Co2 Explosion in Tesco store Manchester [Archive] - Refrigeration-Engineer.com forums

supermarketguy

12-12-2010, 10:10 PM

Hi all,

Just read this on line,

HUNDREDS of people were evacuated from a supermarket and shopping centre after an explosion which left eight people injured.
Shoppers ran out in panic from the Ellesmere Centre in Bolton Road, Walkden (http://www.refrigeration-engineer.com/search/?search=Walkden), after a fridge apparently exploded in the new Tesco Extra supermarket.
Witnesses described hearing a loud bang and seeing the shop, which was packed with Christmas shoppers, fill with white smoke.
It is thought that a pipe in a refrigeration unit ruptured and spewed carbon dioxide into the store, which only opened in September at a cost of £25M.
Eight people were treated by paramedics after the incident for shock and smoke inhalation.
No-one suffered any serious physical injuries, but a pregnant woman, a 76-year-old man and two asthmatics were among those treated.
Five of the casualties were taken to the Salford Royal Hospital and one to the Royal Bolton Hospital as a precaution.
Firefighters from Farnworth and Eccles attended the incident, which happened near the meat aisle at about 3.10pm yesterday.
Security staff evacuated the whole shopping centre because of the possible hazardous gases that had escaped from the ruptured unit.

This may make up this particular retailers mind on which way to go with this particular system.

Supermarketguy

Brian_UK

12-12-2010, 10:21 PM

It must be true, the BBC reported it as well. ;)
http://www.bbc.co.uk/news/uk-england-manchester-11979213

cool runings

12-12-2010, 11:39 PM

.

I'm not suprised it has happened and I'm glad nobody was hurt.

C02 is going to be a big part of supermarket refrigeration, but reports like this may just convince the big names that C02 is not worth the risk.

Same reason Ammonia is not popular in shops...

All the best

coolrunnings

.

lawrence1

12-12-2010, 11:53 PM

It was bound to happen,,,very luck no one was badly hurt.Can someone find out the cause of the leak?

fridge-spark

12-12-2010, 11:53 PM

I heard it was a lok ring that failed. I'm not sure this is true but I do know Tesco have them fitted on installation.

I hope no one was seriously injured. But it dose raise the question what would have happened if an engineer was working on / near the pipework at the time.

mad fridgie

13-12-2010, 01:11 AM

May I ask are these CO2 systems trans critical, or cascade based system (Main CO2 system at -10C, pump recirc for MT applications and a deadicated LT compressor)
If is the second option then your are working with system pressure similar to the high side of a R404a system. (20 -30 bar), so I see no need to scare anybody about CO2 usage, if transcritical (above 75bar) then these are pressures most are not used to dealing with.

I do remember on a number of occassions both in the UK and NZ when a liquid line flares had given away and filled a supermarket with R502 and/or R22 and went with a precieved bang.

CO2 is not explosive.

desA

13-12-2010, 04:29 AM

I have always been surprised that transcritical hot-water heat-pumps have not seen more press - especially in Japan where they seem prevalent.

Magoo

13-12-2010, 05:01 AM

Something was bound to happen that the rocket scientist did not predict, low ambients etc., sad really.
I will stick with ammonia, and drive my car with it like a NOS effect.

RONB

13-12-2010, 08:49 AM

I have installed/commisioned quite a few sub crit systems and they have all been braized pipe systems. I know it is a nightmare fully purging and getting 100% penetration etc. But I dont care what anyone says a correctly braized pipe joint against ANY mechanical joint wins hands down. Just imagine if the cabinet in question was a FGD and the evap gave way with flying glass etc,it just dose not bare thinking about. As Magoo states the rocket scientists have a lot more R+D to do on CO2 systems. Yes I understand the benefits in running cost/gas price etc, but at the moment the negatives outweigh the positives in my opinion.

lawrence1

13-12-2010, 11:07 AM

So does anyone know if it was a trans critical or sub critical/liquid pump m/t and what actually let go?

Blinky

13-12-2010, 07:41 PM

it was trans-crit, a vulcan lock ring blew, and the pipework was a tangled mess on top of the cabinets as the tile and bed wasnt clipped down sufficiently.
i dont trust these fittings at all, i have had them blow on 404a, however Vulkan always say it it always human error why they fail!!

bill1983

13-12-2010, 09:03 PM

"this may just convince the big names that C02 is not worth the risk"
come on! co2 was used for the first 60 years of commercially viable refrigeration on board ships
installed correctly, it's no more dangerous than hydrocarbons in your average integral. The pressures are only scary until you get used to them. The engineers of the early 20th century had to deal with it. surely we have advanced from then.
Admittedly lokring, if it was in this case, may have to revise their installation procedures. otherwise, strength test procedures and insurance certifiation may need investigation.

Keef_Controls

13-12-2010, 09:42 PM

A Vid...

http://menmedia.co.uk/manchestereveningnews/news/s/1388756_video_eight_hurt_after_blast_at_salford_tesco_store

I reckon most of joe public thought it was terroist attack ! :eek: not good....

supermarketguy

13-12-2010, 10:13 PM

Hi All,

Now hearing on the grapevine, that this particular retailer is ending its C02 installations. It appears that they may fufill their current commitments into next year and then these installs will cease :)

Where they will go next, will be anybodys guess, Ideas on a postcard please!!!

cool runings

13-12-2010, 10:35 PM

"this may just convince the big names that C02 is not worth the risk"
come on! co2 was used for the first 60 years of commercially viable refrigeration on board ships
installed correctly, it's no more dangerous than hydrocarbons in your average integral. .

C02 is one way forward and it is a good refrigerant as refrigerants go.

C02 has been used for decades, but it is quite new in the supermarket industry.

Now as for my "this may just convince the big names that C02 is not worth the risk" statement.

C02 and Ammonia are unknown to lay people, they do not know the benifits but they hear the scare stories and think they kill..

Now we have had an "Explosion" as reported in the press. A fitting burst, but people only read C02 = 8 injured.

You try selling C02 to Tescos now!!!!!

So before you jump on my coment just remember I'm sold on C02, its the public who shop in these places and if a few of them
are heard to be saying I won't shop in there, it has fridges that explode...

coolrunnings

.

coolhibby1875

13-12-2010, 10:54 PM

Hi All,

Now hearing on the grapevine, that this particular retailer is ending its C02 installations. It appears that they may fufill their current commitments into next year and then these installs will cease :)

Where they will go next, will be anybodys guess, Ideas on a postcard please!!!

if Tesco end its comitment to c02, you can bet the rest will too, and if this is the case it will be a disaster for the copanies that deal with supermarkets, as some have invested heavily into the co2 r&d, i can here engineers saying this stuff is safe if used properly and it is, however throw the general public into the mix and nothing is safe, store managers putting presure on engineers who havent the balls to say no and pressured into cutting corners and kaboom, another fridge blows.
i know every store that gets installed is different from any thats already been done, so lots and lots of tweeking controls here and there, this makes things interesting as controler manufactures and making it up as they go along!! this stuff is great for industrial equipment, yes!! for servovers and full glass door freezers in busy retail outlets!! I dont think so:eek::eek:

panda

13-12-2010, 11:50 PM

Well done Asda!!!!

