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Posted By RBW100
Hello all,
This is my first post here and I have recently joined IOSH and am hoping to achieve TechIOSH grade.
Any way down to business. I am the engineering manager at a frozen food company and am also responsible for Health and safety. I was interested by an earlier thread regarding engineering works in spiral freezers. I have spirals in operation and need to gain access for engineering work. These freezers are normally cold (you don't say!) at around -35 deg. C when entering for breakdowns. They contain machinery that can be started outside of the freezer. The refrigerant used is ammonia, which is contained within stainless steel pipework. Access is via a full size door, there is another door but from the inside you'd need to access it by climbing over the belt and other machinery.
I am currently developing a safe system of work for access to the freezers for breakdowns, i.e. when the unit is cold. My thoughts are that the equipment needs to be designated as a confined space because of the foreseeable risk of an ammonia leak; machinery being started from outside; the extreme temperature and the access as described above.
I suppose my question is do people agree that it sounds like a confined space, and does anyone out there have a system of work that covers this type of thing that I could look at to help me formulate mine?
Kind regards,
Rob W
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Posted By Paul Oliver
Confined Space:
"Any enclosed area with only one entrance, and/or where hazardous vapour, dust or fumes may accumulate, and/or where oxygen may be deficient".
"Any space that is large enough and so configured that an employee can bodily enter and perform assigned work, has limited or restricted means for entry or exit, and is not designed for continuous employee occupancy".
I would agree that you could classify this area as a confined space and so now you need to assess it accordingly, to ensure any access is suitbaly controlled with work in this area properly managed so as to avoid injury to any persons woroking in this location.
:-) Paul
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Posted By Schui
Rob
you should have a Lock out Tag out system in operation as to prevent accidental start up from the outside when the work is being carried out inside
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Posted By Les Welling
Under the Confined Space Reg 1997 a "confined Space" has two defining features. Firstly, it is a place which is substantially (though not always entirely) enclosed and, secondly, there will be a reasonably foreseeable risk of serious injury fro hazardous substances or conditions in the space or nearby.
Risks can arise from:
Lack of oxygen
poisonous gas, fumes or vapour etc
so I would say that you should class it a a confined space.
In addition, I would expect it to be classed as a "High risk confined space" I think.
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Posted By RBW100
Thanks for the advice so far!
Does anyone have an example of a safe syetm of work for entry into a spiral freezer that they could let me have a look at?
Also a point of interest; I have seen spiral freezer installations at several food factories both in the UK and in the rest of europe, none of which were designated as confined spaces. A bit of an over sight I think!
Rob
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Posted By Helen C
The enclosed nature of the space and the potential for there to be ammonia present would certainly suggest it is a confined space.
The size, low temperatures and general awkwardness for access don't in themselves mean that the area is confined space but as you rightly suggested they are hazards the need to be addressed.
I do not have a SSoW for entry into a spiral freezer but can give you some pointers for designing a SSoW for yourself.
If you're still stuck - give me a call at CSTS (Confined Spaces Training Services) 01925 244144.
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Posted By peter gotch
Rob.
Definitely a confined space, albeit with probably less risk of significant leak than in bulk storage as most minor leaks will simply freeze onto pipework.
History of fatalities in indoor bulk ammonia installations, and similarly carbon dioxide installations [in e.g. soft drinks factories].
Regards, Peter
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Posted By Merv Newman
In line with schui, in addition to the confined space issues, those inside the space must have total mastery of any equipment which could be started by someone outside.
Without going into full details (I can if you make it worth my while) each individual must verify that all potential sources of energy are isolated and locked off. This is typically done by attaching a padlock to the energy source, (keeping the UNIQUE key in your pocket) and verifying that the equipment cannot now be started.
Each person going in does their own lock and try.
