Annals of Occupational Hygiene Advance Access originally published online on July 20, 2006
Annals of Occupational Hygiene 2007 51(1):35-43; doi:10.1093/annhyg/mel049
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Local Ventilation Solution for Large, Warm Emission Sources
1 VTT Industrial Systems P.O. Box 13001, FIN-33101 Tampere, Finland
2 Finnish Institute of Occupational Health Laserkatu 6, FIN-53850 Lappeenranta, Finland
*Author to whom correspondence should be addressed. Tel: +358 304 743201; fax: +358 304 743230; e-mail: irma.welling{at}ttl.fi
In a foundry casting line, contaminants are released from a large area. Casting fumes include both volatile and particulate compounds. The volatile fraction contains hydrocarbons, whereas the particulate fraction mostly comprises a mixture of vaporized metal fumes. Casting fumes lower the air quality in foundries. The design of local ventilation for the casting area is a challenging task, because of the large casting area and convection plumes from warm moulds. A local ventilation solution for the mould casting area was designed and dimensioned with the aid of computational fluid dynamic (CFD) calculations. According to the calculations, the most efficient solution was a pushpull ventilation system. The prototype of the pushpull system was built and tested in actual operation at the foundry. The push flow was generated by a free plane jet that blew across the 10 m wide casting area towards an exhaust hood on the opposite side of the casting lines. The capture efficiency of the prototype was determined by the tracer gas method. The measured capture efficiencies with push jet varied between 40 and 80%, depending on the distance between the source and the exhaust. With the aid of the push flow, the average capture efficiency was increased from 40 (without jet) to 60%.
Keywords: CFD push-pull ventilation casting local exhaust ventilation