I’m trying to put together some information for our welders regarding setting up their portable LEV. Because of the nature of our work we can not work at a bench or booth etc, we have to use portable LEV which can be moved anywhere and filters the air so it can stay in workshop. 

I’m happy to describe how to position and set distance from weld pool ( and say what that distance is – ie the diameter of the hood face away) etc, but what I’m looking for is a diagram showing the general positioning of the Portable hood on the end of a flexible pipe. What I’m looking for is a side view of a welder, with weld fume and the hood positioned above / at a slight angle in front of the weld. (ie so it shows fume being drawn up and away from the welders breathing zone.)

Not looking for a real picture, but more drawing / cartoon type picture, which is copyright free, so I can use it. (just trying to avoid drawing my own). Due to the sudden change in requirement I should imagine a number of people have bought portable LEV machines and may have found some online resource for employee info / training purposes.

Has anyone come across such a resource and is willing to share?

Thanks

Chris

Thanks Paul. Sorry yes, I know how to set up myself, I want something to help a welder, just a pictorial reminder (reminding them not to have their head in weld fume!). Yes again as you say too close and then they suck away their shield gas, resulting in poor welds. Yes there will be a goldilocks zone, and also internal drafts and ventilation will also have an affect on the capture zone. What fun.

We have a portable LEV unit (well 10 of them and not the best as bought by MD without consultation). I have worked out the theoretical velocity at the face of the portable hood and I know that one diameter away from the face the flow rate (capture rate) is only 10% of that at the face. So, for us the general distance will be 100mm. However, dependant on the features ie flat surfaces or positioning the hood directly over the weld then they may be able to increase this a little as convection will be helping them. It will need adjustment to ensure capture, but 100mm is start point as there are quite a number of things to consider when setting up. I’m happy with the calculations and advice etc, and will test to find actual face velocity once we get them (so not just theoretical).

All I want is a picture, say, showing a welder on the right, in side view, the weld (and fume) in the middle and the capture hood directly above or to the left a little with a slight angle towards the weld fume, then the hoods stand on the left. This should show that any fume is taken away from the breathing zone. The info is to be used as a reminder following training on set up. This should be standard and not be any different for MIG / TIG or MMA. We only really use MIG on short runs.

Ideally, I just need a drawn type picture showing this arrangement (no other detail). The HSE do have some little videos (which is not what I want) but would have been useful for training, but they are not correct, as they keep saying they are happy with some fume escaping, which they are now not so happy with. There is a warning on web page, saying they will update it one day. Should have updated it when they changed the requirements, when did they think people would be doing the training on this subject.

So just a picture is all I’m after ( line drawing, nothing fancy), that I can add my own words to. Probably end up drawing my own, but it would be nice for once to do something the easy way.

Cheers

Chris

Chas, Yes sadly I have looked at those pictures they seem to have all sorts of  LEV Pics, except the portable type. They are the type of pic I’m looking for ( line drawing) but no portable units, and just 2D, don’t need 3D. Odd really as the HSE videos I noted above is with a portable unit, but no guidance anywhere with a picture of set up.

Thanks anyway

Originally Posted by: chris.packham

One thing I do with LEV when looking at this for clients  is use a device I have that produces a continuous plume of 'smoke'. Actually it is a mix of glycol and water and is really steam. This is ideal at demonstrating how important design and placing of the capture system is. Perhaps one or two photos using this technique showing correct and incorrect placing would be more effective than just ordinary pictures.

I read this post just before going home and had a quick internet search. The machines I found seemed to give out an awful lot of smoke, not so realistic for welding. Is there one anyone knows of that would be more representative of the actual amount of smoke /fume given off when MIG welding.  Not for testing the LEV, but for demonstration of correct and appropriate set up, so I can show what the effect of different positions are on a real example(s) of where it may be used?

I guess I will just draw my own pictures / diagrams (for a reminder document), it was worth a try and the easy way has never been for me anyway.

Chris