They did 1 and decided stick with simple fridge. 1 scroll pack above 1 island, low entrained volume,no major issue if comp on pack fails and 1 engineer req to replace scroll if faulty. Hear hear Mr Churchyard!!!!!!!!! its about time you won all at the cooling awards in 2011:o!!!!!!!!!!

desA

14-12-2010, 04:33 AM

In my view, CO2 trans-critical systems suffer from excessively high pressures. This has always been a concern to me, I have to admit. If this piping had been in another location, a few shoppers could very well have been seriously injured.

This aspect has to be considered for future implementations. Imagine the fiasco a few years down the line, as systems begin to wear.

Now translate this to trans-critical hot-water heaters. If the units do not use sanitary grade gas coolers, people will most definitely be injured. Not good.

lawrence1

14-12-2010, 04:39 AM

Worse job around at the moment would have to be the old lok ring salesman.

750 Valve

14-12-2010, 09:49 AM

Scary Co2..... blah blah blah....

A spoon full of cement is urgently required for Tesco and whinging fridge engineers the world over.

coolhibby1875

14-12-2010, 02:16 PM

Scary Co2..... blah blah blah....

A spoon full of cement is urgently required for Tesco and whinging fridge engineers the world over.

due to some privacy settings on the company pc, i cannot post a link to footage taken from the store at the time of the explosion, but i can assure you that the women and children were not thinking blah, blah, blah when they were running from the store screaming in tears, i dont want to get into another debate on here with someone, however because you have C02 in stores down under which run perfectly well, that does not mean engineers all over the world are running scared of the stuff, if memory serves me correctly 2 engineers have been killed in Denmark using C02 and now this over here, no one wants to be hurt whilst out buying a pint of milk, and i can assure you as long as the diluted workforce of the refrigeration industry here in the uk are sent out to repair this stuff that is what will happen, there are fridge enginers out there not capible of looking at a simple pack on r404a taking a 2 day course on C02 then being let loose on the equipment, i know lots of guys who have done the training from many different companies and have the cert to say they are compidant to work on C02 plant and quite frankly they aren't capible of correctly changing out a pot on an integral cabinet, again i dont blame the engineers for this and i use the word ENGINEERS very loosely, i blame the companies for driving the cost of contracts down to a point that low that they canot pay the money to keep the real engineers within the industry in the supermarket sector, now thats whats SCARY!!!

mr.cold

14-12-2010, 02:55 PM

I'm sorry, I may be wrong but I didn't find any direct reference to CO2 in the linked articles in previous posts.
Are you sure we're talking about a transcritical CO2 system?
If yes: usually the part of the circuit inside the store is at low pressure, that means in the worst case (dx expansion and long stand-by of the system) 40/45 bar versus a PS= 30 bar of a standard refrigerant system: not such an extraordinary difference... as long as same safety corefficients for dimensioning are used.

Bye

fridge-spark

14-12-2010, 05:52 PM

I'm sorry, I may be wrong but I didn't find any direct reference to CO2 in the linked articles in previous posts.
Are you sure we're talking about a transcritical CO2 system?
If yes: usually the part of the circuit inside the store is at low pressure, that means in the worst case (dx expansion and long stand-by of the system) 40/45 bar versus a PS= 30 bar of a standard refrigerant system: not such an extraordinary difference... as long as same safety corefficients for dimensioning are used.

Bye

The intermediate pressure after the high pressure valve and up to the evaporator expansion valves (liquid line) has a PRV rating of circa 75 bar I guess that is why lokring fittings are used and pipework is not brazed.

fridge-spark

14-12-2010, 06:01 PM

Hello Coolhibby,

I totally agree.

due to some privacy settings on the company pc, i cannot post a link to footage taken from the store at the time of the explosion, but i can assure you that the women and children were not thinking blah, blah, blah when they were running from the store screaming in tears, i dont want to get into another debate on here with someone, however because you have C02 in stores down under which run perfectly well, that does not mean engineers all over the world are running scared of the stuff, if memory serves me correctly 2 engineers have been killed in Denmark using C02 and now this over here, no one wants to be hurt whilst out buying a pint of milk, and i can assure you as long as the diluted workforce of the refrigeration industry here in the uk are sent out to repair this stuff that is what will happen, there are fridge enginers out there not capible of looking at a simple pack on r404a taking a 2 day course on C02 then being let loose on the equipment, i know lots of guys who have done the training from many different companies and have the cert to say they are compidant to work on C02 plant and quite frankly they aren't capible of correctly changing out a pot on an integral cabinet, again i dont blame the engineers for this and i use the word ENGINEERS very loosely, i blame the companies for driving the cost of contracts down to a point that low that they canot pay the money to keep the real engineers within the industry in the supermarket sector, now thats whats SCARY!!!

vladsabin

14-12-2010, 06:31 PM

Scary yes, High Pressure yes and if this were not enough resons against CO2, lets not forget that an installation with CO2 is far more complex.
A more complex system needs more atention for maintenance.
Even more the price of the components and their maintenance is higher.
This would actualy rise the potential risk of an accident.

Let's not forget that CO2 was used before, but they did discover the ***** gases because CO2 was a problem.

supermarketguy

14-12-2010, 07:40 PM

Hi All,

I have to say C02 as a refrigerant, from what i have seen does what it says on the tin and is an extremely efficent refrigerant. I have no real issues working on these systems, it is more about the quality of the installation and the equipment that needs to be concentrated on and that all contractors involved are given adequate commissioning time on site to check everything over.

I have been involved in a few jobs and i am still getting commissioning times cut on them and then the reailler gets all uppity, when there is problems on and after opening day.

All the retailers have coe(centre for exellence) and have published commissioniong time scales, but when brought to site meetings, all they do is use them for scrap paper, as the store development managment dont have the balls to give us more time to commission if the builder holds us all up.

I am not saying that the problem that has occured in the store in question is down to commissioning time, but people are in a hurry to install everything as the retailer presses to reach their deadlines and things can be missed.

