Backgroundnoise

Before setting up the trigger level and installing the acoustic gas leak detection system, it is important that the background noise is estimated or measured onsite. This eliminates the risk that the background noise will give false alarms.

It should be noted that most noise sources (machines, generators, turbines) generate sound below the detectable frequency range of the Gassonic acoustic gas detectors. Below, examples of typical ultrasonic background noise levels.

Onshore wellhead area (<58 dB)
Normal plant processing area, no compressors in close vicinity (<68 dB)
Offshore open bridge area, in strong winds of 15-20 m/s (<78 dB)
Compressor area or area with other rotating machinery or turbines (<78 dB)

These noise levels are used to decide the alarm trigger level and detection coverage for ultrasonic gas detectors.

Avoidingfalsealarms

Even though most noise is below the detection frequency of the ultrasonic detectors, spontaneous air releases from certain industrial sources could trigger the ultrasonic (acoustic) gas leak detectors. Therefore, the Gassonic detectors have a built-in delay function to prevent spurious alarms from occurring. Alternatively, the trigger level and the alarm relay can be integrated into the plant DCS system through the 4-20 mA signal of the Gassonic Observer.