Case Study

Heat weld fume extraction solution for large Midlands based manufacturer

In June 2007 AES were approached by a large Midlands based manufacturer of earth moving and site access equipment, and requested to submit proposals for the provision of weld fume extraction for a planned manufacturing cell. As the manufacturing cell was to be located within an existing open plan work area 100% of the weld fume generated was required to be collected with no possibility of fume leaking into the adjacent work areas. Due to the planned production rates high usage of the welding bays was anticipated requiring storage locations adjacent to main welding bays where fabricated sub-assemblies would be allowed to cool. Whilst in these areas a large quantity heat fume would continue to be released. AES’s design solution was to provide 3 mtr x 3 mtr collection hood canopies for each of the three planned welding cells located at a height of 3 mtrs on supporting steel work. Connected to each of the main welding cell canopies was an additional 2mtr x 2.5 mtr satellite hood canopy located at a height of 2.5mtrs to provide fume extraction for the sub- assembly cooling areas. To provide effective extraction of weld fume an entraining air flow of 8,000m3/hr and 7,000m3/hr respectively for each hood canopy was specified resulting an a total system airflow requirement of 45,000 m3/hr. To accommodate the required airflow a belt driven centrifugal unit having a specified duty point of 45,000m3/hr @ 1000Pa with a motor rating of 30Kw and incorporating full speed control via a frequency inverter module was specified. Interconnecting ductwork located at high level was appropriately sized to maintain a column air velocity of 16mtrs/sec within the network, with flow control dampers incorporated at all connecting node points to ensure the system could be fully balanced during commissioning. To eliminate fire risk, isolation fire dampers, incorporating fusible links and single pole control micro switches to initiate automatic shut down the extraction fan in the event of fire were specified for the 600mm, 800mm and 1000mm branches of the header ductwork. To minimise noise breakout in operation the fan was fitted with a fully lined acoustic enclosure with discharge ductwork incorporating twin 710mm x 1200mm Hotchkiss noise attenuators fitted with internal pods mounted in parallel. The system was commissioned in October 2007 and fully complies with the design brief, providing effective fume extraction from the work area.

Mike Bradley AES Industrial Engineer