Merv
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Posted By RBW100 Hi Merv, I would agree that a lock and tag procedure would appear to be the most obvious way to ensure that the machine was not started from the outside, but there are some problems with that approach. The main one is that the need to enter the freezer in the first place is generally because the belt has come off its runners or something similar. In order to get the belt back on it needs to be run in reverse and somtimes in a forward direction after the engineers have made adjustemnts to the belt etc. This is done with the engineers in the freezer so that they stop the belt if it appears to be catching on something. This is achieved in one (the most modern) of the freezers by the use of a 'service handle'. Removing the handle from this holster inhibits the controls of the main panel and gives the user of the handle the ability to run the belt by holding down two buttons on the handle at the same time. The manual for the freezer states that 'The man holding the handle takes responsibility for ensureing that all other in the freezer and free of the belt when he start it'. I think the service handle is a good device as it means that the chance of external start is eliminated and I'm investigating having it retro fitted to the two other freezers. As for the ammonia, it can be detected by the nose at low level (25 -50ppm) and I thought of putting into the SSOW that the freezer should be evacuated if such a smell was detected. Do other see this as sufficent? Most of what I have read on ammonia detection is related to detection of explosive atmosphere concentation (say 3000ppm+) which would suggest relying on the human nose is acceptable. Finally I have to work out how to get someone from the mezzanine in teh freezer out if they broke a leg. The mezzanine is accessed by a fixed ladder which provides access via a trap door that is around 3ft sq. Would expect the provision of a hoist of some kind is required? Thanks all, Rob PS The type of freezer I'm on about is this one: http://www.fmctechnologi...MPACTMSeriesFreezer.aspxthe pdf shows some of the internals: http://www.fmctechnologi...m/upload/gcmbrochure.pdf
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Posted By Merv Newman
Rob,
two points.
First on ammonia detection by smell. in real life people will smell a whiff of ammonia and ignore it. "It's not much" After a while the sense of smell becomes desensitised and much higher levels are tolerated. Eventually it becomes too much. You need some method of continually monitoring ammonia levels and a "get out of there" threshold.
Second, on control of energy sources. The situation you describe is quite common, similar, say, to a tool-setter setting up a press. All "normal" (i.e. production situation) controls are off and he needs to make the machine move. Written procedures and training exist to cover this kind of situation.
However, combine this with a "confined space" and you have to go a step further. Again, it is not an unknown situation.
Should it happen that you need to energise the conveyor while people are in the vicinity (is it REALLY necessary ?) then the person in charge of the controls is a SENIOR manager. Not a mate. Not the maintenance foreman. Certainly NOT the area production manager.
You need someone who could be done for being the "controlling mind" and go to jail if they kill someone. RH, Accounts, Finance, Legal, Marketing ? Doesn't matter for me. So long as they know what to do, how to do it, and know what will happen if they get it wrong.
I want that person to be sweating before they push the button.
There's nasty.
Merv
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Posted By RBW100 Hi Merv, Thanks for the input. My basis for ammonia detection by nose is from the following HSE advice for LA inspectors http://www.hse.gov.uk/LAU/LACS/31-1.htm, which talks about the use of human detection in the context of plant rooms. Although the unit I'm talking about is confined, there is never a smell of ammonia present in there, hence a leak would be clearly identified and not treated as the norm. Also we have very good control of our ammonia plant, compared with many I have visited. Some plant rooms I could not bear the smell of ammonia, when the engineer concerned was adamant (stand and deliver?) that there were no leaks. On the use of the service handle (remote control), I suppose that it depends on your definition of senior manager. Much of the time there is no senior manager on site as production runs to midnight. There is a site production manager on site all the time who has general responsibility for all the site, but is not a trained engineer. I was going to designate the maintenance engineer with the control as the 'supervisor' for the activity. They could call me out to supervise the repair, but that would mean me being on call every day of the year, which is not really practical. We are a relatively small company with a total of 10 senior manager of which 4 have any real relationship to the production area. I would have thought that given suitable training in its operation, then the engineer on site would be fine in operating the controls. Finally I don't think I can really get away with not having people in there when the belt moves. Its essential in the fault finding process. I did think about putting cameras in so that you could see whats happening to the belt from the outside, but you'd need a lot of cameras to cover all the potential ponits were an error could occur. I'll let you know what I come up with in the end. Rob
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Posted By Merv Newman
Rob,
I think I understand your situation but our job really is 24/24, 7/7
15 years in the job and I think I got called out about six times. Most usually 3 am (why 3 am ?) Once it was an LTI, twice to fire alarms and the others to oversee critical procedures.
