Welcome Guest! The IOSH forums are a free resource to both members and non-members. Login or register to use them

Postings made by forum users are personal opinions. IOSH is not responsible for the content or accuracy of any of the information contained in forum postings. Please carefully consider any advice you receive.



Go to last post Go to first unread
#1 Posted : 08 October 2019 15:40:03(UTC)
Rank: Forum user

Hi all,

I am hoping someone can offer some advice. We have a number of small extraction units that are attached to various occassionally used woodworking machinery. The extraction units are the type with a needle felt filter fitted above with a waste bag underneath.

Our recent 14 month statutory inspection has failed the systems due to the lack of filter efficiency data for the returned air back into the factory. I have contacted the plant manufacturer and so far drawn a blank on the required data. This type of filter is readily available from various suppliers but i am still to find anyone who can supply filters that are certified to a minimum M class of filter.

I am stuggling to believe that equipment that is clearly advertised as suitable for hardwood or mdf dust do not meet the HSE's basic requirement for the returned air data filter efficiency.

Has anyone experienced this problem or can offer any advice.



#2 Posted : 11 October 2019 13:31:10(UTC)
Rank: New forum user

Hi Gazbut,

These filters are notoriously poor to say the least. We come across them on a far to frequent basis purchased mainly due to them being cheap.

The polyester needlefelt bag style filter is marketed as suitable for wood dust but in reality it is far from suitable as the fine dust works its way through the bag filter an back into the working environment.

You will have filter suppliers say that you need to allow for the 'dust cake' to build up on the surface of the bag to improve the effiency. Again this is nonsense. When the bag deflates the 'cake' falls off and you have to start again. Where the dust particles enter into the weave of the bag material they are actually workign their way through the filter and in time will breakthrough leading to very fine often respirable dust particles being recirculated back into the working environment potentially increasing the risk of exposure to respirable dusts.

Evidence can often be seen to support this with layers of dust on high ledges and surfaces. You need to ask the question how does this dust get up on to light fittings and steel work? Well the answer is its in the air. If its in teh air then someone could breath it in. Is this controlling to As Low As Reasonably Practicable? In a word NO. Therefore there is no place for these units on saw dust.

The uild up of fine dust also leads to significant explosion risk and under the DSEAR Regs this needs to be controlled. To get a secondary explosion you need <1mm of dust on a surface. Often there is much more than this around these units.

The nature of how the dust has to travel through the fan into the filter unit means these filter units need to be suitable for ATEX Zone 21 as minimum. This is often not the case.

These types of filter units do have a place in wood workshops but they should be reserved for extracting large shavings and not fine dust.

At ILEVE we haev recently started work on a project for the HSE looking into recirculating filters and one of my colleagues on the comittee undertook research into the effectiveness of these filters and the few manufactures who responded with any data we found the data to be very poor to almost. I certainly would not recommend them.

Due to the hazardous and explosive nature of wood dust it has to be recommended that these types of units are not used.

I hope this helps.

#3 Posted : 11 October 2019 14:23:03(UTC)
Rank: Forum user

Thank you for your reply ASIMS,

Our statutory inspectors (a very large insurance company!) intimated that they have taken a leaf from the recent new welding guidance in terms of carcinogens being released back into the workplace. As such they are failing systems that in our case are cutting hardwood; softwood cutting would receive a secondary defect.

It seems that even infrequently used systems such as our automatically fail the inspection.

After talking to almost every filter bag manufacturer i am fast coming  to the conclusion that our systems are going to be redundant no-one has the required data to put this to bed.

Another option mentioned to me would be to run our own tests; i fear that this would be a complete waste of money as the feeling seems to be that none of these filters would pass!!!

The lack of available information does seem to point to LEV manufacturers of this type of equipment shirking their responsibility; after all they sepecified the systems so they should be fit for purpose?

Thousands of LEV units could be condemned.



#4 Posted : 13 October 2019 14:28:47(UTC)
Rank: Super forum user

You have many issues here.

1.LEV comes under the machinery directive.

2. Under PUWER Reg 10, it is the end users responsibility to verify that the equipment is compliant with community requirements, i.e. has been correctly CE marked.  If this is not done, then the end user is immediately in breach of PUWER Reg 10.

3. If the LEV does not capture the dusts as required, then the OEM is placing this on the market illegally, as the Machinery Directive (MD) as transposed into UK law as the Supply of Machinery Safety Regulations (SMSR), in the Essential Health and Safety Requirements (SMSR) requires that harmful emissions from machinery are controlled such that they cannot pose harm, 1.5.13.  If this is not so then the equipment has been illegally CE marked.

4. LEV is also an Annexe V machine indent 6 applies, which inks back to Regulation 4.2(c).

5. A C-Type standard exists for LEV for woodworking machinery, and if this is not followed & complied with in full, then the manufacturer cannot claim “deemed to comply” status with the MD.  Thus the machine(LEV) manufacturer will have to address each and every one of the applicable EHSR’s and demonstrate how they comply with or exceed the requirements of the harmonised standards.

As yet, I have not seen one LEV installation that is compliant with the SMSR even though they are specifically included within this legislation.

The LEV industry simply ignores this piece of law because it suits them to do so it seems.

thanks 1 user thanked paul.skyrme for this useful post.
SJP on 14/10/2019(UTC)
Users browsing this topic
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.