Controlling Solder Fume (& other small scale emissions)

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Exposure to solder fume is one of the top 8 causes of occupational asthma in the UK.

A couple of weeks ago, Diamond Environmental posted an article on controlling solder fume on their blog. It’s worth reading, and can be found here: Controlling Solder Fume

To summarise, it says that two of the most common types of extraction controls: flexible arm captor hoods and low volume high velocity (LVHV) tip extraction are usually ineffective at capturing the fume. The former because the captor hood is normally positioned too far away from the work, and the latter because the tube is often not close enough to the tip, and the tubes need cleaning out more often than is usually done or they get blocked up.

It concludes that whenever local exhaust ventilation (LEV) is used as a control method, the best type of hood is usually a partial enclosure which contains the source, and that this is the most effective way of controlling solder fume. Here’s a short video showing how solder fume is contained within a booth.

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I agree with the article, and I would like to add a couple of further points, and some words of warning.

First the warnings:

In electronics catalogues, one can find “fume absorber units” for use when soldering. These are cheap, but are poor at capturing solder fume, because they don’t enclose the source, and are usually fitted with carbon filters which are practically useless at trapping the fume, so it is just emitted back into the workplace. In my opinion, they should be banned from sale. The HSE could do this with individual suppliers by using Section 6 of the Health and Safety at Work Act, which imposes duties on suppliers etc. so that articles are constructed and designed in such a way that they are safe and without risks to health.

Other, more expensive, filtration systems which recirculate air back into the workplace, in order to reduce heating costs, are usually fitted with HEPA (high efficiency particulate air) filters which are more effective at removing the fume. However, their effectiveness depends on the correct seating of the filter, otherwise the fume can just bypass it, and this should be checked every time the filter is changed. Extracting the air to outside may be safer.

Some further points:

In some cases, an enclosure may get in the worker’s way. To improve accessibility, at least one firm has installed their extraction booths on sliding rails. You can see in the photo that the booth also provides a barrier between the worker’s breathing zone and the fume.

Enclosure hood on rails

This type of booth definitely also has applications for small-scale work other than soldering, e.g. handling small quantities of solvents or powders where a proper fume cupboard is not required.

For soldering, other simple measures can be used to help keep the worker’s head out of the plume of fume, such as using an illuminated magnifying glass. However, this won’t prevent fumes building up in the room.

In most cases where soldering is carried out, measurement of personal exposures is a vital step in the risk assessment, and in evaluating the effect of any changes in the controls used.

(Thanks to Mark Piney for the photo and the video clip)

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