Extraction Systems for Pollutants
Soldering fumes must always be extracted
Efficient filtering prevents health risks
A typical electronic solder wire has, along with tin, copper and silver, also flux material, which makes up about 2 to 4 % of the wire weight. Without the flux material it would not be possible to manually solder these wires with soldering irons or hot air flow devices. During the soldering process a portion of the flux material in form from soldering fumes will be released – by lead free soldering is the fume accumulation greater, this is due to the higher temperatures that are necessary to solder lead free wire. The flux material is composed of various resins, acids and activators. At low temperatures it forms the typical resinous rim around the soldering point. At high temperatures the flux material decomposes, forming a cocktail of various materials that is primarily comprised of water vapour and fine dust.
Ventilation or extraction is necessary
In accordance with prevailing regulations, the trade named solder wires sold by Distrelec do not constitute dangerous goods. It is the occupational exposure limits that are important in the assessment of risk associated with manual soldering. Research study has shown that the contamination with respirable fine dust, at a soldering tip temperature of 350 °C and 3,5% flux material and without extraction or ventilation, have a factor of between 1,1 and 17 above the occupational exposure limit. This is completely different when an extraction system is used, then the exposure decreases to a minimum.All solder wire manufacturers and occupational health and safety experts recommend using extraction equipment when soldering. The fine dust contained in soldering fumes can penetrate deep into the lungs and may cause long term damage. Therefore, inhalation of soldering fumes is to be avoided at all times.
90 minutes of soldering with lead-free solder wire — do you want the residue in your lungs?
|The figure illustrates the correlation between the particle size (left), and the depth of penetration into the lungs (centre). On the right-hand side, the mode of operation for a three-stage soldering fume filter is presented. It is clearly visible for which particle sizes the respective filter stage is designed. See below for the filter structure.|
Selection criteria for soldering fume extraction
Point extraction vs area extraction
Point extraction  occurs directly at the soldering iron. Disadvantage: Handling of the soldering iron is impeded. Advantage: A lower air volume is required.
Modern, highly efficient extraction equipment use a three-stage filter system consisting of:
- Class F7/F8 coarse filters
- Class F13 HEPA filters. Achievable removal level > 99.995%
- Gas filters with potassium permanganate as the oxidizing agent, and active carbon for the absorption of residual particles
On the one hand, an extraction system must be strong enough, but the filter must not "compress" the air:
For the installation of a modern soldering fume extraction system, only a 230-volt power supply is required as the devices operate in recirculation mode. This is possible due to the very high purity of the filtered air, which can therefore subsequently be reintroduced into the ambient air. The extraction system is adapted to the individual soldering workplace using adjustable pipes and suction nozzles. The variability of the suction nozzles is important to ensure that the workplace ergonomics and extraction system operate in unison.
TC Kristall 400
Solder wire with low flux-powder content.
WT 1013 soldering station set
Compact, stackable 95-W soldering station.
Improves soldering fume absorption
When soldering, it's essential the fumes generated are collected and extracted to reduce the risks of nasal irritation and occupational asthma. Two different forms of fume extraction methods are used. The first is to use a solder tip extractor attached to the tip of a soldering iron that draws fumes through a filter system. This is known as solder tip extraction. The filter systems are fitted with special fume filter cartridges that remove toxins in the smoke and return the purified air to the workplace. While this method is suitable for one or two workstations performing soldering only, it is not effective for larger applications, especially where other fume-generating activities take place, including gluing and the use of solvent-based chemicals. This is where volume extraction systems are more effective. They are fitted with larger hoods that are capable of extracting greater volumes of air and fumes. A range of fume extraction accessories is available, designed to increase the efficacy of volume extraction systems. These include extraction nozzles, extraction kits, extension hoses and brackets. A complete selection of filter cartridges is stocked to maintain extraction systems in good order. Suppliers of this equipment include Weller FT, Metcal, Elmi and Xytronic.