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Posted By Tracey C
I am putting together a risk assessment and method statement for the cleaning of drains we have on one of our sites, the building was built in the 1800's and as we are putting new showers and kitchens in we are having a problem unblocking the drains. We have been using a non hazardous substance but it does not seem to be doing the trick so our FM guy has come up with this other chemical that is a Sulphuric acid based drain cleaner. I have the safety data sheet but not sure how long these guys should be exposed to this stuff. The OES is 0.3 mg/m3 can anybody guide me as to how you work out the WEL's.
Many thanks
T
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Posted By Paul Leadbetter
Tracey
Sulphuric acid doesn't have a WEL but, in any case, it would only be relevant if the acid was to become airborne. Check the MSDS for the substance and make sure people wear the appropriate PPE.
Paul
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Posted By Tracey C
Many thanks Paul I have taken note of the PPE Butyl rubber gloves and face shield. Other protective clothing to prevent skin contact.
With regards to the respiratory equipment it states none needed except if the general level exceeds the recommended occupational exposure limit but it does not say what the recommended exposure limit is.
These data sheets are not that easy to read sometimes are they? Or maybe it is just me, i did bang my head this morning getting into the car!!
Thanks for the help
T
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Posted By Paul Leadbetter
Tracey
You're right; MSDSs can be difficult to understand. I think the writers sometimes expect the readers to be as scientifically literate as they are; I think that MSDSs should be written in plain English.
Paul
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Posted By W.H.FLEWITT
Tracey,
Beware acids in drains you may find Hydrogen Sulphide released in significant quantity.
In November 1991 Three men died at Watney Market after using acid. Rodding is an old and often very effective way of dealing with the problem.
Regards
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Posted By garyh
I would say that you need to do a Risk Assessment / COSHH assessment, call it what you will. However.........
I was once an effluent manager; we NEVER unblocked drains using chemicals, only mechanically. You do not know what chemical reactions you can unleash (eg - Bleach + acid can evolve Chlorine gas).
In addition, how do you know that your drains are constructed of material that will resist the acid? Will it damage or even dissolve them?
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Posted By Paul Oliver
Your barking up the wrong tree I think.
You have already identified the main problem so why not put an action plan together to sort it out: replace or modify the drainage system.
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Posted By TBC
Good response grayh - Sulphuric acid can be dodgy stuff. Gases and possibly explosive atmospheres come to mind.
Take great care.
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Posted By GJB Davis
Tracey,
One other risk you may need to consider with a sulphuric acid (H2 SO4) based drain cleaner is 'blow backs'.
Chemical reactions has already been identified but if the H2 SO4 content is above say 40% it can react (sometimes quite violently) with water, that could be contained in the drains e.g. as part of a blockage, creating a lot heat (exothermic reaction). The resulting reactant can then be forced back up the drain if the blockage is too thick to be instantly dispersed. Hot sulphuric acid solution 'erupting' (sorry for the dramatic word, couldn't think of another one) is not something you would want to be in the way of.
Our company used to sell this type of product many years ago until a client's employee received a chemical burn due to the above.
regards
Giles
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Posted By Robert K Lewis
Tracy
Without knowing the construction of your drains you really should not be shoving any chemicals down them. The drains ought to be exposed and replaced as part of the refurbishment - it may even be that you have a collapsed drain and you will simply be putting chemicals into the environment. Any plumber coming up with this solution really needs to be checked out for competency as per regulation 4 of CDM 07, which is applicable to both non-notifiable and notifiable work.
Bob
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Posted By Tracey C
Thanks for all your responses. Paul i would love to re-look at the drainage system but apparently the unblocking is required only in the shower traps as there were several reports last year of blocked shower drains. The refurbishment is being undertaken on 1000 showers and bedrooms and there is no budget or time to carry out any other works. My concern was also that if the builders start using all sorts of chemcials down the drains we would end up having a big flood due to chemicals causing corrosion.
I have taken on board all the comments many thanks and i am looking at other safer posibilities. Could somebody give me more information on the Watney Market incident in November 1991 can't seem to find anything about it?
Cheers
T
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Posted By TomP
Haven't got the details for that one but can report a personal incident.
About two years ago I 'happened' to be going to the loo and discovered two contractors in there coughing their lungs up in a cloud of vapour...
Got them out luckliy...but had I been a few seconds later........
