Welding area – roadblocks and solutions | summer 2022

There has been a degree of silence on the welding area for some time now, but that doesn’t mean people haven’t been working hard. @Marcus6275 has been pursuing various companies to find out what equipment we would need to extract fumes from the room.

As of today, the cost is looking to be £2,000+ for the industrial type fans we would need over such a long duct run.

There are several potential solutions, all of which have pros and cons. This thread is an open forum for anyone to discuss the issues.

Below is a summary of solutions discussed so far in the metalwork team Telegram chat:

  1. A mobile extraction unit could be acquired for around £600-1,500. This may limit the room to one person welding at a time, and would (probably) still require some external exhaust system to send the gases outside the space

  2. We raise the £2,000 for the industrial fan, then several hundred £ for the ducting, filters, etc.

  3. We keep an eye on eBay for a second-hand fan, although the team is struggling to understand the specs of machines and their suitability for our use case. Professional companies only seem willing to advise if they see a sale.

  4. We seek grants or sponsorship (nothing more concrete than that at this stage, but it’s an option)

  5. We relocate the welding area to a room at the front of the space, so duct runs are shorter and the cost reduces accordingly. This would obviously affect the whole space and would require broad buy-in.

the suggestion I made before a few times, and I’ll make again, is that welding goes where large project storage is, and large project storage goes where welding is.

Swapping those two around work just work.

Some people objected to this because they wanted metalwork and welding together, but the front rooms were and are too small. Plus they’re now occupied by other areas of the space which waited for the metalwork team to make a decision before moving into them.

So either there’s a pledge drive for the back room to get ventilation, we don’t have welding, or we actually do get welding, but there’s a very short (and tall, and wide) walk between the two.

I know many people would actively join the space because it has welding. I can’t imagine anyone who would refuse to join because the two rooms weren’t adjoining.

So that’s my 2c - swap large project storage and welding around and just get on with welding. We could be up and running in weeks.

I’m broadly in favour of this (although there might be some questions about how to make the new welding space airtight).

Could large members storage go to the back of the space, though? That way you don’t have people manoeuvring big objects through a workshop?

There have been many forum posts on this topic, below are several that may also help provide additional context:

I’m currently at work so unable to add much more context to this till later. But to clarify moving to the front doesn’t immediately fix the issue.

The cost of the fan is because it needs to move the fumes over 20m. I’ve had £2k quoted to me over the phone as an estimate, on eBay you can find them much cheaper but its very hard to check whether they are suitable. Additionally it has been confirmed to me that any type of extraction must have a filter which is another cost I hadn’t been able to factor in.

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I put together a parts list of only the metal ducting required to run from welding to the front. This is only a rough estimate and didn’t include the fan or electrics

Attached is the plan I sent to a supplier when asking for advice/guidance.
Welding Ventilation.pdf (3.2 MB)

Personally I tend to agree with Connor in terms of keeping metalwork where it is and having welding in it’s own separate area near the front if possible.
We could wheel the metal bandsaw across since it’s on casters (assuming it was still working) if it needed to be used.
And what is currently the green area is just full of long terms storage that maybe we could move to the back part of old weldy perhaps. Maybe keeping some of the things still in there (such as the sheet press) more towards the door in old weldy.

At the time we did the first plans we didn’t know that you’d need a bigger fan based on how far away the location was. (Personally I just thought it’d be any old fan and some pipework) and I didn’t like the idea of shrinking the metalwork area down at the time ether.

Things to think about would be

  • How to wall off the area at the front.
  • There will still be costs for filters / fans etc even at the front as Mark has mentioned already
  • We could probably start with single phase for one of the smaller welders then move onto 3 phase later on perhaps depending on the cost of the cabling etc.

I think the idea of moving large storage to the room off metalwork has big problems. Mark and I discussed it last night, and it’s going to put a lot of foot (and object) traffic through metalwork, which isn’t ideal for the people using the storage or the people using the workshop.