Rant over!!!! :)

Paul maye

14-12-2010, 08:17 PM

I work on co2 packs at tesco I won't say what company I work for but they have had me working on the stuff with no training,it took just over a year to have my one day course from star refrigeration.so does that make me qulified? Think not...still ****s me up every time,anyone who says you should tell your company or health and safety manager the situation do not work for a big fridge company cause it falls on deaf ears..some day someone will kop it cause we have not enough engineers and tesco just keep on demanding and demanding,it was only a matter of time..

mad fridgie

14-12-2010, 08:17 PM

I have had problems with lokrings, but I must say the problem was human error. They are great when you have easy access, "on a bench" but out on site where room for positioning is not always ideal,is where the problem lies.
You think that your tubes are inserted fully, but the time you jiggle you tool and stress the piping, the tubes are not always fully inserted. You end up with only a very small point of contact between the tube and the lokring crimp.

jonjon

14-12-2010, 08:55 PM

must of been the samw firm that put up the roof in tesco in s****horpe

http://www.thisiss****horpe.co.uk/news/Staff-s-quick-action-remarkable/article-2975348-detail/article.html

750 Valve

14-12-2010, 10:40 PM

Coolhibby it is not Co2 that is the problem here - a joint failed so look at why it failed, learn from it and move on. I have seen people run from a 404a leak just like that when a builder sawed through some underground lines - was there ever any thought of not using R404a???? I have seen header end caps blown off and discharge lines peeled open - all with r404a - once again was there ever any thought of not using R404a???

Don't get caught up in the whole scary Co2 thing - take the time - instead of whinging, to help those techs less mentally endowed than yourself by giving them pointers on what NOT to do, take the time to point out (and document) your concerns and the implications of sending untrained staff there to work on the equipment - no OHS rep wants to have a death at work on their head and they will do anything needed to ensure that they make the required recommendations to alleviate any exposure (ie cover their arses), this can only be a good thing as it means more training and exposure for techs.

Now I agree that all we have is a short course and we are let loose on Co2 systems, problem is you need to LISTEN and LEARN in the courses - you can lead a horse to water but you can't make it drink, aside from the safety concerns there is nothing you will learn at a co2 course that you should not have already comprehended from basic training during your apprenticeship (critical points, triple points, enthalpy diagrams, etc) so how many times do you need to be told that it is high pressure and can kill you? Guess what hydraulics are high pressure and can kill you too - look at how common they are! If you look at the amount of ammonia out there and the courses for that, given somewhat parity between the training required to service R744 and R717 (at least in Australia) why do we not have a groundswell of people saying how bad R717 is???? Engineers the world over can cope with it - all you need to do is show the proper respect, so too with Co2. It seems like the installer did not pay the proper respect to the systems high pressure requirements when installing the Lokring if it failed - this can and will come down to time and pressure from the likes of Tesco wanting a store open but this unfortunate accident needs to be highlighted as an example and the installing contractors need to stand up and say NO, safety first and that requires adequate installation, pressure and integrity testing and then commissioning time. Put the pressure back onto the builder and not the fridgie.

Bottom line from me is don't whinge - learn from it and do something about it so it doesn't happen again.

And for those who say "oh he mustn't work for a supermarket company - get real they don't listen" I have been in the supermarket game for 10 years and some of that working directly for a major chain - let me tell you they are anal about safety and **** scared someone will get hurt in their stores - contracting companies need to grow a set and use it to their own benefit, once a safety concern is documented it needs to be addressed.

750 Valve

14-12-2010, 11:25 PM

Another factor is putting the cart before the horse.

Yes we can do sub and transcritical systems and they work. Do we have the knowledge, skills, training, parts infrastructure, materials and tech support to make it a reality right now??? Maybe not.

Maybe we hold off on transcritical until the trade catches up with sub critical (less pressure, less exposure to new materials and joint methods) or if we go trans build in a safety factor, ie steel pipe all welded and x-rayed.

Because an engineer sits in an office and says "I want", does it mean he gets? As I mentioned before contractors need to get real and grow a spine - if it means staying out of the Co2 game until they are confident to enter then so be it. There are quite a few supermarket contractors over here that have done just that, their doors are still open and they still have employees working in supermarkets that get paid each week.

So too the individual techs, if it scares you to work on it then don't! Try to explain to your company and if they won't listen then leave. Its fine to say "but there are no jobs out there in this climate" - these are the same people saying they don't want to die at work - so don't and actively do something about it. Go work A/C for a while until the right job comes along.

Don't get me wrong - this is a serious incident and I'd hate to think what would happen if someone was actually working on the case at the time but if the knee-jerk reaction is to ban co2 in all Tesco then what do they do about the existing installations - do they need to be investigated from an integrity standpoint? Do you rip them out? Eventually someone else is going to come across the same thing and to me it makes more sense to get to the root cause of the problem before taking any action - sure its fair enough to put any transcritical stores on hold until a full investigation can be done but without going through the motions there is a possibility this can happen again on another site. And then if the problem can be resolved and provide minimal exposure to a reoccurrence then why stop rolling out Co2 as the exposure to another similar incident has just been rectified?

Too many people sit back and whinge these days and won't do a thing to help their own cause. If nobody ever speaks up then nothing will ever change, supermarket retailers should not be feared or loathed by engineers - its how we CHOOSE to make our money and the retailers are full of people just like you and me - blokes that put their pants on one leg at a time, who have families and lives outside of work - sure they are usually under a good bit of pressure at work (this is the nature of retailing on a large scale) and can be a little short at times but they are human just like you and me. The decisions they make can affect millions of people and this not only needs to be understood but can be used by smart contractors to their advantage or to help shape an outcome that is a win/win for all those involved.

***** END OF RANT *****

desA

15-12-2010, 04:10 AM

I'm seeing lots of pro's & con's in preceding posts. What is becoming obvious is the need for a solid manufacturing, building & maintenance code for these high-pressure machines - whether CO2, R404a - whatever.

Codes exist in the petrochemical industry - for very good reason. We work with pressures in excess of 160 bar, but, very, very carefully. No shortcuts, or dodgy lockrings.

mr.cold

15-12-2010, 07:52 AM

The intermediate pressure after the high pressure valve and up to the evaporator expansion valves (liquid line) has a PRV rating of circa 75 bar I guess that is why lokring fittings are used and pipework is not brazed.

Good point Fridge -spark, thak you for explanation.

Bye

coolhibby1875

15-12-2010, 12:05 PM

hi valve 750 again i stress the fact, i belive that C02 is good economical refrigerant, and should be rolled out more, however i find that having parts in fridges less than 12 inches away from where kids will be moving around containig gases in excess of 700 psi is just not good, parts will always break ect ect, and i think its wrong of you to compare r404a in a multideck chiller at 170 psi (liquid) and 45psi (suction) to 700 psi on co2, getting hit by a bit flying debris at 170 psi will hurt you possibly take out an eye, getting hit by a flying debris at point blank range at 700 psi will kill you.
i agree that your point of improving on the systems is the way forward, however tesco and the likes do not have the time to do so, whatch the footage of the people running from the building and tell me if you were a director of tescos would you want this to happen again, they do not need this type of publicity and more importantly they do not need to be banged up in the courts on lawsuits with people being hurt buying a pint of milk!!