I would never ever trust a production manager to oversee a confined space entry. They are too much interested in getting production back on line. I would be more comfortable with getting the company accountant out of bed. (suitably trained) or, preferably, the MD.
One, it emphasizes the importance of protecting employee lives.
Two, the accountant or MD will have a pretty good idea of how much it will cost the company and the "controlling mind"
Three, having got the accountant or the MD out of bed a few times they will start to wonder if prevention is better than cure.
You may have gathered that I hate confined spaces. I will not let anyone in unless I am absolutely certain that they will come out alive. Combine CS with machinery that could be started by someone outside ? NONONONO !
Merv
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Posted By RBW100
Merv,
You do indeed have a strong feeling on confined spaces!
I would agree that my job (Chief Engineer / H & S Manager) is a job that you expect to be called out a various times. Not sure what your job is Merv, but called out 6 times in 15 years is not bad going!
I would generally expect to get called out to site around 1 or 2 times per month. My point it is not practical for any one to be on call 24/7 365. I am probably as close to this as is possible, I never have my phone turned off, and will come out to site unless I am on holiday (although I have attended site on Christmas day for an intruder alarm!) or would not be a deal of help (eg had 4 pints whilst watching the footy).
I fully understand your point with regard to production managers being more interested in production that anything else. I would hope that giving them the suitable training to oversee the entry would focus the mind on safety. After all they are the ones in overall control of the site at most times and hence have significant responsibilities in H&S.
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Posted By Merv Newman
Rob,
very good. We have the same attitude. I was plant H&S for about 15 years. Consultant H&S since 1989. And it really is 24/7
If they want you, they call you. You have to go. Even at 3am. But they should also call your boss. Or A boss. Anybody paid higher than you. A "controlling mind".
And one of these days we will find out why that conveyor keeps slipping off.
Merv
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Posted By Merv Newman
By the way Rob, welcome to the site. I hope you will put up a few more posers, and sometimes a few answers.
Merv
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Posted By Dean Pugh
Paul,
could I ask where you obtained your definition of a confined space?
According to the Confined Spaces Regulations 1997:
“confined space" means any place, including any chamber, tank, vat, silo, pit, trench, pipe, sewer, flue, well or other similar space in which, by virtue of its enclosed nature, there arises a reasonably foreseeable specified risk;
“specified risk" means a risk of—
(a)serious injury to any person at work arising from a fire or explosion;
(b)without prejudice to paragraph (a)—
(i)the loss of consciousness of any person at work arising from an increase in body temperature;
(ii)the loss of consciousness or asphyxiation of any person at work arising from gas, fume, vapour or the lack of oxygen;
(c)the drowning of any person at work arising from an increase in the level of a liquid; or
(d)the asphyxiation of any person at work arising from a free flowing solid or the inability to reach a respirable environment due to entrapment by a free flowing solid;
There is not any mention of one entrance etc. My point being follow the interpretations as laid down in the regulations and ACOP guidance.
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Posted By RBW100
Hi Dean,
From the ACOP list it would appear that the only thing that classes my freezers as being confined spaces would be the potential risk of ammonia leaks. I would have to say that this is an extremely unlikely occurance in my experience. More food for thought!
Rob
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Posted By Helen C
Hi there,
In reference to allowing operatives to detect ammonia by odour....please bear in mind that the 8 hr WEL for Ammonia is 25ppm and the 15 min WEL is 35ppm.
Ammonia can be detected using electro chemical sensors which will probably give the required level of accuracy but the majority of portable detectors I have come across are not rated to work in temperatures of less than 20 degrees C.
Infra red sensors may operate at lower temperatures but I'm not sure that Ammonia falls with the required wavelength range for detection via infra red.
Good luck.
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Posted By RBW100
I've been doing some more thinking on the ammonia issue. It sprung to mind that I'd not been thinking of thermodynamics!
As the ammonia in the evaporator is at around -40 deg. C. it is under vacuum. Hence any leak would result in air being drawn into the pipework rather than ammonia leaking out. Experience shows that it takes around 2 hours for the ammonia in the evap to gain a positive pressure and hence be a release risk. However this will only happen if the compressors where to be shutdown. There for in this case I would recommend keeping the fridge plant running to prevent potential ammonia release.
Rob
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