Gas detection in ambient air is extremely important in a wide range of industrial and commercial sectors: for example as warning of the presence of inflammable or explosive gases, such as acetylene, propane, butane etc, CO2 regulation in rooms, or the measurement of methane concentration in bio-gas plants. Often the systems used for such applications suffer numerous drawbacks concerning the quality and reliability of detection and measurement, with such devices requiring frequent maintenance or even replacement.
Simply put, infra-red detection and measurement systems are a significantly better alternative. The method is based on the property of gases to absorb infrared radiation at a specific wavelength. This property is characteristic for each gas, meaning sensors can be very sensitive and virtually free of any cross-interference. With its smartMODUL sensor, smartGAS Mikrosensorik GmbH (Germany) offer such a system, which the manufacturers claim has a working life of at least ten years. A helical filament provides a broadband infrared source and a filter selects the specific wavelength. The sensor is no larger than a matchbox and can be integrated into new as well as existing systems.
In the past, device interfaces were manufacturer-specific, but today smartGAS offers all conventional types of interface, such as linear analogue outputs (e.g. 4 – 20 mA, Â 0-1 V) or a RS485 interface etc. An external watchdog monitors the sensory system. This function is particularly useful for applications in process industries. Possible power supplies range from DC 12 V – 30 V.
Although in the standard version gas diffuses across the sensor, a through-flow version is also possible, in that the sensor is contained within a housing equipped with an inlet and outlet, allowing the device to be perfused. The smartMODUL is available for the following gases: acetylene, butane, ethane, ethylene, carbon dioxide, carbon monoxide, methane, propane and sulphur hexafluoride. Versions for other gases are possible on request.
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