Advice regarding extraction

[Stevolution2023]

Hello all

Two fold reason for my joining. I am planning to get myself a MIG and then TIG welder. Had a play at work and would like to get a grip of this very handy talent to have.

But, my question for this post is ventilation.

My company are planning to install some hanging screens around the welding/metalwork area. These from what I can tell, are basically welding screens of a huge size that will hang from the roof.
These panels are somewhere in the region of 8m high by 8m wide. Two make up two sides of the 'box', and the other two sides are the actual building.

I have ZERO faith in the design, as I suspect it was Googled or similar.
Their plan is to seal it to the roof, and leave a 200mm gap around the base. The welders already have local adjustable extraction, but it isn't enough and the fumes are affecting other people in the workshop.

They then cheaped out and got a quote for an extraction fan, but then sourced their own. I suspect they are going to just plonk it on a wall with no thought to its position.
I would think it needs to be at height, but I think they are going to install it low level.

Anyone have experience of such systems? WHY they don't get it done properly I don't know (I do know... money).

Not sure of the cubic size of the space, but I can work that out.

I found this that made interesting reading:

Calculating workshop ventilation efficiently: how much power is needed?

The dimensions of workshop ventilation systems play an important economic and practical role. However, it’s not always easy to calculate them.

safe-welding.com

Thanks

 

[TEO]

Welcome to the forum, I don't know enough to give an informed opinion but I do know that there'll be experts here that can offer advice. I'm sure they'll be along soon.

 

[Anguz]

Hi, i think this gas been discussed before if you have a seach

 

[DanZac]

Extraction is a massive topic in its own right and if not done properly is likely to cause more problems than it solves.

HSG 258 (see link) is the place to start, but whilst not a particularly helpful answer I would suggest that If its a workplace that you politely remind your employer of their responsibilities under the Health and Safety at Work Act, because getting it done properly will save them a lot of grief when the HSE or their insurers come knocking.

Controlling airborne contaminants at work: A guide to local exhaust ventilation (LEV) - HSE

How to control airborne gas, vapour, dust, fumes and mist by LEV means, so extracting clouds of contaminant prior to breathing.

www.hse.gov.uk

 

[Stevolution2023]

Yea... this is already a massive issue within the company. Heath and safety isn't a priority here at all.
If I could get the HSE in for an inspection I would, but apparently they won't do 'random' inspections. This workshop fails in many places.... and quite badly.

More annoying, is we had a quote from a proper company that was very reasonable and they ditched it because they thought they could do it cheaper

 

[DanZac]

They then cheaped out and got a quote for an extraction fan, but then sourced their own. I suspect they are going to just plonk it on a wall with no thought to its position.
I would think it needs to be at height, but I think they are going to install it low level.

It really is a midfield of a topic, but you need to think where the fume is going to go, as well as where your extracting it too.

For a start your extraction needs to be as close to the source of the fumes as possible. Its pointless sucking fumes from one side of the room to the other, that's just making the situation worse.

Likewise high level extraction is unlikely to be of any benefit as your likely to be sucking the fumes over the operators face if they're bent over the work. (Probably the opposite of your assumption above)

Extraction at source using correctly designed and specified systems for the process your undertaking is the only effective way to control hazardous process within the workplace.

 

[Ross365]

I know quite a lot about chemical fumes but not so much re welding.

Basic questions would be;
>what are the fumes?
>What are the allowable limits for them?
>how do you measure what levels you have?

So with a toxic chemical, e.g. nitrogen dioxide, the limit set by HSE used to be 3ppm (IIRC) and we had an electronic gizzmo which would set off an alarm at 3ppm (which would very rarely happen because the fume extraction was adequate) . Sometimes, toxics are detected by "stain tubes" (glass tubes a bit like the old fashioned breath-alyzers).

Extraction can be defined in terms of rate of air flow (e.g. 10m3 per minute) but that tells you nothing at all about what the personal exposures are.

Another document to see is HSE HE40 which is on-line and gives you exposure limits for hazardous substances.

 

[Barking Mat]

Don't you need localised extraction vents, which are movable depending on to where you're welding, not some central evacuation.

Sound like cheap skates, not thinking of employee health, or industry standards.

 

[Stevolution2023]

They already have moveable local extraction, but the builds are pretty big sometimes, so they don't use them

Yes... cheapskates and it's costing them good employees . Trouble is, they get away with it

 

[Ross365]

They already have moveable local extraction, but the builds are pretty big sometimes, so they don't use them

Yes... cheapskates and it's costing them good employees . Trouble is, they get away with it

Well, you seem to have completely ignored my post#7, which I think gave you the most specific advice on the thread.
Are they welding through paint? This has been discussed previously on this forum.

In theory, you have a member of staff who has been assigned the responsibility of managing safety and that person should have carried out a written Risk Assessment of this problem, which presumably is the basis for choosing the extraction you already have. You have a right to ask to see that Risk Assessment. I would not be surprised if that has never been done.

I've never worked in a welding shop so I can only advise based on general H&S practice.

 

[Keith 66]

When i worked in a college we had extraction fitted to 4 welding booths, each had its own centrifugal fan mounted above the booth just below the ceiling with a drop down duct with flexible duct to an intake nozzle on a swinging arm that could be positioned to best advantage by the welder himself.
Duct diameter was 150mm as was the intake of the fan. When all four were running the noise was rather loud to say the least!
Did the job though.
But then the head of department had the contractors paint all the walls in the welding bays white. He was most put out when i reminded him of the uv flash & the H&S manager had me paint them all matt black again!

 

[Stevolution2023]

The problem is not just the fumes from the welding. They angle grind nearly all day.
There is a mezzanine around the workshop with people working on it, and you can taste the metal in the air. We left magnets out on the mezz for a day and they were covered in filings at the end of play.

They have bought some 8m x 8m welding screen to hang from the ceiling. They are then putting this fan (stabbed off Google) in the wall at some location that has not been designed at all.
The screen will be cut short of the floor by 12" to allow air in underneath, and the assumption is the fan will simply draw all the crap outside.

That just isn't going to happen

Anyway, thanks for everyone's advice