There are issues with putting welding in the front room, not least:

  • We’d need to seal off the green room for fire reasons and we have no more bricks left
  • We’d still need to pay £££ for fans, filters, and ducting
  • We’d probably need to do some electrical work
  • Apparently (this predates my involvement), members rejected having welding in that room for… reasons unknown to me

There’s the opinion that a high-grade fixed extraction system represents the best long-term investment, but this depends on the funds the space is willing to release. This, in turn, depends on the interest that the membership shows. I had 16 people respond to my welding survey (not always the most reliable indicator) but the cost per user starts to look very high in that context.

As we’ve dug more into this topic (welding fume extraction) we’ve learned a lot, and we don’t want to bodge a solution. What might seem simple comes with complexities about fire regs, etc. etc.

I would favour a dispassionate cost/benefit analysis of our various options, which I’m happy to undertake once I’m back from holiday.

But I am willing to consider any and all solutions ranging from “sack it off and sell all our welding stuff” to “invest £10,000 in a professional solution”. Nothing’s off the table as it stands.

Another option, possibly a bold one, is to get rid of, or drastically reduce large project storage.

It’s fantastically abused. Most of the stuff there is covered in dust and are “I’ll get to it some day” projects. That’s never what it was designed for.

When we have had actual large projects, such as the furniture and speakers, people just use the huge space by members storage instead.

So it’s not being used in the way it was designed for, and it is being used in ways it wasn’t designed for.

The room next to metalwork will find some other use - either as an extension of metalwork or visual arts (perhaps an entrance from the stage to make a clean room)

Found some time to add context/all the research I’ve done on this over the past year. I think this is everything and I’d be happy to discuss further if people have questions. Unfortunately I think I’ve reached the limit of how far I can take this and will be stepping back. If we manage to source a fan I will be happy to step forward and help again.

I would like to also personably add that I am disappointed to see that one of the first knee jerk reactions is to move the welding after the sheer amount of effort has been put into what we’ve built so far, given it was a decision was made by members back in December 2019 as to where welding was to live.

While I agree large projects is misused I don’t want to see return to large projects blocking tool access in the workshops again. I am aware other spaces in the country don’t offer storage space at all so while it would be possible, and with rising costs is a good questions to ask whether its an effective use of space, it would likely take a lot of effort at the beginning for members to keep on top of, which typically falls to a select few to manage.


Defining the scope of the extraction has evolved over the few years trying to get welding up and running as members have been suggesting/requesting more options and features.

The first and primary requirement is that the ventilation/extraction it is suitable for welding gases and particulates. This means that MIG, TIG and Stick welding are all able to be done safely with sufficient extraction. The metalwork team agreed during a team meeting on the 10th April 2022 a layout for the room including the extraction for welding. This included two LEV arms and a possible ground level intake for heavier gases such as Argon.

One of the additional suggestions for the extraction infrastructure was the ability for spray painting. While this would certainly be possible, my research in to this indicates it would be a complex and restrictive process as paint fumes can be flammable.

Room Location

Most members should be aware that the ‘Welding room’ is located in the back right hand side of the space as you walk in the main entrance. The room is surrounded on all four sides:

  • Behind = Lift shaft with a new wall recently built to separate the two rooms
  • Left = Metalwork room/rest of the space. Continuing left takes you to the corridor between woodwork and the dance studio.
  • Right = Another unit we do not have access to.
  • Front = Visual arts/rest of the space. Continuing forward reaches the external wall that leads on to the street.

The room was originally much smaller as it was two areas (Welding & Grinding), however the metalwork team with help from members demolished this wall and built a new one closer to the lift. This nearly doubled the total room size and improved accessibility as it removed the single door choke point to the welding room.

Why is it back here & can it move?

November 2019 I wrote a proposal to rearrange several areas of the space, including metalwork and welding to the front of the space to account for the challenges such as installing extraction at the back of the space would bring. (Hackspace Modification Proposal)

This was turned down by a vote at a member meeting on the 2nd December (Can’t find minutes unfortunately). From that, the space (those active in the infrastructure work) determined that the location was now fixed and would not move without a significant requirement for an overhaul of the space. This meant other works, such as setting up large project storage and Parkspace, could start without the potential for them to be relocated and progress lost because “welding is in the wrong place”.

