What you should consider with welding fume filters

Posted by André Faber on Jan 19, 2021 9:22:59 AM
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Purchasing a fume extraction unit is the first step in the right direction. To protect the welder and other endangered persons from the dangers of welding fumes for as long as possible, there are a few things to consider, especially when it comes to the fume filters. The fume filter ensures that the hazardous gases in the welding fumes are filtered out and that the working environment is safe for everyone. How exactly does that work?


How fume filters work

The fume produced during welding is sucked in by the fume extraction unit, flows through the welding fume extraction torch, extraction arm or extraction hood. Then the fume reaches the filter and flows through it. No filter can remove all harmful particles from the welding fume. But the finer the filtration medium, the smaller the fume particles that get trapped. The cleaned air is led back into the workshop. It is the opposite for the size of the filter: the larger a filter surface is, the more particles the filter can absorb. However, in order for a mobile welding fume extraction unit to still be practical and also actually mobile, the filter size cannot be too large either.

The types of welding fume filters


There are both fume extraction units with non-cleanable and cleanable welding fume filters.

Filters that have a kind of cassette shape usually need to be replaced regularly. When the filter is full of tiny filtered particles, a new one is needed. These filters are disposable filters. 601_0008_1-Main_filter_cartridge-MHow long should a filter cassette last depends on the welding time, the welded material, the welding parameters and the preparation of the material.

If the fume extraction unit is used intensively, it should be an extraction unit with a cleanable filter. In this case, either an automatic cleaning of the filter is integrated in the extraction unit or cleaning must be done manually.

The W classes of welding fume extraction filters

There are different filter classes, which can be classified according to their filtration efficiency. Depending on the material being welded, one of the three filter classes must be selected. In particular, it is important to choose the highest possible filtration efficiency for hazardous, carcinogenic substances. These filters, which are classified as filter class W3, have a separation efficiency of 99 %. They should be used with high-alloy steels. The next lowest filtration efficiency is still greater than 98 % and is categorised as class W2. These filters are suitable for alloy steels with 5-30 % nickel or chromium. Class W1 has the lowest filtration efficiency with at least 95 % and should be used for unalloyed or low-alloy steels.

Filter class
Seperation (%)
W1 ≥ 95 Non-alloyed steel, alloyed steel with alloy components e.g. Ni and Cr, low-alloyed steel, x ≤ 5 %
W2 ≥ 98 Same as W1, plus alloyed steel with alloy components e.g. Ni und Cr (5 % ≤ x ≤ 30 %)
W3 ≥ 99 Same as W2, plus alloyed steel with alloy components e.g. Ni and Cr (highly alloyed steel with x ≥ 30 % Ni-based alloys)


Cleaning welding fume filters

As welding fumes contain oil, the welding fume filter can quickly become clogged. Therefore, regular cleaning of the filter is necessary to keep the extractor working for a long time. Regular cleaning protects the unit from suddenly no longer extracting and perhaps even being permanently damaged. If the extraction unit has an automatic cleaning process, cleaning starts automatically after each welding process. However, even with automatic processes, it should be checked at regular intervals whether the cleaning function is working properly. Often there are also signal lights that indicate when the filter is full and needs to be cleaned. By then, it is usually so difficult that the automatic cleaning system can no longer do it on its own and you have to intervene manually. Of course, the filter cartridges have a longer service life than the filter cassettes, but they also wear out at some point and have to be replaced.

Feel free to contact us directly and we will be happy to advise you which fume extraction unit with which type of filter is the right one for you.

Would you like to take a more detailed look at the different welding fume filters? Watch our video on the xFUME FLEX with filter cassette or our video on the xFUME ADVANCED with filter cartridge (english subtitles available)!

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Topics: Fume Extraction