Wingco

15-12-2010, 01:24 PM

Have heard it was due to a compression fitting on copper to copper conection failing. Cannot confirm this is true but given the nature of the failure this would explain what has been reported.

If joints are correctly made, compression or brazed there should be no such issues. Personally I would prefer to see brazed connections where ever possible. If these fail, they do not fail as a rue catastrofically, but compression fittings could.

There is no issue with Co2 as long as standards are adheared to and followed and correctlly engineered. There are many other industries out there that use far higher pressures without incidents.

Co2 can only be good for our industry as long as the training given is sufficient.

:D

750 Valve

15-12-2010, 10:04 PM

and i think its wrong of you to compare r404a in a multideck chiller at 170 psi (liquid) and 45psi (suction) to 700 psi on co2, getting hit by a bit flying debris at 170 psi will hurt you possibly take out an eye, getting hit by a flying debris at point blank range at 700 psi will kill you.

Mate its all relative to the burst pressure (actually to the design pressure) of the pipework carrying the refrigerant. As i said before perhaps an alternative pipe and jointing method is required to ENSURE things like this cannot happen.

As I have said before I have seen copper peeled open due to liquid hammer on a 404a system, the same lines that are less than 12 inches away from the kiddies getting their milk with the same potential for an incident. Now the leak that ensued sure scared the hell out the people that were present, evacuated the shopping centre and made the nightly news.... I don't see a big difference in the people's reactions in that video. The problem was the piping method used - not the R404a in the lines.

It seems you just do not understand - it is not the refrigerant, it is the manner in which the installation has taken place that has created the risk. By your logic (blaming the refrigerant) all we should have is chilled glycol pumping through cases at 2 bar as anything else has exactly the same potential, so too air conditioning on that nastily high R410a - you think we have untrained staff in supermarkets, look at all the cowboy A/C guys getting around.

fridge-spark

15-12-2010, 11:34 PM

The main issue here is cost. Should the entire installation be steel and tig welded? The only real issue with CO2 is containment.

Mate its all relative to the burst pressure (actually to the design pressure) of the pipework carrying the refrigerant. As i said before perhaps an alternative pipe and jointing method is required to ENSURE things like this cannot happen.

As I have said before I have seen copper peeled open due to liquid hammer on a 404a system, the same lines that are less than 12 inches away from the kiddies getting their milk with the same potential for an incident. Now the leak that ensued sure scared the hell out the people that were present, evacuated the shopping centre and made the nightly news.... I don't see a big difference in the people's reactions in that video. The problem was the piping method used - not the R404a in the lines.

It seems you just do not understand - it is not the refrigerant, it is the manner in which the installation has taken place that has created the risk. By your logic (blaming the refrigerant) all we should have is chilled glycol pumping through cases at 2 bar as anything else has exactly the same potential, so too air conditioning on that nastily high R410a - you think we have untrained staff in supermarkets, look at all the cowboy A/C guys getting around.

GreenCooling

16-12-2010, 12:53 AM

Thank you 750 Valve for being such a sensible voice of reason in response to some of the misplaced speculation on the future of CO2 from more excitable participants, remarkable that in spite of frequent similar failures of R22 and HFC systems some people are so quick to rush to judgement on CO2.

Certainly the change to higher pressure gases presents challenges for the industry, and there will always be laggards that resist rather than embrace change in any field. The critical point is that there are lessons to be learnt from this incident, and all the comments about the need for better training deserve to be heeded.

Life long learning and keeping up with new developments is a requirement in any profession - engineers exist to solve problems and deliver safe systems to meet the needs of their customers and society. It's just silly to be suggesting that CO2 is all too hard and suggest the industry should hang on to the environmentally damaging refrigerants that all responsible users are rapidly trying to move beyond.

In case anybody missed it the global commercial refrigeration industry, under the umbrella of the "Consumer Goods Forum" announced on day 1 of the Cancun climate conference that they want to go HFC-free by 2015 (admittedly they've left some wiggle room in this goal) and move to natural refrigerants. So anyone wanting to do business with these 400+ global companies would be well advised to adopt an innovative mindset and invest in the training needed to handle high-pressure and flammable refrigerants.

Those interested in keeping informed on this incident may like to check out the story at r744.com/articles/2010-12-15-tesco-co2-incident-looking-at-the-facts.php and their follow up articles...

phil Landon

16-12-2010, 01:01 AM

Hey there, Have been working on CO2 systems for a couple of years and all our pipework is brazed, dont have a problem with the system itself as it works really well. It sounds like the lok-ring coupling was the culprit as reported on R744.com. That comes down to using a new type of coupling, maybe they should go back to the old tried and true methods of pipework

Mark

16-12-2010, 03:20 PM

www.r744.com/articles/2010-12-16-british-refrigeration-association-to-develop-co2-training-standards.php

www.r744.com/articles/2010-12-15-tesco-co2-incident-looking-at-the-facts.php

www.racplus.com/news/industry-in-discussions-to-produce-co2-training-standard/8609176.article

TriplepointPerk

16-12-2010, 06:24 PM

hi all,

i have to say c02 as a refrigerant, from what i have seen does what it says on the tin and is an extremely efficent refrigerant. I have no real issues working on these systems, it is more about the quality of the installation and the equipment that needs to be concentrated on and that all contractors involved are given adequate commissioning time on site to check everything over.

I have been involved in a few jobs and i am still getting commissioning times cut on them and then the reailler gets all uppity, when there is problems on and after opening day.

All the retailers have coe(centre for exellence) and have published commissioniong time scales, but when brought to site meetings, all they do is use them for scrap paper, as the store development managment dont have the balls to give us more time to commission if the builder holds us all up.

I am not saying that the problem that has occured in the store in question is down to commissioning time, but people are in a hurry to install everything as the retailer presses to reach their deadlines and things can be missed.

Rant over!!!! :)

hear hear!!

trampus

16-12-2010, 06:54 PM

This was bound to happen sooner or later,the higher the pressure of refrigerants the more likely a rupture will happen. I may be wrong but Co2 will not take over as a serious refrigerant.

CAPTAINBIRDSEYE

16-12-2010, 08:46 PM

Cant wait to see the HSE report mind you i tend to agree the high pressures i.e upto 75KPa 0r approx 1100 psi PRV on the low side is more than a tad silly its verging on crazy. heard all the stats etc but assuming were talking about the external compound trans critical packs

panda

18-12-2010, 01:17 AM

Guys

Anyone know how much this has cost tesco? Would not have happened under Dave Downs. Are Space picking up the bill for the loss of trade me expects around 1 million?????? PS don't crimp when you can braze:D....

