CO2 Refrigeration

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UK:  Earlier this week we ran with this post following receipt of a link to two videos entitled 'Transcritical Co2 refrigeration pack EXPLODED!!' showing footage of the aftermath of a transcritical C02 refrigeration pack failure as a result of the rupture of the main Medium Temperature Suction line.

Incidentally, the failure occurred on 01-July, the hottest day of the year. Which according to the historical weather data for the area, the ambient air temperature reached 30C.

According to the narrative that accompanied the YouTube videos, this pack was less than 5 years old and all PRV's were in date. The ambient temperature was in excess of 45C and the resilience unit was running full tilt trying to lower the receiver pressure. The ETS valve was also open wide, dumping excess gas/pressure into the MT suction. The discharge pressure was up to 117 bar, condensers were clean and all fans running at maximum capacity.

The exact cause of this catastrophic failure had not been determined at the time of posting the footage but it was thought that it had to be a combination of factors, as all safety features (compressor unloading, Pressure Switches, PRV's etc) - that would have lowered the pressures, failed at a particular point in time.

In defense of engineer who uploaded the videos he did so because he felt that there was a real educational value in them from a Health and Safety perspective and as a reminder of the awesome power of C02. But rather disappointingly the engineer concerned subsequently came under a lot of pressure to remove the footage from YouTube and hence did so.

We've put together a few of the frames from the footage which show the devastation caused

This post is most certainly not to sensationalise the incident or to criticise Co2 as an application, but solely to raise awareness to the refrigeration community as to the hazards involved when working with Co2. If anything it has raised questions among the 1,200 engineers who follow our Facebook page about the regulations surrounding the frequency of inspection and testing of PRVs, of which many unsurprisingly weren’t aware of. So if nothing else, this post as intended, has created healthy and relevant discussion.

There are undoubtedly a number of factors that led to this incident some of which we have been made privy too but unfortunately are unable to share publicly. Lets just hope that everything is being done to mitigate such an occurrence happening again and valuable lessons are learnt and hopefully shared.

Finally whilst we believe unrelated to this incident, we've come across a number of codes of practice for Co2 that state that outlet piping should not be added to CO2 relief valves because there is a danger of dry ice formation which could plug the pipe and prevent safe release of the system pressure. If anyone is able to clarify this, please feel free to register and leave a comment or email us at

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Co2 is not 'supposed to blow the bloody doors off'


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UK:  In the words of Michael Caine in The Italian Job, we don't think the phrase 'you're only supposed to blow the bloody doors off' is what one Supermarket had in mind when a catastrophic failure of a Co2 refrigeration system occurred in one of their stores earlier this month.

Now a lot of engineers can be intimidated by CO2, and having seen these images I can probably understand why. And although these occurrences are extremely rare there are hazards that operatives should be aware of when working with high-pressure transcritical Co2 systems. I would guess this particular incident was a result of a manufacturing defect or pressure relief valve failure. Nevertheless, it could have resulted in a very serious injury or worse should someone have been in the vicinity at the time.

A recent post a saw on LinkedIn - What caused this? - When CO2 Goes wrong!! asked the question ‘could this be a lack of Operator / Engineer training’. Well without having the facts and not wishing to speculate, this does however pose a very poignant question. Should being in possession of a refrigerant handling (F-Gas) certificate qualify you to work with Co2 or indeed flammable refrigerants?

Time for mandatory regulation?

According to recent statistics released by the Environmental Agency there are now over 36,000 UK engineers that are F-Gas certified, any of which without having to have had any additional training, are deemed qualified to work with Co2 and flammable-based refrigeration and air conditioning systems.

With these new refrigerants now set to dominate the marketplace and the additional risks involved, I believe there is now a strong case for the industry to become better regulated and for engineers that are being requested to work on these systems to have received the necessary training through a recognised scheme, a similar way in which the Gas Safe scheme is operated.

This said and done I don’t see this will happen anytime soon if at all. In the meantime it’s left to the employer to ensure they fulfil their duty of care and provide adequate training in the safe operation and hazards involved when working with these refrigerants, for the health and safety of their employees.

Watch the Videos showing the aftermath - Transcritical Co2 refrigeration pack EXPLODED!!

Related Articles:

Emerson Climate Technologies - CO2 as a Refrigerant — Five Potential Hazards of R744


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ITALY:  Epta has announced the acquisition of Knudsen Køling, a company specialising in the design, installation and maintenance of turnkey refrigeration and CO2 systems in Denmark. 

Based in Køge, close to Copenhagen - Denmark, Knudsen Kølingand has been providing highly efficient refrigeration cabinets, plug-ins and reliable solutions to retailers for over 50 years, supported by a nationwide sales distribution and service network.

Epta is already present in the Nordic Countries with its own subsidiaries in Finland and Norway, working directly with major retailers, as well as through a premium network of qualified distributors. The Group entered into the agreement with the intent of consolidating its position in Northern Europe, one of the first markets to develop solutions with natural refrigerants. Epta and Knudsen Køling together, have already completed more than 1,000 installations of CO2 based refrigeration systems worldwide. The acquisition will foster important synergies among the existing operations in Germany and UK, with strong benefits for all customers and business partners in the region.

Marco Nocivelli, CEO of Epta remarked “Since the year 2000 Knudsen Køling has been one of the most dynamic players in Denmark in the development of CO2 systems. The acquisition of Knudsen Køling is a perfect match for our expansion plan to strengthen our presence in the refrigeration market worldwide, through partnership with leading brands in their respective countries. This is a great opportunity for both parties to share technological expertise and offer the widest portfolio of HFC free solutions”.