Extraction routing

Because the room is surrounded on all four sides there is no easy route for the extraction to take. At a minimum the distance is at least 20m.

The current route that I have been working on has the ducting run along the far right wall by Visual Arts all the way to the front of the space. At the front of the building is an old window that @mikeh and I recently boarded up to improve weather proofing and security. The boards are two 12mm OSB sheets so would be easy for the ducting to pass though.

Contacting Suppliers

Ove the past few months I’ve been contacting various suppliers. In the last two weeks I’ve been able to make the most progress. Typically in my experience I’ve struggled to get responses from companies

22nd July I emailed the ventilation company Duct Store asking for advice on the routing and selection of parts. On 25th July I got a reply and from there I contacted two more.

Duct Store

Q1. I spoke with one of your colleagues who confirmed that the metal centrifugal fan DV200 (P&G Fabrications (Essex) Ltd. 200mm Dia Inline Duct Fan) would be suitable, but only for fumes. If particulates were a risk would a filter upstream be required/possible, and if so what would you recommend?
A1. The DV200 would not be suitable over that duct length. I recommend you speak to Axiar fans who should be able to advise you if you supply them with the necessary info regarding duty and duct length. https://www.axair-fans.co.uk/. I note that the Nederman arms require an airflow of between 700-1000 m3/ph. The DV200 would only achieve this with a short duct run.

We are sheet metal manufacturers so I can’t help too much with fan technical.

Q2. Where would the fan be best situated? Intake, midpoint or exhaust? Or due to the length would we require two fans?
A2. ~ no answer ~

Q3. I know that this system will require at least one fire baffle as the welding room is a separate fire zone to the main area. I would be specifying the CFDIN 200mm at the wall, I assume this should be positioned on the main area side?
A3. Fire dampers should be installed in any fire break or fire resistant wall, either in the wall or very close.

Q4. As this ducting will be running along a wall, we are planning on using unistrut cantilever arms. The FAQ page shows the support rings hanging under the unistrut. Is this advantageous over having the duct sat on top of the unistrut instead? Due to the arches, having the duct hang under would lower our head room and possibly cause accessibility issues.
A4. We can supply U-shaped brackets to enable the duct to sit on top of the cantilever if required.

Q5. At the external wall, can we just terminate at the wall with a standard exhaust valve, or would we need a special fire rated one such as EVFR200. Or do we need to run the ventilation up the building to a certain height like a chimney? (We’re on the ground floor out of 5).
A5. You will require a beak (exhaust valves are for internal use and not to be used as you suggest). We do two types of beak – one an off the shelf lighter version, and a type we produce ourselves. Alternatively a grill box and louvre.

Bird Beak | Duct Terminations | Spiral Duct Fittings | Ductstore

Meshed Ducting Bird Beaks | Spiral Ducting Fittings | Buy Online

Aluminium Louvres | Grilles & Louvres | Ductstore Ducting Supplies

Grill Boxes Top Entry | Rectangular Grill Boxes | Duct Supplies Online

Running up the wall depends on whether or not the exhaust is going to be a nuisance to neighbouring buildings. Note that longer ducts runs will affect fan selection.

Westermans International Ltd

After the reply from Duct Store I rang Westermans International Ltd as I saw an advert they sell second hand welding equipment & extraction. On the phone I discussed with one of their technical team and explained our situation and the potential options of having a mobile extraction unit.

On the phone the guy advised me that regardless of the setup a filter is required. Filter medium can be the same as spray paint booths or kitchen hood extractors, however filter medium is flammable and a spark arrestor would be required. I asked where this was written and was directed to the HSE website (Local Exhaust Ventilation (LEV) workplace fume and dust extraction - HSE)

When asking about the fan they recommended that for the 20m distance a 2.2kW 3ph fan would be required. The price range for something like that from them would be in the region of £2k. A smaller portable fan N24 was available for £700 however the guy on the phone wasn’t sure if that would be sufficient. The recommendation I was given after I mentioned we were looking at a budget of £100 for the fan alone was to just search eBay and Bid spotter.