Regards

P:D

Spencer.Guy

18-12-2010, 06:09 AM

Guys

Anyone know how much this has cost tesco? the bill for the loss of trade me expects around 1 million???

I know Tesco is quite profitable, but the store only lost 40 minutes trade, 15.20 to 16.00, then re opened at midnight.

They couldn't possibly turn over 1 million in 40mins let alone make a profit of 1 million.

Judging by the size of the store, over 100,000 sqft, I would expect they only turn over around 2 to 2.5 million a week max.

I would also expect that the publicity from this has come out fairly neutral overall, yes they had an incident, but now everyone knows about co2 and that Tesco are using it and that they have a new store in Walkden..
.

acb

18-12-2010, 11:20 AM

750, im currently training on co2 in scotland, and got to side with coolhibby on this one.

its not about the co2 itself, its all about the chain of events after a company is awarded the install contract.

firstly, contracts are awarded to the lowest bidder and not the company with the best trained engineers, and from experience these companies (2 in particular) cant even put in a 404a sytem that doesnt leak, why?? because in order to win the contract with lowest bid they cant afford the best engineers nor can they afford to spend any more time on site than absolutly neccessary or they loose money.

secondly, its clear that cases being put in are the cheapest going, cos the case manufacturers cant even get something as simple as getting the water to flow towards the drain correctly, this just shows even more cost 'savings' are being implemented.

add all this together and boom, someone gets hurt, i dont want that to be my wife or kids.

GGMarquez

20-12-2010, 11:17 AM

The difference between CO2 designs in Denmark and the one from Tesco, is that the working pressure in cases (doesn't matter if it is a transcritical or subcritical installation) never exceeds that of 30-35 bar. That is not much higher than MWP of R404A. All standard components can cope with that. I think the discussion should be about system configuration and not CO2 as a refrigerant.

multisync

20-12-2010, 03:03 PM

must of been the samw firm that put up the roof in tesco in s****horpe

http://www.thisiss****horpe.co.uk/news/Staff-s-quick-action-remarkable/article-2975348-detail/article.html

Newsflash::

Tesco to ban roofs!

taz24

20-12-2010, 03:18 PM

The difference between CO2 designs in Denmark and the one from Tesco, is that the working pressure in cases (doesn't matter if it is a transcritical or subcritical installation) never exceeds that of 30-35 bar. That is not much higher than MWP of R404A. All standard components can cope with that. I think the discussion should be about system configuration and not CO2 as a refrigerant.

I think that the systems are the same.

Running pressures do not rise that high.
But standing pressures do???

The tesco job failed from what appears to be a faulty or poorly fitted joint??
That joint coud have failed with any refrigerant behind it :eek:

I bet when it is looked into it will come back to the guy who installed the joint :rolleyes: :rolleyes:
Someone will be blamed and then we will carry on as normal untill the next incident (if there is one).

taz

Ps valves and joints failing is not new.

I was once called to a supermarket with R22 subcooled liquid compound packs and the hot gas defrost
mag valve had blown completely off.

High pressure, misty refrigerant vapour vented into the store from the top of a case.

The fire crews were wearing BA equipment and were not too keen on me going in I walked
in unsupervised by a side door, 3 valves, 30 secs later = all sorted.

Chief fire officer threatend to report me publicly :confused: but thanked me when we were away from the crowds :D

Red tape stops the fire services using civilians, even if they are more experienced than themselves.

taz

.

tajger

20-12-2010, 09:19 PM

The difference between CO2 designs in Denmark and the one from Tesco, is that the working pressure in cases (doesn't matter if it is a transcritical or subcritical installation) never exceeds that of 30-35 bar. That is not much higher than MWP of R404A. All standard components can cope with that. I think the discussion should be about system configuration and not CO2 as a refrigerant.
I'm quite sure you are using Green&Cool trans-crit machines in Denmark, and the liquid line working pressure is higher than 35 bar. I'm looking at one right now. Pressure is as follows:

After gascooler: 62 bar
Liquid line: 48 bar
Suction for cooling: 24 bar
Suction for freeze: 11 bar

Outdoor temperature is -9C.

supermarketguy

20-12-2010, 11:21 PM

Hi All,

It has been intresting to see everybodys opinions on this particular subject matter and you have to respect everybodys point of view.

Initially when C02 systems were first muted and the scare stories started about the working pressures, there was a bit of uneasyness about working on these systems. :eek:

But as with everything, a bit of fear can be a good thing as you treat these things with a bit of respect and tread carefully into these things.

With standard retail refrigeration systems, you can be complacent with them and you all know what you can and can not do. Co2 is a new learning curve for all of us and i understand the need for training and especialy the H&S aspects., but the training is two way street for the customer and the company to absolve them of liability and for you to understand what you are dealing with.

I have to agree with 750 Valves posts in this thread, that you can go on all the courses, but you will not learn as much untill you are standing in front of it, trying to suss out what is going on. I have been in the past few months been involved with both the commissioning and service side of things with these systems with diffrent retailers.

I have learned more in the last few months, working on these systems than i would ever going on a course and treat every job i go to with respect, as you never know what you may encounter and i have to say despite the problems i have encountered and there have been many!!!!. I am enjoying it as i am learning something new.

What has been good is that a dialogue with all the engineers within my own company and people you know within other companys and we are all learning how to over come the issues that arise, i feel that anything that makes us all sit up and talk about it is healthy and it has been a while that on particular system within retail has done this

This particular event has brought it to the fore and will focus the retailers on the way forward, as with all systems these will evolve and as issues arise the systems will hopefully get better and allay everybodys fears. c02 has been around for a long time and is not new, just new to the commercial sector and will probably be here to stay in one form or another.

It is a bit like marmite, you either love it or hate it, personally i am in the getting to know it stage of the relationship and things are going well, but time will tell. :)

padraic

03-01-2011, 02:56 PM

only 4 months working on co2 tran-subcrital and direct and have to say loving the change its really interesting... you have to be fearfull all the time and really think about what you are at and not get complacesent with is good..

compared to 134a the compressor can be 12-13 times smaller
compared to 404a the compressor can be 7-8 times smaller

due to its high volumetric capacity it is very efficient and your suction pipe is much smaller and not really any pressure drops

in the long run the customer will save on running costs so id say we will see alot more of it just needs a bit of fine tunings

i am new to this forum so just feeling my way thanks

coolhibby1875

03-01-2011, 09:31 PM

hi and welcom padriac, i am grey enough without having to be fearfull of just doing my work!!

padraic

04-01-2011, 09:16 AM

hi and welcom padriac, i am grey enough without having to be fearfull of just doing my work!!

stop got enough grey hairs in the last year between rescession and co2

chillled

06-01-2011, 03:09 PM

Apparenly its happened again, new year's eve at tesco accrington.
I have it on good authority that the manchester leak was a split lokring tee, mid fitting, not the part where the pipe joined.

