Carbon activated filters or ‘charcoal’ filters are often used in welding respirators to remove ozone and nuisance levels of organic vapour produced as a result of the welding process. Nuisance levels refer to those not exceeding the Workplace Exposure Standards.
What is activated carbon?
Carbon is typically made from coal or renewable sources such as coconut shells or wood. When this material is heated in nitrogen or steam at temperatures around 800-900°C, it results in the formation of a significant number of micro-pores, meaning the carbon is now ‘activated’. These small, low-volume pores help increase the surface area available for absorption or chemical reactions which take place in the surrounding air.
How does an activated carbon filter work?
When air is breathed in through a carbon filter, organic vapours become trapped inside the pore structure of the carbon substrate. The vapours condense into the pores and move their way through the carbon layer from one pore to the next. The substrate filters out ozone and nuisance levels of organic vapour, offering relief from irritation caused by foul odours or unpleasant tastes.
Are carbon filters suitable for welding applications?
Yes, carbon filters can be used for filtering out nuisance level organic vapours while welding and should be used in conjunction with particulate protection. Common applications where charcoal filters may be used include when welding galvanised steel which can give off an unpleasant taste or smell.
An optional carbon or ‘Odour’ filter is available for use with the Adflo PAPR system. The Adflo Odour Filter (part number 837110) must always be used in conjunction with a particle filter and pre-filter. Please note that the Adflo A1 Gas Filter (837542) and Multi-Gas Filter (837242) contain a carbon layer – so an odour filter is not needed when using either of these filters!
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