I asked about the mobile filter units and was quoted £1500 for new and £1200 for second hand. Again cheaper can be found on eBay and Bid spotter, I saw one recently close for £625. The issue with these is the filter replacement cost can be in the hundreds. Another alternative was renting the mobile unit but that would cost £150 a week with a two week minimum period.

Axair Fans

I finally rang Axair fans and they echoed Westermans estimate of £2k for the fan. The additional info they gave me was that it would likely need to be a centrifugal fan and not inline/axial. On the phone the recommended I send them a plan of the routing so they could specify a fan and provide a quote. I sent an email with the plan as of today (28/07/22) and will edit this post with their response when I get it.


The parts can be split into a few categories:

  • What we already have
  • Ducting parts required
  • Electrical parts required
  • Machines and Equipment

I cannot speak for the required electrical parts but I understand that 3ph being an original requirement was part of this. Equipment and machines is currently managed by the metalwork team

What ducting do we currently have?

The space currently owns 4 lengths of 200mm (8”) steel spiral ducting.
3x 3m long and 1x 2.4m long.
As a rough cost for reference purposes, a 3m length of 200mm = £30, 150mm = £20 and 100mm = £15

In December 2021 I was able to buy several welding extraction arms. In total I bought six and the metalwork team agreed to a layout that would use two. These arms have a 1.5m 360deg reach and a 150mm ducting connection. The cost of these to the space has yet to be negotiated as I am in the process of selling the excess. My intent was to try and cover all the costs with the sold items so the space doesn’t have to pay for the two it’s using.

I cannot speak for the equipment we have but forum posts linked in a post above have more detailed information on them.

What ducting do we need?

As linked above I created a parts list for the ducting and fittings I believe we require. This list isn’t complete and further costing is required to find the cheapest parts. I also haven’t had time to update this with the recent information. Major components are:

  1. Fan:
    The fan is an obvious requirement as is our biggest roadblock. Originally I was advised that this could simply be the same as a commercial kitchen extractor fan with the key requirements being that it must be metal and fire rated however speaking to companies this doesn’t seem to be their advice.

    The recommendations by Westerman’s to look on eBay and Bid spotter while the most cost effective has the risk of us buying something that isn’t fit for purpose. The only way this would be a viable approach would be setting up a predefined plan and having someone keeping an eye out for possible options. Getting the necessary details of fans on auctions is often difficult/impossible until after purchase so the only sure way is to find one that is/has clearly been used for welding, and is ‘big’ (has high airflow).

  2. Fire baffle:
    As the extraction would be passing through fire zones a fire baffle is required. Several options are available, from what I can tell one of these would be suitable: Circular Fire Dampers

  3. Filter and spark arrestor:
    With a rigid system filters typically have a ‘filter box’ that the medium is placed inside such as: Duct Filter Boxes | Galvanised Filter Boxes with Filter | Ductstore
    For the spark arrestor prefabricated options are available or some companies will fabricate to order ones out of metal mesh. These appear to be very expensive at first look: https://www.ducting-express.co.uk/product/spark-trap-200-diameter
    They also aren’t considered a complete solutions so other items may be required

What are the unknowns

My primary focus has been finding a suitable fan, as such I had not had the chance to answer all of my questions that I think we would benefit from having the information for. This isn’t a complete list of all our unknowns, just ones I can think off:

  1. Where does the fan need to be installed along the run (intake, middle, exhaust)
  2. Is 3ph required for the machines/fan (would depend on fan spec)
  3. Could two fans be used
  4. Filter medium type
  5. Can we fabricate a spark arrestor ourselves/cheaper options
  6. Can a mobile filter unit be used with Argon
  7. Can mobile filters be replaced with cheaper alternatives
  8. Can mobile filters be cleaned/reused
  9. Limitations/risks of spray paint extraction using the same ducting
  10. What is the service life of the fan/does it ever need maintaining
  11. How often do filters need replacing/cleaning

Why was this not apparent from the beginning

Some may question why none of this was made apparent sooner and the honest answer is that the past year has just turned into a fact finding exercise. It seams that when welding was suggested, ‘facts’ had been presented with a lot of “I think” statements have caused us to questions what is/isn’t required, which in turn has caused more confusion and delay. Unfortunately the people who had more experience and knowledge on this subject matter that were part of the original discussions have since been unavailable due to various circumstances.