smoggy

13-01-2011, 09:04 PM

is it right that some poor bloke burst his ear drums tyring to defrost a coldroom on co 2 or is it just hype

Bigfreeze

13-01-2011, 09:49 PM

is it right that some poor bloke burst his ear drums tyring to defrost a coldroom on co 2 or is it just hype

Haven't heard that but I do know that these systems give an incredible bang when a pressure relief valve goes. Even guys used to working on them nearly jump out of their skins. Like a couple of shotguns going off in a enclosed space

tony--1

14-01-2011, 11:06 PM

heard that theres been a lot of leaks of out of these fittings . not full blown but small leaks they sound sh*t to me . wats the crack with the vibros that you bend ? is that right ?

tony--1

14-01-2011, 11:08 PM

Apparenly its happened again, new year's eve at tesco accrington.
I have it on good authority that the manchester leak was a split lokring tee, mid fitting, not the part where the pipe joined.

i heard it was down to liquid hammer

tony--1

14-01-2011, 11:20 PM

http://www.racplus.com/news/

lmao

750 Valve

15-01-2011, 07:28 AM

Haven't heard that but I do know that these systems give an incredible bang when a pressure relief valve goes. Even guys used to working on them nearly jump out of their skins. Like a couple of shotguns going off in a enclosed space

Yes and its also turns you into a pumpkin at midnight!

In reality, the pressure relief valves that we use in Australia (cannot speak for the UK) do not open all of a sudden, they begin with a slow hiss then open and close rapidly (and sound like a machine gun but nowhere near as loud) as the pressure increases to be fully open at their design pressure, they reseat in a similar manner.

desA

15-01-2011, 07:36 AM

http://www.racplus.com/news/

lmao

That is lovely. :D :D :D

headgasket

15-01-2011, 09:30 AM

How many People sit in a office with a A/C unit just above there heads with 410a at 30 bar ? have you seen how thin the pipe work is on the coils. New technology is always scary until it old technology!!

desA

15-01-2011, 11:24 AM

How many People sit in a office with a A/C unit just above there heads with 410a at 30 bar ? have you seen how thin the pipe work is on the coils. New technology is always scary until it old technology!!

30 bar in the evaporator? :eek:

Brian_UK

15-01-2011, 10:13 PM

http://www.racplus.com/news/

lmao
Excellent system analysis. :D

r.bartlett

15-01-2011, 10:43 PM

30 bar in the evaporator? :eek:

Heat pump......

coolhibby1875

16-01-2011, 01:28 PM

http://www.racplus.com/news/

lmao

:):):) food for thought though

750 Valve

17-01-2011, 09:49 AM

:):):) food for thought though

unfortunately not exactly factually correct though, still funny none the less

Gary

17-01-2011, 02:52 PM

We hear a lot about the disadvantages, but not much about advantages. Are there any advantages?

Spencer.Guy

17-01-2011, 04:03 PM

We hear a lot about the disadvantages, but not much about advantages.

http://www.racplus.com/news/supermarket-co2-explosions-an-alternative-explanation/8609962.article

It comes in a Green bottle..

.

desA

17-01-2011, 05:34 PM

http://www.racplus.com/news/supermarket-co2-explosions-an-alternative-explanation/8609962.article

It comes in a Green bottle..

.

The green bottle part had me rolling on the floor... :D

Gary

17-01-2011, 05:50 PM

Doesn't R22 come in a green bottle?

desA

17-01-2011, 06:12 PM

LOL... Ten green bottles hanging on the wall... :D

r.bartlett

17-01-2011, 07:25 PM

Doesn't R22 come in a green bottle?

Not over here.. it comes in a grey bottle with a yellow neck

Greengrocer

18-01-2011, 02:35 PM

This arrived in my e-mail today via the HVCA (UK).

http://www.youtube.com/watch?v=anVaqtRx8S8&feature=player_embedded (http://www.youtube.com/watch?v=anVaqtRx8S8&feature=player_embedded)

Discuss.:confused:

OOpps. Looks like someone else got there before me. Thought I scanned the thread well enough before I posted. Obviously not.

750 Valve

18-01-2011, 11:00 PM

We hear a lot about the disadvantages, but not much about advantages. Are there any advantages?

Are you for real?

coolhibby1875

19-01-2011, 09:32 PM

Are you for real?

i dont want to get into a slanging match but what are the advantages?

Cantona

21-01-2011, 04:48 PM

if it was installer error why oh why are all 11/8" to 1/2" reducers being cut out of installations and Tesco are also thinking about removing these fittings from live stores.......also thinking of using stainless steel....go sub

mouse

21-01-2011, 09:55 PM

Refrigeration become a dangerous job in the future?;)

desA

22-01-2011, 05:10 AM

I think that painting the pipework green may help.

Bigfreeze

22-01-2011, 04:18 PM

i dont want to get into a slanging match but what are the advantages?

I'd like to know too, as I read a couple of manufacturers takes on this and the advantages they list I wouldn't see as a huge advantage at all. Certainly not worth the hassle involved with installation

Spencer.Guy

27-01-2011, 12:46 PM

I'd like to know too, as I read a couple of manufacturers takes on this and the advantages they list I wouldn't see as a huge advantage at all. Certainly not worth the hassle involved with installation

Keeps the Tree Huggers and Local Planners off the supermarkets' back.

I doubt it's being done for any cost saving.

.

mr pump down

29-01-2011, 10:41 AM

ive commisioned tesco and siansburys stores for around 16 years and have now stated commisioning and working on tesco co2 sites........i dont find any reason why people think that they are dangerous...???? it all comes down to the installation of the system....tesco do not clamp the headers and pipework to the tops of the cases, this combined with the fact they are using lockring is dangerous as far as i am concered..if the pipework was secured correctly then they would not get this vibration and movement in the piework that is causeing the lockring fittings to fail, this may take the instalation enginers longer to install and the cost and length of the instalation would increase but it would be a much safer system........the fact that they are now useing barsket case to cover the pipes in a joke as this would not contain the pipework if a lockring fitting was to fail as it is designed for holding data cables...consultants need to speak to co2 instalation and commisioning engineers then they would find a more pratical and profesional way of thinking when it comes to co2 supermarket instations....co2 has been around for a long time its no more dangerous than any other refrigerant out there....

r.bartlett

29-01-2011, 11:13 AM

ive commisioned tesco and siansburys stores for around 16 years and have now stated commisioning and working on tesco co2 sites........i dont find any reason why people think that they are dangerous...????

fact they are using lockring is dangerous as far as i am concered..

You may need to work on your joined up thinking but welcome to the forum :D

monkey spanners

29-01-2011, 11:17 AM

I think that painting the pipework green may help.

Good idea :D

750 Valve

29-01-2011, 12:16 PM

i dont want to get into a slanging match but what are the advantages?

