate for all applications—there is no perfect solution. In many confined areas, a standard point monitoring device for LEL measurement of gas concentration is still the right detector for the job.

The [USGD] detectors are extremely robust and reliable. They provide an almost instantaneous response-and-deliver coverage area in even the most challenging environments. And depending on the acoustic sensor employed, they will never require calibration and the sensor, itself, will never expire. That means there is virtually zero maintenance fir the life of the instrument.

Read the article for more on leak rate importance and detection coverage setup and examples.

You can also connect and interact with other gas detector and analyzer experts in the Analyzer group in the Emerson Exchange 365 community.

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