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.

Notification

Icon
Error

Options
Go to last post Go to first unread
Climhazard  
#1 Posted : 20 February 2020 12:02:02(UTC)
Rank: Forum user
Climhazard

Hi all,

My company is looking into alternative methods of degreasing metallic parts following various NDT inspections (to remove oils, contaminants, fluorescent and magnetic penetrants etc). We currently use 2 large industrial degreasers which use perchloroethyelene, however we are aiming to replace one of these due to it's age and therefore environmental impact.

A suggestion has been made to replace the largest degreaser with a new, smaller unit which would eliminate the environmental impact of perchloroethyelene. The suggestion is to introduce 2x acetone wash stations in a nearby room.

We're still figuring out what exactly the system would look like but in general: 2x Wash stations with internal storage for around 30L acetone. Acetone will be pumped from storage container using a compressed air pump and through a spray gun. The acetone will wash over the part and flow back into the storage container. A filter will be place either before the spray gun and on return to the storage container.

Issues and controls I forsee: Potential for explosions or fire - Ensure all equipment is earthed. Switches and lights are intrinsicly safe.  Static electricity - Could use some advice on this as we'll be pouring acetone to fill the storage container and using a spray gun. Vapour build up above the liquid solvent in the storage container - Could this be an issue? Exposure - There is an extraction system in place in the suggested room, but this would be modified by a suitable contractor for use with acetone. Hood sizes may be an issue because of the large sie of the baths. Weight - The shafts weight upwards of 150kg but weight ratings will be built into the structure of the stations.

We're working through all of the possible issues, even if that means the end results is not proceeding with the idea.

Any thoughts and questions are more than welcome! 

Hsquared14  
#2 Posted : 20 February 2020 12:17:38(UTC)
Rank: Super forum user
Hsquared14

I've seen some units being used in automotive and aerospace parts manufacturers which use a water based emulsion to remove the grease and other debris.  I don't recall what the chemicals in the emulsion were but I'm pretty sure that citrus extracts played a part and the resulting grease was skimmed off the top of the water by an automatic weir system and treated to produce a solid residue.  Might be worth looking at?

Climhazard  
#3 Posted : 20 February 2020 12:32:49(UTC)
Rank: Forum user
Climhazard

Originally Posted by: Hsquared14 Go to Quoted Post

I've seen some units being used in automotive and aerospace parts manufacturers which use a water based emulsion to remove the grease and other debris.  I don't recall what the chemicals in the emulsion were but I'm pretty sure that citrus extracts played a part and the resulting grease was skimmed off the top of the water by an automatic weir system and treated to produce a solid residue.  Might be worth looking at?

Thanks for the suggestion. We've used aqueous washing in the past, but due to strict cleaning specifications we're unable to use anything water or detergent based, so solvents are our only option.

Ian Bell2  
#4 Posted : 20 February 2020 13:02:31(UTC)
Rank: Super forum user
Ian Bell2

You need to complete a risk assessment under the Dangerous Substances and Explosives Atmospheres Regulations (DSEAR) HSE Acop L138.

From that you will be able to determine the ATEX rating of electrical equipment, the extents of any hazardous areas generated, if you do put electrical equipment inside a hazardous area the required rating e.g IIA T1 Cat 1/2/3 depending on the hazard zone assessment.

I shudder at your comments about getting a contractor to modify the existing extraction without further analysis... acetone is quite volatile.

As part of your assessment you should complete an ignition assessment as well and consequence assessment.

Also develop your emergency procedures for the plant.

Happy to help

 

Climhazard  
#5 Posted : 20 February 2020 13:43:22(UTC)
Rank: Forum user
Climhazard

Originally Posted by: Ian Bell2 Go to Quoted Post

You need to complete a risk assessment under the Dangerous Substances and Explosives Atmospheres Regulations (DSEAR) HSE Acop L138.

From that you will be able to determine the ATEX rating of electrical equipment, the extents of any hazardous areas generated, if you do put electrical equipment inside a hazardous area the required rating e.g IIA T1 Cat 1/2/3 depending on the hazard zone assessment.

I shudder at your comments about getting a contractor to modify the existing extraction without further analysis... acetone is quite volatile.

As part of your assessment you should complete an ignition assessment as well and consequence assessment.

Also develop your emergency procedures for the plant.

Happy to help

Great advice, thank you.

As for modifying the current LEV, we wouldn't carry out any changes until we know exactly what the process is going to be. What that final process actually is is changing regularly.

chris.packham  
#6 Posted : 20 February 2020 14:41:53(UTC)
Rank: Super forum user
chris.packham

You mention a spray gun. Will this be hand held? If so how will you protect the operator? Simply providing PPE might not be compliant with the requirements of COSHH and PPE regulations.