Despite your not wanting to accept the movement of the trade into a new concept (which I do understand I am not having a shot at you as an individual, it is a common theme out there), and regardless of anyone's thoughts of "tree huggers" the fact remains that the commonly used refrigerants such as R404a have a global warming potential over 3000 times greater than that of Co2, even R134a is over 1000 times greater.

Given the avg supermarket chain's leakage rates and the cost of Co2 versus the increasing tariffs imposed by governments who have made a decision to listen to the "tree huggers" whether you, me or any other fridgie thinks its valid or not, it makes sense to lose 1 tonne (1,000kg) of Co2 per year as a leakage rate as opposed to leaking a tonne of R404a which has the equivalent environmental impact of 3600 tonnes (3,600,000kg) of Co2 and a cost 20 to 30 times greater. Go figure why the big players are changing!

In a transcritical application, given a warm climate there is absolutley no savings on energy - the only benefits come from reduced emissions related to refrigerant charge. However in cooler climates where the system can operate sub critical without the use of mechanical cooling then there is significant gains and according to actual data the power savings range in the vicinity of 0 to 10%, the cooler the climate the better the result. So given the UK climate (Co2 critical point is 32C - so below that can be subcritical) a company like Tesco is smart in trying to apply the technology as given the number of stores there is a significant cost saving on energy for them - 10% is nothing to sneeze at.

In a warmer climate such as we have here in Oz, transcritical is a waste, however properly designed subcritical systems can offer little to no penalty, the two majors in Oz are currently limiting their designs to LT DX systems running off the existing HT and MT racks, this saves a little on capital outlay (no LT condenser, just 2 HXs at approx 1/4 cost of air cooled condenser) and has no additional piping costs plus allows the stores to spend less on a condenser deck.

A small advantage is also in piping design, given the P/T relationship there is more leeway for suction line pressure drops to have less effect on system performance, allowing smaller suction lines to be run with little to no penalty.

I understand that people fear change, however given the rising costs in refrigerant based on GWP this alone means that the more system a customer owns the more attractive natural refrigerants are, nobody forces fridgies to fix supermarkets - most detest doing the work due to the managers and the hours. The small group that do like it, can learn and evolve with system designs will always be assured of a job and can take pride in the fact that they have the brains and the balls needed to be at the pointy end of the payscales.

Safety should always be first and foremost, learn from mistakes such as the Tesco explosions instead of running from the issues. Someone, somewhere will try the same thing and if the industry isn't given a chance to learn from the mistakes then the mistakes will be made again and again. There will always be those coming up with new technologies, new ways of applying current and future theories, its human nature - there will always be those happy to stay exactly where they are with the safety and knowledge of what works, this is also human nature. As an industry we need to find a balance.

desA

29-01-2011, 12:29 PM

Where does the CO2 in the green bottles come from?

r.bartlett

29-01-2011, 02:17 PM

Where does the CO2 in the green bottles come from?

Does Tesco's sell it...:confused:?

desA

29-01-2011, 02:50 PM

does tesco's sell it...:confused:?

lol... :) :)

Gary

29-01-2011, 03:53 PM

Winning the lottery is change. A sharp stick in the eye is change. "fear of change" is just a political buzz phrase, a thinly veiled insult. It is meaningless drivel.

charlie patt

29-01-2011, 06:39 PM

750 what attracts tesco to co2 the gwp or the cost of it for rechargeing a system the people that make these choices are cost involvement first if it helps any thing else then thats a benifit for them but not there priority. as in all installs there are always some snag work some small some large ,but personal safety is key to all work and progress, co2 may be the way forward but this is not good for it or any end user, customers running from a store is never good practice,but have they learned? is the install team had better training and being paid a decent rate to do the work ? if it costs more a doubt it and that not a go at tesco it just the way they work and this is where the problem lies it has to start at the top

750 Valve

29-01-2011, 09:11 PM

750 what attracts tesco to co2 the gwp or the cost of it for rechargeing a system the people that make these choices are cost involvement first if it helps any thing else then thats a benifit for them but not there priority. as in all installs there are always some snag work some small some large ,but personal safety is key to all work and progress, co2 may be the way forward but this is not good for it or any end user, customers running from a store is never good practice,but have they learned? is the install team had better training and being paid a decent rate to do the work ? if it costs more a doubt it and that not a go at tesco it just the way they work and this is where the problem lies it has to start at the top

No it starts at the contractor telling them why the mistake happened and what to do to fix it, if it means more install time or more guys on site then that is what it takes, yes supermarkets are ruthless but they are not stupid.

You are correct that the change is driven from a financial reason - that is a fact of life - get over it. If someone told you they could save you 10% off your power bill and cut down the cost of your leakage rate across 1000 stores at a leakage rate of 10% per year you would listen too! Bean counters run the world.

No Gary, drivel is your propaganda on servicing fridges, actually what you just posted is meaningless drivel - you tried to define what you think change is but failed to address the issue you had with my statement that some people fear change, and to you it may just be an insult, to others its just a fact of life that they are comfortable with their situation and do not see any reason to change the scenario (usually unless they can benefit directly from it). You stick to your R22 freezers if thats what suits you and let the rest of the industry sail by in front of your eyes.

Brian_UK

29-01-2011, 09:57 PM

You may need to work on your joined up thinking but welcome to the forum :D
Taking the comments out of context does not help your argument.

coolhibby1875

29-01-2011, 10:12 PM

is c02 plant more expensive to install than normall plant? yes.

does it cost more to run than normall plant ? yes

is the supermarkets paying contractors more to maintain thier co2 stores ? no

is co2 harmfull to the enviroment ? yes

do contractors have the funds to fully train the engineers ? no

is this a recipe for incidents to occur ? yes,

is it a matter of time before someone is hurt with co2 ? yes

benifits ? well im not completley sold on it, however i can see why some people are, i can tell you that the big chains here use it as a bargining chip with local goverments to get green belt space to build new supermarkets, they also use it to get goverment credits, if a chain like tesco build 10 stores a month and only put 1 in on co2, then it tells you that they are not to interested, and if they thought they could save 10% on thier energy usage they would refit every store as a matter of urgency, i have seen a trend in the big players swing towards hydro carbon and glycol in recent months, i think this will be more the way forward over the next 3 to 4 years, well i hope so anyway!

Gary

29-01-2011, 10:23 PM

If a new product is clearly beneficial, it almost sells itself. If the benefits are somewhat less clear, then some evidence may be in order... unless of course you are the government. Then you can simply pass laws and beat people into submission.

Goober

29-01-2011, 11:03 PM

Winning the lottery is change. A sharp stick in the eye is change. "fear of change" is just a political buzz phrase, a thinly veiled insult. It is meaningless drivel.What is this refering too? Missing something here.

