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Odor 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 hypochlorite solution to remove 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 has developed sensor technology that now allows continuous monitoring in this type of application, where condensing humidity conditions are normal.

Designated Model Q45S, the odor monitoring system uses our standard Q45 electronics package in conjunction with a special “Wet H2S” sensor. Measurements may be made either at the inlet to scrubber systems where concentrations can run as high as 200 PPM, or at the outlet where concentrations are ideally down below 0.5 PPM. Special sensor configurations are available for either duct insertion or flowcell use.

Because Q45S systems are often monitoring gas streams with condensing levels of water vapor, provision has been made for eliminating water droplets from the sensor that could present a barrier to the diffusion of H2S into the sensor. An optional air-purge system controlled by the transmitter will periodically deliver a blast of air across the crititcal sensor surfaces to remove water droplets.  This system insures a clear gas diffusion path to the sensor and reliable measurements on a continuous basis.

Q45S transmitters provide a large, easy to read LCD display of H2S concentration with a second display line to indicate other status information. An alarm contact is available for external alarming functions, and a second contact may be used for alarm purposes if the air purge system is not implemented in a given application. An isolated 4-20 mA output is provided for remote data transmission, and output spans are user programmable for ranges of 0-2.000 PPM up to 0-200.0 PPM.

A special battery-powered version of the Q45S is available for use in temporary installations. This system runs on an internal 9 volt battery and contains a data-logger for collecting information on existing air collection systems. A standard 9 volt battery will operate the unit for 4 days, while a 9 volt lithium battery will provide about 10 days of operation. Data is easily downloaded to a standard PC using software supplied with the unit.