Before setting up the trigger level and installing the ultrasonic (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 detectors. Underneath, examples of typical ultrasonic background noise levels.

• Onshore wellhead area (<58-64 dB)
• Offshore open bridge area, in strong winds of 15-20 m/s (<58–64 dB)
• Normal plant processing area, no compressors in close vicinity (<58-64 dB)
• Compressor area or area with other rotating machinery or turbines (64-74 dB)

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.