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.
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”.
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.
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.
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.
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:
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).
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
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:
- Where does the fan need to be installed along the run (intake, middle, exhaust)
- Is 3ph required for the machines/fan (would depend on fan spec)
- Could two fans be used
- Filter medium type
- Can we fabricate a spark arrestor ourselves/cheaper options
- Can a mobile filter unit be used with Argon
- Can mobile filters be replaced with cheaper alternatives
- Can mobile filters be cleaned/reused
- Limitations/risks of spray paint extraction using the same ducting
- What is the service life of the fan/does it ever need maintaining
- 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.