Field: Built environment assessing and monitoring, Cultural heritage conservation
Global Technical function: Drying, Sensing
Technical Function Unit: Automatized and remote sensing, Identifying, In situ physical sensing, Tracking
Geographic Area: Sweden

SENSORGAN

Based on the need to find measures to protect historical organs, the SENSORGAN project (Sensor system for detection of harmful environments for pipe organs) has developed an automatized and remote sensing system. Church organs are large and complex pieces containing several different types of materials. Various types of wood, leather, brass, iron and pipe metals put together a sensitive combination when it comes to changes in the indoor environment. Each of the organ parts responds differently to a change in the indoor climate of the church and under certain microclimatic conditions, the organ parts will be harmed and it might be unplayable.

The project was supported by the European Commission under the Sixth Framework Programme (FP6), a grant funding programme, and based on the gathered expertise from six research units and a cultural centre. The mix of technical, chemical and cultural knowledge from Italy, Poland, Great Britain, Sweden and Brazil managed to give the so-developed sensing system all the appropriate features for measuring microclimatic changes relevant to church organs as well as a large potential for applications in other areas.

Through previous research projects, three essential components of indoor climate have been noted to be especially harmful to the organ: The presence of organic acids, variations of temperature and relative humidity and dew formation.  Organic acids, in particular acetic acid, are naturally released from the wooden parts of the organ and when entering the pipes, a corrosive environment is emerged. Fluctuating temperature and relative humidity is speeding up the corrosion process, and is also damaging to the wooden parts of the organ as drying the wood can lead to crack formation. Dew formation, leading to pipe condensation, is also affected by these critical parameters. Thus, variations of temperature, relative humidity and formation of condensation are critical processes to the organs.

The system is a built environment assessing and monitoring tool containing three different types of sensors for real-time measuring of environmental circumstances, identifying threats to the organ with regard to the above-mentioned processes. It contains a dosimeter, tracking organic acids to prevent corrosion to occur in the organ pipes. To avoid damages to the wooden parts, an acoustic emission sensor is indicating the fluctuations of humidity of the ambient air. To measure condensation, advanced technology is essential as the sensor has to be small, water-proof, and resistant to acidic environments and be operable in temperatures below zero. To meet the demands, an optical fibre sensor for detecting condensation and frost in or outside the pipes has been developed.

This in situ physical sensing system, where data is collected without disturbing the playing or the sound of the organ, was tested in several organs including a historical 17th- century organ in Poland. The technology readiness level of the sensor system is thereby ranked on the TRL scale. During the three-year project that ended in 2008, the acoustic emission sensor was commercialised by the British company Hanwell, but the other two sensors are still at prototype stage.

The so-developed system could be used for other applications within the field of cultural heritage conservation or in other areas. There is also a potential for individual development of the two sensors that have not yet been commercialised.