Measurement of the performance of air cleaners against the particulate element of rosin-based solder flux fume.

A number of commercially available air cleaners designed for use against solder fume have been examined. The fume capture efficiencies have been measured with a tracer gas comprising a neutrally buoyant mixture of sulphur hexafluoride and helium, and the filtration efficiencies have been measured using solder fume produced at a constant concentration, laboratory-generated monodisperse aerosols, and standard aerosols. The extractor volume flow rates of the simpler types of fume collection units, measured by us, differed from those reported by manufacturers. The capture efficiency of these units was good when the soldering iron was less than about 20 cm from the air intake, but the filtration efficiency against particulates and, therefore, the protection offered, was poor. More robust LEV units containing a HEPA filter had a similar capture efficiency, but a filtration efficiency that was well above the standard strictly necessary; such units will give good protection if properly used. The tip-extraction type of system was found to be very effective but the extraction nozzle rapidly became blocked with the rosin in the solder. Subsidiary measurements of vapour filtration efficiency were made. Activated carbon filters in the form of foams, used with the simpler type of cleaner, had negligible filtration efficiency against either particulates or vapours and would, therefore, offer no protection against any hazardous component of the fume. The granular carbon filter in the tip-extraction system was an effective vapour filter.