As wood dust (along with many other dusts) is combustible, I assume a DSEAR assessment has already been undertaken ?  If so, the airborne concentrations associated with these tasks should be known, and that should determine whether or not an ATEX rated vacuum cleaner is required.

However, from what you've said already (ie that the housekeeping for dust fines is poor, dry brushing takes place and "making a mess when emptying LEV" leads me to believe it would be a good idea.

Maybe suggest to them that they consider the cost of an ATEX rated vacuum against the potential total loss of the building (and possibly lives) if they choose to buy a Henry and it DOES ignite a dust cloud ?

There again, their luck might just continue to hold...

I don't think you can be sure that there won't be an explosive atmosphere in the workshop.  Check out the website below.

https://www.nilfisk.com/en-gb/products/Pages/Vacuum-cleaners/Industrial-vacuum-cleaners/group.aspx

Thanks for the input.

There is LEV in the area which is subject to insurance inspections etc.. Within the enclosed area of the LEV system such as the flexible ducts /bag filters and manifold this would be a Zone 20 and the basis for safety is within the design of the LEV.

The only reason a dust cloud could occur is when the operators are changing the full dust bags from the LEV system and an open bag was accidentally knocked over, this creating a potential dust cloud.

Or if the LEV had a catastrophic failure/ ducts blew off and started pumping wood dust into the workshop etc.. ( inspected 6 monthly by a well-known insurance firm)

Under normal circumstances there can be no reason for an explosive atmosphere to exist within the workshop.

All I am trying to get me head around is whether we can vacuum up housekeeping to stay on top of  wood dust without using a ATEX rated vacuum cleaner. Loads of products on line for vacuuming up timber dust that are not ATEX rated.

I guess what I am confused with is the following;

Is it the product that you are vacuuming up (wood dust) that determines whether you need an ATEX vacuum, or is it the atmosphere that you are vacuuming in that dictates whether it is an atex rated vacuum.

 Thanks

Some guidance here, if correct - 420microns & less than 33% moisture content

http://www.coastforest.org/wp-content/uploads/2013/12/dust_literature_review.pdf

Firstly there should not be a problem with wood dust, if there is the LEV is inadequate, regardless of whether it is tested or not bye anyone.

Remember inadequate can also mean not used correctly.

There should never be a risk of explosion in a wood working workshop as the LEV should be adequate to control any dust, also the LEV is machinery under the SMSR, and thus must be designed, manufactured and installed such that it cannot pose an explosion hazard.

Absolute requirement from the EHSR's of the SMSR.

If you are collecting wood dust after spillages use the LEV system, get pick up points fitted smaller diameter flexible lines with blast gates that can be opened to allow the waste to be sucked into the LEV.

As far as the changing of bags goes, then that is a discipline thing and they shouldn't really be allowed into a scenario where they can be knocked over?

Do a Risk Assessment, bag being knocked over creating a dust cloud which can reach an ignition source which is present at that point in time, and has sufficient energy to ignite the dust could.  For a start EAWR pretty much requires compliance with BS 7671 which requires a 300mA RCD on pretty much all circuits in a woodworking facility.  Then there is the I&T and maintenance requirements of BS 7671, PUWER & EAWR to consider.

What is the likelihood of occurrence in the workshop?

If you do the cleaning up with the LEV then you eliminate the vacuum.

Solved.

Edited by user 13 July 2018 17:53:05(UTC)  | Reason: Spelling

Is damping down the spilled dust and simply brushing up not a simpler option - and ultimately less expensive, even if a bit more labour intensive?

Not all woodwork is the same... The OP is not talking about fine joinery / furniture work on kiln dried hardwoods being finished to a fine surface.... Pallets are generally made from softwood that has NOT been kiln dried... (may have been air dried - so maybe not green timber at 35% moisture, but generally 25% or thereabouts depending on local weather...). Slats are cut with a saw with reasonably coarse pitch... and not finished with a thicknesser/planer or sanding belt ... It is EXTREMELY unlikely that the initial operation will produce an explosible dust. The wood waste is not explosible dust since it is not in the particle size range that will explode (witness how close to the machine the vast majority settles for some indication of aerodynamic diameter).  The (very small proportion of) material produced that IS fine enough to spread any distance will normally be high moisture content - and hence even it will not readily explode (when it is produced).  There's ample literature available on this subject but many (in HSE and elsewhere) still seem to believe that expensive lab tests are necessary for every specific case... Please, do not assume that all wood waste is explosible fine dust.  It isn't.  There have been several major sawmill explosions over the years but these have generally been attributed to secondary explosions when accumulated waste on rafters and other elevated horizontal surfaces has been disturbed by an initial turbulent event (fire/small explosion)  It is very important to keep horizontal surfaces clear of significant accumulations, since these will dry further over time, and the risk of ignition / explosion increases from the material initially produced.  Provided your housekeeping is good, there should be little (if any) chance of explosion in this type of facility.  I have seen lab test results reporting that a sample sent for testing was explosible - closer reading suggested they had oven dried the sample for three days before testing, been unable to get it to explode, so sieved it to remove the coarse particles that were preventing the explosion.  So a tiny proportion of the sample - after removal of a large amount of water - could (with difficulty) be made to explode.... Therefore the sample was reported as explosible dust... And the sampling itself had already skewed the process by only taking bulk sweepings from horizontal surfaces some distance from the saw.....  This kind of quasi 'science' helps no-one. Sorry for the rant folks!

I would question whether you have a significant risk of an explosion.

Key parameters are particle size and moisture contents.

Remember the risk of an explosion theory modifies the traditional fire triangle of

1. Ignition source

2. Oxygen

3. Fuel present to burn

to

1-3 as above

4 Confinement of the dust

5 Dispersion of the dust in air

In a recent thread on weld fume a kind poster (Alan.J I think) at #24 has a link to a HSe doc and in the section before weld fume it also talks about wood dust. perhaps worth a read. there isw an expection of the HSE shown in the little chart.

link to thread

http://forum.iosh.co.uk/posts/t127992-HSE-changes-to-welding-risks

Chris

Sometimes the easiest solution is to have a flexible duct fitted to a specific low level section of ducting on the LEV system controlled by a manual damper. The LEV system then is effectively used to vacuum up the spilt dust upon completion of the emptying operation. I have these installed as a standard when fitting out woodworking shops