Q45S Wet H2S Gas Detector

ATi’s Q45S Wet H2S Gas Detector offers continuous monitoring of Hydrogen Sulfide in both inlet and discharge air, where condensing humidity conditions are normal.

Continuous, reliable H2S monitoring in wet conditions

Odour control in wastewater treatment plants and sewage collection systems often requires the use of scrubber systems. Many of these scrubbers employ a wet process using a hypochlorite solution to remove hydrogen sulfide (H2S) from air streams prior to discharge. Monitoring the hydrogen sulfide in both inlet and discharge air has presented problems for standard sulfide gas sensors. 

ATi’s Q45S Wet H2S gas monitor is a new type of gas sensor technology that allows continuous monitoring of hydrogen sulfide in both inlet and discharge air, where condensing humidity conditions are normal.

Measurements may be either at the inlet to scrubber systems where gas concentrations can run as high as 200 PPM or at the outlet, where gas concentrations are ideally down below 0.5 PPM. Special gas sensor configurations are available for either duct insertion or flowcell use. As Q45S Wet H2S Gas Detector systems are often monitoring gas streams with condensing levels of water vapor, provision has been made for eliminating water droplets from the gas sensor that could present a barrier to the diffusion of hydrogen sulfide into the sensor. An optional air-purge system controlled by the gas transmitter will periodically deliver a blast of air across the critical sensor surfaces to remove water droplets. This system insures a clear gas diffusion path to the sensor and reliable measurements on a continuous basis.

Features & specification

  • Special Wet H2S Sensors designed to operate in condensing gas streams
  • Automatic Sensor Air Purge
  • Two Internal Alarm Relays
  • LCD Display
  • Internal Data Logger that stores up to 10 days of data at 1 minute storage intervals
  • Output Simulation
  • Weather-proof Nema 4X Enclosure


  • Water Treatment
  • Wastewater Treatment



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