750 Valve

30-01-2011, 03:07 AM

coolhibby it is obvious to me you just don't understand the key factors behind moving towards Co2, either you can't comprehend simple theories or you just don't want to (for example you say Co2 is harmful to the atmosphere - well check out the big brain on brad!!!! Of course it is, but when compared to the current alternatives it cannot be compared - Co2 has a GWP of 1, R404a has a GWP in the vicinity of 3600 - that is 3600 times as bad for the environment than Co2). I cannot see how you cannot understand this! It's like talking to a first year apprentice!

Anyway buddy you can be scared of Co2 and embrace HC's and when someone blows themselves up you can come back and whinge about exactly the same points - training, supermarket companies, energy, blah, blah, blah.

I might actually remind yo that you nobody forces you to work on Tesco equipment, if you don't like it then take a stand and go do some other form of refrig or air - if you are good you'll get hired straight away

If a new product is clearly beneficial, it almost sells itself. If the benefits are somewhat less clear, then some evidence may be in order... unless of course you are the government. Then you can simply pass laws and beat people into submission.

Ahh - another yank banging on about govt conspiracy theories, how original.

Gary

30-01-2011, 03:42 AM

coolhibby it is obvious to me you just don't understand the key factors behind moving towards Co2, either you can't comprehend simple theories or you just don't want to (for example you say Co2 is harmful to the atmosphere - well check out the big brain on brad!!!! Of course it is, but when compared to the current alternatives it cannot be compared - Co2 has a GWP of 1, R404a has a GWP in the vicinity of 3600 - that is 3600 times as bad for the environment than Co2). I cannot see how you cannot understand this! It's like talking to a first year apprentice!

As suspected, it's because the bottle is green.

BTW, nice response. Little substance and lots of insults. But then, why would we expect otherwise?

desA

30-01-2011, 08:23 AM

Where does the CO2 in the green bottles come from?

The video made a claim in terms of the CO2 being created from reaction of fresh carbonate-based material, in a chemical reaction. If true, this is an incredibly damning statement in terms of global 'active' CO2 balance.

Taking already stable forms of carbonate-based materials (where CO2 is essentially 'locked in', for want of simplification) & 'unlocking' the CO2 is very, very different to extracting existing CO2 from the atmosphere, storing it & using it. If this is then released, the 'active' CO2 balance is maintained.

Releasing 'locked in' CO2 into the environment is an incredibly foolish thing to do.

Is CO2 technology guilty of this? :eek:

coolhibby1875

30-01-2011, 12:39 PM

coolhibby it is obvious to me you just don't understand the key factors behind moving towards Co2, either you can't comprehend simple theories or you just don't want to (for example you say Co2 is harmful to the atmosphere - well check out the big brain on brad!!!! Of course it is, but when compared to the current alternatives it cannot be compared - Co2 has a GWP of 1, R404a has a GWP in the vicinity of 3600 - that is 3600 times as bad for the environment than Co2). I cannot see how you cannot understand this! It's like talking to a first year apprentice!

Anyway buddy you can be scared of Co2 and embrace HC's and when someone blows themselves up you can come back and whinge about exactly the same points - training, supermarket companies, energy, blah, blah, blah.

I might actually remind yo that you nobody forces you to work on Tesco equipment, if you don't like it then take a stand and go do some other form of refrig or air - if you are good you'll get hired straight away

if your quite finished with the insults, i will again go on and say, i dont see co2 as the answer, here in the uk a lot of the big supermarkets are turing to hydrocarbons and glycol, i love your enthusiasm and passion for embracing co2 i really do, but maybe thats born out the fact that Austrailians have the higgest carbon foot print per person in the world, i think with your passion for being green, you should challenge your goverment on the amount of coal it uses in power stations!! or mabe they cant comprehend the simple theories behind generating power other than burning coal, which in turn poloutes our atmosphere, like i say we all use this forum to express an opinion and have a laugh along the way, but there is no need for the insults, i stated at the begining only because it was you posting that i didnt want to get into a slanging match but here you are again throwing out insults!:(

Silhouette

30-01-2011, 04:48 PM

I've been commissioning Co2 systems for the last 12 months in JS, Tesco and morrisons. I've done the training courses (Morrisons, M&S, etc) and you don't learn much in the way of practical fault finding, just the H&S side of things along with basic theory on Co2 refrigeration.
I believe the recent explosions are down to a reducer introduced a few months ago to bring down the number of fittings used on installations and there is a current programme of replacement works.
For those not familiar with the Tesco system, it is a cascaded system with the LT subcritical packs using 3 plate heat exchangers cooled by 3 different HT packs as condensers. The HT packs are transcritical systems on a Low Pressure Receiver (LPR) design.
Personally I don't think the system copes well with the fluctuating loads we get in supermarkets!
The control system is a Danfoss 255 rack controller controlling, usually, 2 HT's and 2 LT's via input output modules in the plant itself.
It's all very complicated compared to a pack with its own dedicated controller:(

piewie

18-08-2011, 10:26 AM

This was a Star LPR system being developed and trialed by TESCO and others. Apparently the system has now been canned.

chillerman2006

18-08-2011, 12:25 PM

Hi all,

Just read this on line,

HUNDREDS of people were evacuated from a supermarket and shopping centre after an explosion which left eight people injured.
Shoppers ran out in panic from the Ellesmere Centre in Bolton Road, Walkden (http://www.refrigeration-engineer.com/search/?search=Walkden), after a fridge apparently exploded in the new Tesco Extra supermarket.
Witnesses described hearing a loud bang and seeing the shop, which was packed with Christmas shoppers, fill with white smoke.
It is thought that a pipe in a refrigeration unit ruptured and spewed carbon dioxide into the store, which only opened in September at a cost of £25M.
Eight people were treated by paramedics after the incident for shock and smoke inhalation.
No-one suffered any serious physical injuries, but a pregnant woman, a 76-year-old man and two asthmatics were among those treated.
Five of the casualties were taken to the Salford Royal Hospital and one to the Royal Bolton Hospital as a precaution.
Firefighters from Farnworth and Eccles attended the incident, which happened near the meat aisle at about 3.10pm yesterday.
Security staff evacuated the whole shopping centre because of the possible hazardous gases that had escaped from the ruptured unit.

This may make up this particular retailers mind on which way to go with this particular system.

Supermarketguy

Hi supermarketguy

It helped a lot of supermarkets make up there mind

& what have they started going for now ?

Hydrocarbon's

;):D;):D

chilliwilly

19-08-2011, 10:01 AM

I have heard that all coca cola equipment has gone co2. I haven't worked on any co2 equipment myself, but I have heard that you need to charge 30% gas stage only and run under charged for a few hours. Then top off remainder. That unfortunate instance is a kick in the b0ll0cks for the so called future of refrigeration.