Going forward I hope this post helps clarify and cement the facts while outlining the unknowns that still need to be researched.

Also worth noting that the cost of parts back in 2019 was much lower than it is now so that’s been a massive impact on this. The double whammy of Covid and Brexit has really made stuff expensive and difficult to source.

Moving to the front

Speaking hypothetically if the membership took the decision to move welding to the front of the space, then the only significant change to the ventilation would be that the fan required could be smaller. How much smaller is an unknown but I asked Axair to size one for a 5m run as well.

The implications on the space would be much larger as at a minimum new walls would be required. After the wall separating the welding room and lift shaft was built all the breeze blocks were thrown out so new ones would need to be bought. If plasterboard was used instead while we have some metal strut’s left over from the metalwork walls the plasterboard is still very expensive and a single layer is only rated for 30mins. For reference the metalwork walls cost a little over £400.

There have been a couple members showing interest in potentially funding welding in the hackspace recently and since my last message I’ve been keeping an eye out and found some new options that may work for the space.

1. Another possible fan option

I spotted this fan on eBay and on reading the description noted the following:

Its high pressure capability means also that the duct runs can be quite long up to 50ft in length and the fan will still work well.
If you go to 200mm duct diameter you can use this fan on 100ft lengths (smooth bore stuff)

So, at 200mm diameter (which we’d be using) this fan in particular can apparently work for 30.5m despite only being 0.55kW.

This would need someone to contact the supplier and check its suitability for weld fumes/particulates (even with us using a filter). They appear to have several fan options available and various sizes so its possible they’d have something suitable if this one wasn’t, and they’re all cheaper than the £2k I was quoted previously.

2. Mobile filter unit

The option of using a mobile filter unit for welding in the hackspace has been proposed a few times but due to the costs associated, in the past this typically wasn’t a viable option. A new filter unit can cost a couple grand, and the replacement filters required can cost several hundreds, making it a costly piece of equipment to maintain in the space.

However, I found this filter unit on eBay.

The listing has ended with it unsold but has been relisted at least once since I spotted it so may still be available. New this one would retail at £1.7k. At this moment in time there are a couple other versions of this filter unit with price under £500.

When looking into what the cost of a replacement filters would cost, I found them to be £60 for the pre-filter and £230 for the main filter. That said I am not confident in this as my research has only been to check the filter unit datasheet and google for the filter size/brand name. I’ve not spoken to any supplier and got confirmations on this. As such it would need someone to research and check that those costs are correct. The cost of replacing filter would have to be incorporated into the usage cost of welding so it needs to be accurate so the space isn’t stung with unexpected costs.



If we did go down this route it may eliminate the need for the duct work out of the hackspace, however there is some unknown as to whether this is true as the filter unit wouldn’t remove the built-up of inert gasses (argon) used when welding which on built up would be a hazard. Additionally we aren’t 100% sure what type of welding and materials are suitable when using a mobile filter unit.

3. A fan unit thing I found while writing this update

Finally a quick search on eBay with terms such as “fume extractor” etc will show many options. This one linked below appeared just now and might be suitable, but is an example of where we would require some contact with the seller to find out the exact details of the fan to ensure it would be powerful enough as the listing is very bare bones. Even after contacting and getting extra info we may want to contact the manufacture to double check just to be sure.


Just been on the phone to the insurers. We are not currently covered for welding as it is not classed as a standard hackspace activity. They are happy to add it, but it will be a case of our broker going to the insurer with evidence of our safety process and photos of our welding room and then them agreeing a price based on that. He suspected somewhere between free and £50 (7% increase on our existing bill) per year.



