The Evaluation of Bitumen Fume Capture Efficiency for Road Pavers

INRS has evaluated the performance of fume extraction systems on road pavement asphalt pavers over a two year period between 2009 and 2011. These systems are used to reduce operator exposure by capturing fumes at the auger, where most emissions are generated, and discharging them above the paver at sufficient velocity to prevent fumes blowing back towards the operator cab. Evaluation was conducted using a tracer gas (SF6), based on the NIOSH-proposed protocol (1997). Initial tests revealed the limits of this methodology, which included adverse effects on measurement resulting from the paver being located in a test hall; panelling installed to isolate the machine from draughts seriously distorted the flow field. Further tracer gas tests conducted outside, under conditions more representative of real operation, showed that the fume capture system must be integrated into the machine design. Special attention should be given when implementing various cooling systems (diesel engine, hydraulic compressor) since air draughts from these, if improperly directed, may greatly degrade fume capture efficiency.