A fixed gas detector is permanently installed to provide continuous monitoring of plant and equipment emissions and ensure the safety of personnel along with assets. Preemptively warning of flammable, toxic gas and vapour release or Oxygen depletion. Detectors can be installed indoors or outside. Typically equipped with sensors, although some monitors use ultrasonic acoustic microphones for leakage detection, as they are unaffected by wind and weather.

Calibration times vary dependent on sensors, expired time and usage. For the gas detector pictured left (standard 4 gas monitor LEL, CO, H2S, O2), the recommended calibration period is every six months.