Cheers Joe. With one thing and another going on, I’m so involved in day-to-day stuff I’ve not had time to even look at moving welding forwards. But will bear this in mind when the time comes.

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Thought this might be of interest, Bristol is just about to launch their welding and put together this purchase proposal document to get member support.
welding_proposal.pdf (516.3 KB)

Just revisiting this myself
The Bristol proposal looks very interesting

They’re using one of these which looks cheaper than the ones we’ve looked at - £990 ex vat, £1188 inc vat

My thoughts are similar to before, split the extraction into 2 parts

  • First use the above £990 portable extractor for welding to filter out the fumes / particulates etc, which should in theory be enough on it’s own.
  • Have a secondary extraction which isn’t welding specific and can be used for getting rid of paint fumes or trace argon gasses
    Basically a pipe / vent on the wall

Since the secondary extraction isn’t picking up anything hot we don’t need to worry about special fans or fire baffles
We could use a fan similar to what’s been using for the laser extraction and we could use some of that bendy flexible pipe overhead of the visual arts area which would be safer to keep up
It could also be used to pick up any paint fumes if someone decides to spray paint in there

Shopping List

So in total around £1298 approx which is less than the 2K we were originally looking at
Although sorting out the stuff in that room is probably one of the next things to look at before that in terms of the insurance etc

Yeah I saw their setup today and it looked good.

It could be worth inviting some of the folk who were involved with it over here? They can sign up as online only and maybe we could borrow some of their wisdom?

Over the months (and years) this has been rolling on, I’ve slowly begun to form the opinion that a welding workshop would be a bit of a stretch for us to run. Right now we have several work areas, very few of which run at a satisfactory level in terms of resourcing, training, and maintenance. If we added welding, it would be yet another list of jobs for us to keep on top of, with questionable benefit for the members. Demand is fairly low, according to our own research.

Looking at our organisation with a completely cold business hat on, very few people would recommend adding another area of operation. And as the person on whose lap the burden of devising and delivering some kind of training programme would fall, I’m not sure how I’d fit that into my life.

I could even argue that the above points have been proven true in reality. Given that members are empowered to make change happen, and nobody has been able to make welding happen in 4.5 years, that seems like proof that the collective will isn’t there.

HAVING SAID ALL THAT, the above extraction system is broadly what I/we have in mind, yeah. If people do want to move that forward, I’d be happy for that to happen, and I’d support them where I could. But I’d rather spend my time getting our existing stuff in order first before we add a welding room.

(I’ve no opinions either way on the above, as welding is way beyond my experience and needs :smile:)

We have some surplus spiral ducting left over from the laser ventilation work, in case it might be useful for welding or any other general ventilation work:

  • 2x 150mm in 3 meter lengths
  • 1x 100mm in 3 meter length

Currently stored by the stage, against the column near the Mac. I can move it into the back storage/welding room next time I’m in if that’s okay with yourselves?

I’m going to try and move forward with this.
The way I see this working is in 4 stages

  1. we run a flexible pipe across from the weldy area to the outside with a normal extractor fan in the middle (same as the laser cutters). approx cost £110 or less if we re-use some of the pipe mentioned above.
    This could also be used for extracting fumes for paint spraying in that area.

  2. we (me or Ben) setup ether a 16A or 32A socket on the wall in the weldy area.
    The reasons for this instead of a normal socket is so that we can avoid people trying to run a welder on a normal extension cable, and if we use one of those cheap CUT50 plasma cutters they take a little more than 13A when on the full setting

  3. We clear / setup the room for welding (I can take the scafolding back if it’s no longer needed)

  4. We get the £1200 portable filter thing as a last step

I’m going to put in a purchase proposal for stage 1 above as a starting point.
Drilling big holes in the wall and fastening brackets to the ceiling for the pipe will probably be the difficult bit, if we can get that out of the way then it may help to give the rest of it a push.