# Interest group forums > Energy and Resource Conservation Forum >  Greener refrigeration system issues explained.

## AndyD

The newer CO2 refrigeration systems being used in supermarkets have had problems whereby pipework or fittings failures have cause explosions.

Less technical details are available here.

http://www.youtube.com/watch?v=anVaq...layer_embedded

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## desA

The green bottles?

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## Martinco

> The newer CO2 refrigeration systems being used in supermarkets have had problems whereby pipework or fittings failures have cause explosions.


Surely the "explosion" is only caused by CO2 gas escaping from the pipework at a great rate of knots as CO2 is not combustible.
But are you saying that they are now using CO2 instead of of the normal Freon gasses ? e.g. F12 , F 134a etc.

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## garthu

Oh i get it, its cause the "bottles are green"  :Confused: 

Quite a funny little clip though, those guys should be politicians  :Cool:

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## AndyD

Yep, CO2 is not combustible, it's just the gas escaping when pipework ruptures. The pressures are immense, over 100Bar (1500 psi) and there's quite an explosion when a rupture occurs.

CO2 is being heavily pushed for widespread use by governments. Large subsidies are available overseas to help offset the heinous costs involved for companies who make a commitment to use it. There have been a few incidents of failures where entire shopping centers have been evacuated and people hospitalized. I don't know if there have been any deaths yet but watch this space.

Green politics.

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## garthu

What intrigues me is if i was to come up with a fridge that operated on chlorine gas, i would probably get locked up for terrorism or something as it could effectively harm people if leaking.

But this one which could leave people with shrapnel and quite possibly dead is OK? and then is it even really green??

As you say green politics

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## Justloadit

Just making life easier for terrorism, all you kneed to bring a shopping centre to it's knees is to place a small charge along a CO2 pipe, and bam you have a disaster.

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## Martinco

> What intrigues me is if i was to come up with a fridge that operated on chlorine gas,


Garth.........the heat absorption fridges actually work with chlorine gas ! The ones Ouma use to have.

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## AndyD

The absorption refrigeration system uses ammonia or R717 as it's also known, mixed with water. These systems were the ones Ouma had and they're still available today especially as camping fridges because they can work with an LPG heat source as well as electrical. It's highly toxic but it's very energy efficient as a refrigerant. As long as it stays in the refrigeration system it's completely safe. Commonly the cause of it getting out is corrosion because of the water in the system.
Refrigerants being hazardous isn't necessarily a reason not to use them, a lot of domestic fridges in Europe use propane as their refrigerant nowadays which is obviously highly flammable when in the presence of air.

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## garthu

Wow, learnt something new here today! Actually interesting....

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## Dave A

> CO2 is being heavily pushed for widespread use by governments. Large subsidies are available overseas to help offset the heinous costs involved for companies who make a commitment to use it. 
> ...
> 
> Green politics.


Got to get those carbon credits somehow  :Roll Eyes (Sarcastic):

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## desA

> Yep, CO2 is not combustible, it's just the gas escaping when pipework ruptures. The pressures are immense, over 100Bar (1500 psi) and there's quite an explosion when a rupture occurs.


There is also generally, compressor oil being transported around the refrigerant circuit. This oil can catch fire of an occasion with some systems. Not sure how much of an issue this may be with CO2, but at up to 150bar in some applications, the results could be interesting.

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## AndyD

> There is also generally, compressor oil being transported around the refrigerant circuit. This oil can catch fire of an occasion with some systems. Not sure how much of an issue this may be with CO2, but at up to 150bar in some applications, the results could be interesting.


I'm not a refrigeration engineer but I've spent the last three months doing lots of homework.
Oil catching fire might be a problem if a larger propane system had a big leak. Oil leaks from other refrigeration systems can be very acidic which is another problem. CO2 systems tend to run in a flooded state so liquid co2 could escape in the case of a large leak or pipework failure. CO2 much prefers to be a gas (or even a solid) a room temperature and pressure so the liquid would violently boil freezing anything it came into contact with. Cold burns to a person are just as bad and possibly life threatening as heat burns.

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