They had poured sulfuric acid onto the chlorine bleech blocks and nearly killed themselves. Best guess was cyanide gas but regardless of the gas it meant they were deselected as a competent supplier.
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Posted By CFT
Its a product that does do what it states on the cannister; it is usually at 92-96% pure SA,and often in 1 litre 2 litre and 5 litre containers, around twice the weight of water; I would never ever recommend anyone to use this product without proper training, it can be a beast, the opaque smoke you will get from it is foul and does smell similar to rotten eggs, where its reaction with water occurs it is absolutely not practical for inside blockages, you cant usually vent the fumes. It does not mix well with other chemicals particularly Chlorine, Hydrogen Peroxide & Sodium Hydroxide among others.
It works fairly well in a decent dosage and believe it or not it is biodegradable.
Personally I would never permit anyone to use the stuff and the quicker it is available under license only the better. The cheapest and most successful cure would be to use the services of a professional HPJ unit set low to start with, a pencil or cutting jet with backwards facing to pull out debris, this saves a potential blockage further along. These units with a built on bowser usually run up to 3000psi and will remove root infestation and cut through a house brick.
Give it a go before digging up the area for replacement; final word is leave the 'Drain Clear' alone.
CFT
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Posted By John_Webster
I have a (now empty ) bottle of Sulphuric acid drain unblocker which I use as one of my "props" during CoSHH training. It came to me via our Casualty Dept, who were asking about its disposal. When I enquired how they came by it I was told that it had accompanied a casualty who was brought in with chemical burns and had the presence of mind to bring the bottle to identify the substance that had caused his injuries.
As a former chemist I was horrified to find that conc. sulphuric acid was used for this purpose. The dangers, well expressed by others above, are all too real, and the risk of a disfiguring injury or life threatening situation (when you can smell the bad eggs, the H2S is already at toxic levels. When you can no longer smell it, the concentration may have actually increased) make this one of those applications where safer alternatives must always be tried first - and thats CoSHH regs as well as common sense. If the main problem is shower traps and the like, if they cannot be physically opened, rodded or jetted there are powerful enzymatic cleaners which should do the trick. Failing that, I would prefer strong caustic soda to H2SO4, remembering not to use the undissolved solid if the drains are plastic.
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Posted By ciara brennan Hi all i agree with all the previous posts about this product and i thought you guys might be interested to know you can actually buy the stuff from B&Q under the name "one-Shot" I used it once to unblock drains in my flat!! http://www.diy.com/diy/j...e+shot&selected=products
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Posted By Colin Puddy
Tracey,
All this talk of using chemicals is worrying, a reasonable sized drainage specialist company should have a piece of kit called a sewer rooter which is a mechanically driven clearance tool that can deal with most blocked drains by use of various cutters. These are available in differing sizes/power why not give that a try before risking chemicals in a drain that is over 100 years old and blocked with who knows what.
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Posted By Robert K Lewis
If it is only the shower traps then replace them - it is going to be far more cost effective and safer than playing around with drain acid. If the problem still persists then your budgets are going to need a review.
This sounds suspiciously like a mill refurbishment or similar into multiple occupation. You need to get the drainage drawings and get your M&E consultants to work out the issues involved. If you do not have them available then one must ask why not - they should have been in the H&S file since 1994. I rather suspect this refurbishment postdates this time point.
Bob
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Posted By Angela Oakey-Jones Hi Tracey, I'm not a chemicals expert but I find the internationally recognised chemical safety cards on the NIOSH website really helpful. They're clearly written in English so you can understand what's needed. They're arranged in alphabetical order and easy to search. You might like to take a look at http://www.ilo.org/publi...sht/_icsc03/icsc0362.htm for the safety card on sulphuric acid 100%. There are many others related to sulphuric acid (and, being an American index, it's spelt with an "f" not a "ph"). CAS numbers are also quoted, so it may be easier to search on that. Hope this helps Angela
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Posted By Tracey C
I would just like to say a big thank you to all of you that took time to help me out. You have all given me a lot to think about.
Just to let you know i stopped the job yesterday and have a meeting with the refurbishment team tomorrow to find a safer system of work.
Fondest
Tx
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Posted By Robert K Lewis
Tracy
Hope this is not needed for October.
These types of blockage can be difficult to trace and actually may simply be a single location causing the whole stream to block up. Get your plumber to look at the last trap in the line before you go too far. It may also be that you need to improve the drain filter to prevent foreign objects gaining access. I will not mention what I have found in these locations:-)
Bob
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