Tip or Arm Extraction for Solder Fume.
Solder Fume is a common airborne contaminate and the hazards to workers health posed by solder fumes (or colophony to give it its technical name) is well known.
We go in to these dangers in more depth in our Blog Post – The Dangers of Solder Fume. To put it very simply – you have to have extraction for solder fumes – regardless of how much or how little your are doing.
But what type of extraction is best?
The two main types of extraction for solder fumes are Tip Extraction and Arm Extraction. But what is the difference and why would you choose one or the other?
Tip Extraction: Advantages and Disadvantages.
Historically, tip extraction was the main form of extraction for hand soldering but it is less popular these days. Tip extraction uses low air volume but extremely high air pressure vacuum units that are designed to extract and filter fumes and debris through small bore hoses and attachments. The fumes are removed “at source” via a 5.6mm bore tube mounted on the hand solder iron. These tubes are either mounted via an Iron Adapter Kit or, more commonly now, built into the solder iron itself.
A 1.2mtr length of special ESD safe silicon hose is then either connected directly to the extraction unit or connected to a ducted system. The ducted system usually comprises of 40 – 50mm diameter pipework which runs around the factory to each soldering station (usually under the benches) and then connected to the extraction unit.
It is worth noting that the Silicone hose must be of a specific type and clear plastic hosing can not be used as it will collapse easily and is not ESD safe (as in it will generate static along its length from the air flow – see our ESD FAQ’s for more info on Static generation and charges).
An extraction rate of 28 – 32 litres of air per minute is required at each tip. It is often the case that several smaller units can be more beneficial and ensure this target is met, than having one large unit running lots of stations for the following reasons:
- Single User Extraction Units are low cost and compact and no ducting is needed.
- Ducted for systems serving multiple stations can be kept low levels under the benches.
- Larger units have a minimum number of stations they can run. As an example, a 15-station extraction unit cannot run less than 4 – 5 stations.
- Less chance of empty stations running whilst used stations are in being used.
- If the extraction unit did ever fail – total loss of extraction is avoided.
Although tip extraction can be very effective, these types of systems require ongoing and time-consuming maintenance. The tubes must be kept clean. Solder fume is a very sticky fume and leaves a residue behind. This can build up quickly in the tubes and block them. A blocked tube will stop the extraction from working. Tubes can block in a matter of hours. The steel tubes need brushing regularly – several times a day. The silicone tubes need to be checked several times a day for blocks.
If a section of silicone hose does block it will have to be replaced. Steel tubes will need replacing regularly as well – as once the residue for the fume “sets” it can be extremely difficult to remove.
Ducted systems are also difficult to remove or move if the factory lay out changes. These days most tip extraction systems use push-fit ducting – which can be taken down for cleaning and relocation.
Solder tip extraction can be a good solution to controlling the dangers of solder fumes but only if the maintenance of the system is kept up to ensure it is in good working order at all times. Tip extraction most commonly fails because the amount of attention it needs to keep it working is underestimated.
The steel extraction tubes on top of the iron can also block line of site on fine solder work. They have to be placed close to the solder tip and this can mean they get in the operator’s way.
See our Tip Extraction Best Practice Guide for more information.
Arm Extraction
Arm extraction has, in recent times, become the most common form of capture and extraction for solder fumes. It costs slightly more to set up than tip extraction systems but there is vastly less maintenance involved.
Solder extraction arms usually connect to small, under the bench filter units that usually run 1 – 6 arms. The arms size is usually either 38mm or 50mm with either a funnel nozzle or pen-nib nozzle on the end of the arm.
For solder fumes a minimum of air speed is given at 10 meters per second and arm extraction systems for solder fume must legally meet this.
As arm systems do not often require ducting, they can easily be moved around the work space as needed and can be much more flexible than tip extraction. By using arms, the extraction units can be used to extract other harmful airborne contaminates (depending on filters being used) such as potting or dipping.
The biggest advantage is the lack of constant maintenance required to keep an arm extraction system working. Unlike a tip extraction system there are no tubes to constantly clean of blockages or to replace.
The capture arms themselves also are placed just behind or to the side of the soldering point – dragging the solder fume away from the operators breathing space before it reaches them.
With arm extraction, unlike tip extraction, there is no stainless-steel tube on top of the iron to get in the operator’s way.
Advantages for filtered arm extraction systems are:
- Ease of installation: plug and play set up.
- No high level or unsightly ducting.
- Small units can be easily moved.
- Only stations being used need be turned on.
- No balancing of airflows needed.
- If one unit ever fails – total extraction is not lost.
- Low running costs.
A note on centrally ducted arm systems.
Some solder fume extraction systems that use arms can be vented to atmosphere. This is more common in factories with a large amount of solder stations.
These can be useful but have several disadvantages.
- Large systems have high level, large diameter ducting systems.
- The whole system needs to run at once – so stations not in use will still be running.
- Running costs can be higher.
- “Make-up” air or warm air may be needed to be added to the working area as central ducted to atmosphere systems do not clean and then recirculate the air – they remove it. This can lead to increases in heating bills.
- Can not be easily adapted or moved.
