Real-time monitoring of agricultural ammonia emissions based on optical fibre sensing technology

An optical fibre sensor system, capable of monitoring ammonia gas in real-time is described and its suitability for monitoring ambient levels, as low as 1ppm, within confined areas, e.g. livestock sheds, is presented. Unlike other optical sensors, which monitor in the infra-red region, this optical fibre sensor is based on monitoring absorption due to ammonia in the ultraviolet region. By monitoring in the UV region it is possible to overcome many of the cross-sensitivity issues previously associated with ammonia sensing, such as cross-sensitivity with atmospheric gases carbon dioxide and oxygen and also humidity. The sensor exhibits a fast response time (1s) to a wide range of ammonia gas concentrations (1 - 50ppm).