Posted By Descarte
Does any one know of a UK or perhaps scottich supplier/installer of retractable LEV for use at various points sources in say a lab where it can be moved out the way if not required. Fume hoods / cupboards are not appropriate in this case.

I have searched for such but cannot find any suitable companies in the UK.

Also if any one has had any positive prior experience I would be glad to hear of it, and in what application.

Thanks in advance

Des

Posted By Chris Packham
Retractable LEV systems need to be positioned very carefully if they are to be effective. Their "capture zone" is very limited and can be severely affected by ambient air currents. Most of those that I encounter are simply not providing the extraction that the user thinks he/she is getting.

I also have two interesting pictures, courtesy of Mark Piney of HSE, of someone soldering using an extraction system with carbon filter. In the first you can quite clearly see the solder fume being blown out of the rear of the filter. The system is extracting the fume, but then putting it back into the environment!

However, in this picture the worker is soldering at the end of the PCB nearest the system. As she moves down the board, the distance ensures that the performance drops away significantly to the stage where at the end of the board closest to her (and furthest from the extraction unit) the unit is not working at all.

An alternative that I have found generally to be more effective is the downdraft bench. These move the contamination away from the worker and are less sensitive to correct positioning.

Chris

Posted By steve e ashton
I used to work for a company that used Plymovent systems extensively - for static vehicle exhaust removal and for unusual (non-standard) dusty chemical process operations. The systems seemed to work well, provided they were adequately cleaned maintained.

I have since come across several similar systems that were very clearly badly obstructed and not performing at design capacity. - I have also encountered one fan in a 'home made' system that was installed back to front and was 'blowing' rather than 'sucking'!

There are other suppliers of this type of equipment - your choice depends very heavily on your specific application. A good ventilation (design) engineer or occuaptional hygienist with appropriate experience is a good friend to cultivate if you are likely to need more than one system - it is too easy for unscrupulous suppliers to 'oversell' their products to a gullible customer.

I would acho Chris' comments that in many instances for lab work, a downdraft bench may be a more appropriate solution.
Steve