Climhazard  
#7 Posted : 20 February 2020 14:46:47(UTC)
Rank: Forum user
Climhazard

Originally Posted by: chris.packham Go to Quoted Post

You mention a spray gun. Will this be hand held? If so how will you protect the operator? Simply providing PPE might not be compliant with the requirements of COSHH and PPE regulations.

It will be hand-held, although we're not sure what pressure it will operate at. There's a chance that it will only need to gently flow over the part to degrease it, in which case the risk of splashes will be low. ​​​​​​​An interesting point though, thanks.

Climhazard  
#8 Posted : 20 February 2020 14:55:10(UTC)
Rank: Forum user
Climhazard

Originally Posted by: chris.packham Go to Quoted Post

You mention a spray gun. Will this be hand held? If so how will you protect the operator? Simply providing PPE might not be compliant with the requirements of COSHH and PPE regulations.

It will be hand-held, although we're not sure what pressure it will operate at. There's a chance that it will only need to gently flow over the part to degrease it, in which case the risk of splashes will be low. An interesting point though, thanks.

JohnW  
#9 Posted : 20 February 2020 16:42:41(UTC)
Rank: Super forum user
JohnW

Acetone is highly flammable and any process will be a significant fire risk, it evaporates quickly at room temperature so any leak will present a spark-ignition hazard and a respiratory/ nausea hazard to employees I have precision engineer clients who use a Dowclene 1601 process, a fully-contained high temperature process (160degC) special equipment e.g. Amsonic. Expensive but ensures the quality required by the aerospace industry. John

Edited by user 20 February 2020 16:44:45(UTC)  | Reason: Typo

JohnW  
#10 Posted : 20 February 2020 16:53:07(UTC)
Rank: Super forum user
JohnW

Another equipment supplier for the Dowclene 1601 process is Ecoclean GMBH John
Climhazard  
#11 Posted : 20 February 2020 16:53:08(UTC)
Rank: Forum user
Climhazard

Originally Posted by: JohnW Go to Quoted Post
Acetone is highly flammable and any process will be a significant fire risk, it evaporates quickly at room temperature so any leak will present a spark-ignition hazard and a respiratory/ nausea hazard to employees I have precision engineer clients who use a Dowclene 1601 process, a fully-contained high temperature process (160degC) special equipment e.g. Amsonic. Expensive but ensures the quality required by the aerospace industry. John

A don't have access to the MSDS' at the moment but if I'm not mistaken that's the modified alcohol option?

This is the alternative we've been looking into, however the investment would be around £250k, which isn't easy to get authorised.

JohnW  
#12 Posted : 20 February 2020 17:02:12(UTC)
Rank: Super forum user
JohnW

Yes the equipment is expensive but is enclosed, high temperature, low risk as there’s not much for operator to do except when the solvent needs replacing - I think the contractor service does that, here is link to SDS. For COSHH the risks are low but remember the equipment process temperature is 165degC to boil the Dowclene http://www.efkimya.com/pdf/dowclene_msds_1601.pdf

Edited by user 20 February 2020 17:04:02(UTC)  | Reason: Typo

Hsquared14  
#13 Posted : 21 February 2020 12:20:24(UTC)
Rank: Super forum user
Hsquared14

Originally Posted by: Climhazard Go to Quoted Post
Originally Posted by: Hsquared14 Go to Quoted Post

I've seen some units being used in automotive and aerospace parts manufacturers which use a water based emulsion to remove the grease and other debris.  I don't recall what the chemicals in the emulsion were but I'm pretty sure that citrus extracts played a part and the resulting grease was skimmed off the top of the water by an automatic weir system and treated to produce a solid residue.  Might be worth looking at?

Thanks for the suggestion. We've used aqueous washing in the past, but due to strict cleaning specifications we're unable to use anything water or detergent based, so solvents are our only option.

I have seen aqueous units in use for aerospace applications and in particular for parts used in satellites - cleaning specifications don't get stricter than that and they were the preferred cleaning method specified by the customer.  No detergents were involved and there was zero residue on the finished article. 

Holliday42333  
#14 Posted : 21 February 2020 13:13:31(UTC)
Rank: Super forum user
Holliday42333

I have no experience of these types of degreasers when using acetone, but based on a a previous lab based life I'd agree that you would be surprised how volatile acetone is.

That 30l is going to disappear up your LEV pretty darn quickly, particularly if you end up spraying, and if it doesn't go up the LEV you might find your operator on the floor in a stupour before you know it.  The lab I used to work in (a long time ago) used acetone to clean the work benches.  A 200ml squirt bottle would evaporate in less than a minute if sprayed over the bench surface and everyone within the room would be feeling woosy fairly soon after that.  Thats before you factor in how flammable it can be.

OK, you are reducing your risk, but are you reducing it by much?  You could be introducing other risks too.

