Analytical Technology (ATi) has developed an innovative new odour monitoring system for continuous, reliable monitoring of H2S (hydrogen sulphide) 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 hypochlorite solution to remove H2S from air streams prior to discharge.
Monitoring H2S in both inlet and discharge air presents problems for conventional sulphide gas sensors.
Water droplets can often occur when monitoring gas streams with condensing levels of water vapour, presenting barriers to the diffusion of H2S into the sensors.
The key advantage of the new Q45S is that it utilises a special wet H2S sensor that eliminates water vapour bleeding for accurate and cost-effective H2S monitoring, where condensing humidity conditions are normal.
The novel Q45S combines Ati's CSA/UL certified Q45 electronics package and the special wet H2S sensor on a single platform.
Wet H2S is a direct insertion sensor, meaning that no sampling is required.
A flexible monitoring capability allows measurements to be made either at the inlet to scrubber systems, where concentrations can run as high as 200ppm, or at the outlet, where concentrations are ideally below 0.5ppm.
Special sensor configurations are also available for either duct insertion or flowcell use.
An optional automatic air-purge system controlled by the transmitter periodically delivers a blast of air across the critical sensor surfaces to remove accumulated water droplets.
This ensures a clear gas diffusion path to the sensor, long-term operation and reliable measurements without loss of sulphides.
The Q45S has been equipped with an LCD monitor ensuring that H2S concentration is displayed in large, easy to read figures while a secondary information line indicates other status data such as raw sensor output and mA output.
The display has been designed to be easily programmed using only four keys located on the front panel.
Furthermore, the Q45S features two internal alarm relays.
One relay is used to control the air purge system and the other is available for external alarm functions.
Both relays are programmable for setpoint, hysteresis and delay functions.
The transmitter analog output can be set to user definable values and relay outputs can be set to specific states for complete simulation of detection system operation.
Output and alarms may also be inhibited for maintenance and calibration.
Additionally, the new Q45S is housed in a weatherproof Nema 4X enclosure.
For temporary installations, a special battery-powered version of the Q45S is also available.
The system runs on an internal 9volt battery and contains a data-logger for storing information at one-minute intervals on existing air collection systems.
Depending on the specific application needs, a standard 9volt battery ensures that the unit operates for four days while a 9volt lithium battery provides about ten days of operation.
Data are easily downloaded to any PC using the software supplied as standard with the unit.
