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LorraineCFA  
#1 Posted : 13 February 2024 12:41:11(UTC)
Rank: New forum user
LorraineCFA

Good afternoon

I am a new HSE Lead and have inherited a combustile bead blaster room, the blast media is plastic particles.  There is a metal trough where the additional media is collected into, the current process is using a metal scoop to collect the media to then place into the ensloced unit.  The metal scoop doesnt seem right in terms of risk of sparks.

Should I be ordering a plastic scoop or is there a problem woith plastic and metal scrapping together?  Also is there a specific ESD requirement for brush and dustpan??

Thanks

firesafety101  
#2 Posted : 13 February 2024 12:46:38(UTC)
Rank: Super forum user
firesafety101

I don't know the answer to your question but do know about dust and its potential to "Explode".

There have been many many instances of Dust Explosions that have raised buildings to the ground. 

You will need mechanical dust extraction with suitable container/s collecting the dust then proper disposal arrangements.

thanks 1 user thanked firesafety101 for this useful post.
LorraineCFA on 14/02/2024(UTC)
Roundtuit  
#3 Posted : 13 February 2024 16:19:28(UTC)
Rank: Super forum user
Roundtuit

Rather than having the world speculate might I suggest contacting the supplier of the media and/or unit and discussing your concerns with them. Their technical literature will provide guidance for use.

Plastic blasting pellets are likely to be quite resistant to ignition (unlike for example a fine dispersal of flour dust) so it would be unlikely a spark from a metal scoop would initiate an explosion, however you failed to advise what the media is intended to remove.

thanks 6 users thanked Roundtuit for this useful post.
LorraineCFA on 14/02/2024(UTC), peter gotch on 14/02/2024(UTC), HSSnail on 14/02/2024(UTC), LorraineCFA on 14/02/2024(UTC), peter gotch on 14/02/2024(UTC), HSSnail on 14/02/2024(UTC)
Roundtuit  
#4 Posted : 13 February 2024 16:19:28(UTC)
Rank: Super forum user
Roundtuit

Rather than having the world speculate might I suggest contacting the supplier of the media and/or unit and discussing your concerns with them. Their technical literature will provide guidance for use.

Plastic blasting pellets are likely to be quite resistant to ignition (unlike for example a fine dispersal of flour dust) so it would be unlikely a spark from a metal scoop would initiate an explosion, however you failed to advise what the media is intended to remove.

thanks 6 users thanked Roundtuit for this useful post.
LorraineCFA on 14/02/2024(UTC), peter gotch on 14/02/2024(UTC), HSSnail on 14/02/2024(UTC), LorraineCFA on 14/02/2024(UTC), peter gotch on 14/02/2024(UTC), HSSnail on 14/02/2024(UTC)
peter gotch  
#5 Posted : 14 February 2024 15:31:54(UTC)
Rank: Super forum user
peter gotch

Hi Lorraine

There is of course a difference between "combustible" and "explosible" and a spectrum of each term.

Like Roundtuit I rather doubt that this material  is likely to be as "explosible" as the scenario first reads UNLESS the beads get ground together to produce dust.

So, you need more information about the nature of the material - from supplier, which then allows a proper "DSEAR" assessment to be carried out by a suitable team - and may be that will say you haven't got much of a problem.

.....or that assessment says you DO have a problem. Then time to work out what precautions to take and simply putting an extraction system might not necessarily be part of the solution.

thanks 1 user thanked peter gotch for this useful post.
HSSnail on 14/02/2024(UTC)
HSSnail  
#6 Posted : 14 February 2024 15:45:10(UTC)
Rank: Super forum user
HSSnail

 Great advice from Peter and Round. Very dangerous and or expensive to apply guidance form one chemical to another "dust" is a very generic term. I have a team who require Respiratory Protective Equipment where we have one chap who has a beard who failed his face fit test. The manager was very upset when i made him throw away the expensive air fed mask he had bought as it had wood dust filters and we are using organic solvents, and buy one with the even more expensive one with the right filters. The company he bought the 1st one off would not take it back as it was not faulty just the wrong spec. Thank goodness i found it before he started using it! Maybe the manager will do what i asked and actualy find him teh right kit or at least consult me in what hes buying.

Ian Bell2  
#7 Posted : 15 February 2024 09:45:04(UTC)
Rank: Super forum user
Ian Bell2

Strictly you should get the dust tested for its explosive properties - there are designated standards which a material test lab will test to. However that doesn't mean your process in practice will lead to an explosive situation. You could look on the Gestis database for further information about your dust.

As well as having explosive properties the other factor to consider is the dust paricle size. Dusts larger than 0.5mm in size are not explosive - British Standard BS60079-10-2 Explosive dust atmospheres has a cut off at 0.5mm particle size.

Thats does NOT mean the dusts aren't combustible - which should be considered under your normal fire risk assessment.

For a dust /process to be explosive that ALL 5 criteria below must be satisfied at the same time

- the dust is explosive

- the must have a particle size that will explode

- the dust is at an explosive concentration in air

- the air has sufficient oxygen concentration

- there must be an ignition source present

As a rule of thumb guide, for a dust cloud to be explosive, the concentration will be such that it will be difficult to see through the dust cloud. A dust cloud explosive concentration is typically quoted as 20-30g/m^3

For comparision occupational health exposure limits are down around the mg level

Ref Dust Explosion Prevention and Protection A Practical Guide - John Barton ISBN 0852954107

Any further DSEAR questions, drop me a message, DSEAR is what I do.

thanks 3 users thanked Ian Bell2 for this useful post.
A Kurdziel on 15/02/2024(UTC), peter gotch on 15/02/2024(UTC), Lee45403 on 23/02/2024(UTC)
John Elder  
#8 Posted : 16 February 2024 14:14:50(UTC)
Rank: Forum user
John Elder

Lorranine

I hope you are well.

It is not the plastic beads that are the problem it is the substance being blasted/removed/keyed in preparation for another process or removing paint or such like. I have assessed multiple grit, metal, plastic bead blasting processes and as yet have never had to classify one as having an explosion hazard or DSEAR Hazardous area.

You have been given some good practical advice I noticed. Ian is correct in what he has stated and providing you also don’t have layers a few millimetres deep of dust from the substance that can be lifted up accidently into the air to form a dust cloud then it appears you will not have an explosion risk.

Metal is sometimes used for the scoop as it is electrically conductive and is normally attached to a grounding lead to prevent static discharge. Brass copper or bronze are commonly used as they are non-sparking.

peter gotch  
#9 Posted : 16 February 2024 15:23:43(UTC)
Rank: Super forum user
peter gotch

Hi Lorraine

A PS to what John has written.

Devastating dust explosions rarely happen due to the initial combustion but rather where that creates a pressure wave that disturbs the potentially explosible dust that has settled on surfaces - these are then ignited in a "secondary dust explosion".

So, one of the various things which should be done is to house processes which generate explosible dust is to design buildings etc to minimise the existence of any ledges on which dust can settle.

Which still leaves floors and the flat or flattish surfaces of equipment - so then consideration of extraction to capture what is emitted and/or a very high standard of cleaning.

Don't forget to record all you have learned from this thread on your CPD record!!

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