Characterising the smoke produced from modern materials and evaluating smoke detectors

The purpose of this research project was to measure the smoke characteristics for a number of test fires in smouldering and flaming modes and compare them with the existing four test fires specified in EN 54-7 and EN 14604 currently used to assess smoke detectors.

This was to investigate whether the four test fires adequately represent a broad range of smoke types that can be expected in commercial and domestic environments today. It was also an opportunity to also assess the performance of twelve approved ionisation and optical smoke detectors to the smoke produced from these alternative materials.

Twenty-nine test fires were conducted including those in EN 54-7 and EN 14604 and of these 24 were considered to be complete tests generating sufficient smoke for detectors to respond. Of these sixteen were found to be within the smouldering to flaming range bounded by the TF2 and TF5 test fires (from EN 54-7 and EN 14604) and four smouldering and four flaming fires were found to be beyond the limits (m/y) for the limiting TF2 and TF5 fires respectively.

Twelve different approved smoke detectors were installed on the ceiling and the wall and then exposed to the smoke from the test fires. For all the complete fires there were 6 no responses and 270 responses which represents a 97.8% pass rate. The detectors responsible for the 6 no responses were investigated further and reasons for their lack of response were proposed.

It is evident that commercial and domestic types whether they are ionisation or optical detectors respond to a broad range of fires outside and inside the limits of the test fires in EN 54-7 and EN 14604. It was confirmed that both ionisation or optical smoke detectors are attuned to detecting certain types of fires and in order to ensure that the most appropriate type of device is installed guidance on the appropriate use of ion and optical smoke detectors should be sought from BS 5839-1:2013.