The modern aqueous units do seem to offer some kind of black magic in degreasing terms and would be far easier to manage in SHE terms, it would appear.

chris.packham  
#15 Posted : 21 February 2020 14:13:32(UTC)
Rank: Super forum user
chris.packham

I have recently visited a workplace where degergent based degreasing was used on safety critical aerospace components. For me one major benefit of this approach is that it is far easier to provide adequate PPE than it is for a solvent such as acetone. 

Given the emphasis on LEV as has been stated, you will lose much of the acetone in the extraction system. What recovery system will you have as I cannot imagine that you will be considering discharging the acetone laden air into the general atmosphere? What will you do then with the recovered acetone? 

Climhazard  
#16 Posted : 24 February 2020 09:09:16(UTC)
Rank: Forum user
Climhazard

Thanks everyone, we have another meeting on this today so I will pass along what I've learned.

My feeling is that this is a no go.

A Kurdziel  
#17 Posted : 24 February 2020 09:17:41(UTC)
Rank: Super forum user
A Kurdziel

Humbrol Airfix used to make paints for model airplanes. They used to have a factory on Hedon Road, Marfleet in Hull. I say used to, because in 1989 they had a spill of acetone. Some genius was moving a drum of the stuff around the site on a fork lift. It was, of course, unsecured and it fell off the forks and the entire contents spilt on the floor. Somebody then decided that two YTS trainees (remember those?) aged 17 and 18, should mop it up, using clothes etc. They could not see the extent of the spill so they turned on the lights. There was an explosion and one trainee (the 17 year old) was killed and the other had what we now call, life changing injures(https://www.itv.com/news/calendar/2018-07-06/nhs-70-a-lasting-bond1/) I can’t remember the fine but it probably ran into hundreds of pounds.( yes the good old days) .

Acetone is very volatile and highly flammable. If it is allowed to form an aerosol it becomes explosive. This is why people on this forum are so nervous about using it as in any sort of spray. Is it really the only solution or is it just something that a particular client is fixated on?

fairlieg  
#18 Posted : 24 February 2020 09:24:05(UTC)
Rank: Forum user
fairlieg

Originally Posted by: A Kurdziel Go to Quoted Post

....Some genius was moving a drum of the stuff around the site on a fork lift.....

I know you didn't mean that!
A Kurdziel  
#19 Posted : 24 February 2020 11:35:54(UTC)
Rank: Super forum user
A Kurdziel

Originally Posted by: fairlieg Go to Quoted Post
Originally Posted by: A Kurdziel Go to Quoted Post

....Some genius was moving a drum of the stuff around the site on a fork lift.....

I know you didn't mean that!

One or both of us is being sarcastic! 

Climhazard  
#20 Posted : 28 February 2020 14:25:23(UTC)
Rank: Forum user
Climhazard

A quick update for those of you interested. 

We are now going ahead with the acetone wash stations based on the fact that it would be extremely difficult to control every potential ignition source in and around the area. Also based on the fact that we'd lose a large amount of acetone to atmosphere (extracted).

JohnW  
#21 Posted : 28 February 2020 16:14:24(UTC)
Rank: Super forum user
JohnW

Originally Posted by: Climhazard Go to Quoted Post
A quick update for those of you interested.We are now going ahead with the acetone wash stations based on the fact that it would be extremely difficult to control every potential ignition source in ... .
You can edit your message, I think you meant “We are NOT going ahead.....“ :o) John

Edited by user 28 February 2020 16:15:49(UTC)  | Reason: Typo

Climhazard  
#22 Posted : 28 February 2020 16:17:28(UTC)
Rank: Forum user
Climhazard

Originally Posted by: JohnW Go to Quoted Post
Originally Posted by: Climhazard Go to Quoted Post
A quick update for those of you interested.We are now going ahead with the acetone wash stations based on the fact that it would be extremely difficult to control every potential ignition source in ... .

You can edit your message, I think you meant “We are NOT going ahead.....“ :o) John

Indeed I did, that message makes me sound SUPER irresponsible!

I can't edit the post sadly...

thanks 1 user thanked Climhazard for this useful post.
A Kurdziel on 28/02/2020(UTC)
Ian Bell2  
#23 Posted : 28 February 2020 16:57:05(UTC)
Rank: Super forum user
Ian Bell2

Just use correctly rated DSEAR/ATEX rated equipment Group 2 IIA T1 Cat 1/2/3 depending on Ga/Gb/Gc protection following your hazardous area classification study.

JohnW  
#24 Posted : 28 February 2020 18:56:13(UTC)
Rank: Super forum user
JohnW

If the enclosed Dowclene process/equipment is used then hazards and ATEX are avoided.

Edited by user 28 February 2020 18:57:14(UTC)  | Reason: Typo

Ian Bell2  
#25 Posted : 29 February 2020 01:16:04(UTC)
Rank: Super forum user
Ian Bell2

No sense of adventure,

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.