The Gassonic Observer ultrasonic gas detector from General Monitors, Lake Forest, CA, is designed to detect fugitive gas leaks in compressor stations. The device uses robust microphone technology to detect the airborne ultrasound generated from gas releases in open, well-ventilated areas. Detection radius is 20 m at a leak rate of 0.1 kg/s. The device also features an integrated acoustic self-test and a high-pass filter to remove frequencies <25 kHz, eliminating interference from audible and low-frequency ultrasonic noise. You can also set the alarm trigger level above that of the ultrasonic background noise to ensure immunity to other noise sources. The detector carries CSA, FM, ATEX, IECEx, and C-UL approvals.