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EUROPE:  Carrier Commercial Refrigeration Europe has celebrated a landmark achievement having installed its 1,000th CO₂OLtec transcritical refrigeration system in a Kiwi store (Kiwi Laskentunet) in Norway.

Launched in 2004, the CO₂OLtec is now installed in a 1,000 sites in 19 European countries with Germany having the highest number of CO₂OLtec systems in operation, followed by Norway and Switzerland. The CO₂OLtec refrigeration system improves energy efficiency by an average of 10 percent compared with traditional hydro-fluorocarbon (HFC) systems in mild to cold climates. The energy savings, coupled with reliability and safety performance, have contributed to the success of CO₂OLtec technology.

Carrier has also developed the CO₂OLtec system to operate efficiently in warmer climates. “Carrier has made tremendous progress toward tearing down the former ‘CO₂ equator,’ thanks to new technological developments. A number of projects have been delivered in Spain and Italy, including a successful field trial of innovative controllable ejector technology,” said Christoph Brouwers, director, mechanical systems programs, Carrier Commercial Refrigeration, Europe.

The increasing popularity of Carrier CO₂OLtec product family, which includes small CO₂ condensing units to large indoor and outdoor refrigeration racks, means the CO2OLtec systems can provide solutions for applications ranging from small convenience stores and petrol stations, to hypermarkets and distribution centers.

The CO₂OLtec product family has been expanded further to include integrated systems designed to take control of a building’s thermal energy supply. These range from basic heat recovery for space heating or hot water systems, to fully integrated systems providing refrigeration, heating and cooling, ventilation and lighting control from a single source. CO₂OLtec integrated systems deliver up to 35 percent energy savings versus an equivalent R-404A system with a gas boiler, while reducing greenhouse gas emissions by up to 58 percent.

“We see more and more customers turning to natural refrigerant solutions for their refrigeration needs. At Carrier, the number of CO₂OLtec projects in operation has more than doubled over the past two years,” said Gunter von Starck, director, marketing, Carrier Commercial Refrigeration, Europe.

Carrier believes the operational benefits of Carrier’s CO₂OLtec system, combined with ongoing efforts by customers to reduce their carbon footprints, and the new European Union F-Gas (fluorinated gas) Regulation, mean that the CO₂OLtec success story is set to continue.

For more information about CO₂OLtec, visit

About Carrier 
Founded by the inventor of modern air conditioning, Carrier is the world’s leader in high-technology heating, air-conditioning and refrigeration solutions. Carrier experts provide sustainable solutions, integrating energy-efficient products, building controls and energy services for residential, commercial, retail, transport and food service customers.

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EUROPE:  High tech refrigeration and cold storage manufacturer Viessmann, has launched a new evaporator for the CO2 refrigeration market.

The new EWAP-CO2 coldroom evaporator, targeted at food retailers, wholesalers, and refrigeration contractors, is said to be quick to install due to its prefabricated anchoring points, and easy to both service and maintain thanks to Viessmann’s innovative design. 

Viessmann's TECTO Coldroom

The new Viessmann EWAP-CO2 evaporators come with cooling capacities ranging from 1.6 to 7.2 Kw, and can be specified to include up to four fans. 

Jim Whelan, director of international business at Viessmann says, “By using CO2 as the natural refrigerant, it means we are able to respond to the F gas regulation. EWAP, together with TECTO cold rooms are the future solution for retailers.”  Whelan went on to say, “The evaporator is a welcome addition to our innovative product range and we look forward to continuing to build our offering, using our trademark mix of market insight and technical product development techniques.”

About the Viessmann Group

The Viessmann Group is one of the leading international manufacturers of heating, cooling and climate control technology. Founded in 1917, the family business maintains a staff of approximately 11,400 employees and generates 2.1 billion Euro in annual group turnover. With 27 production divisions in 11 countries, subsidiaries and representations in 74 countries and 120 sales offices around the world, Viessmann is an internationally orientated company


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UK:  Blackpool-based Green Cooling has been appointed UK distribution partner of Italian CO2 refrigeration specialist Enex.

Italian manufacturer Enex, are recognised as being a leader in the design & manufacture of packaged CO2 refrigeration equipment and although CO2 based refrigeration systems are still far from becoming mainstream the market is experiencing significant growth.

Green Cooling's management team has extensive experience within both the CO2 and Hydrocarbon refrigeration sectors from both design and installation perspectives. This experience is driving the impressive growth of Green Cooling within the specialist area of natural and low global warming refrigeration.

The management of Enex feel that the specialist approach of Green Cooling, which is geared towards providing highly efficient refrigeration systems, with a low environmental impact, fits perfectly with the Enex range of CO2 equipment.

Green Cooling provides a complete service covering the design, specification, installation and commissioning of refrigeration systems across a wide range of critical applications. The Green Cooling management team have been working alongside the team at Enex for a number of years and this close relationship has now brought the two companies together in a formal distributor/manufacturer partnership.

Garry Broadbent of Green Cooling comments, "We are extremely pleased that we are now able to offer the Enex CO2 range on a formal UK distribution basis", continuing, "our approach is best practice driven and totally engineering focused which is completely aligned with the way Enex operate".

The Enex range includes low temperature -25°C and medium temperature 0°C packaged CO2 refrigeration pakaged units and also includes 80°C CO2 air & ground source heat pumps for the production of hot water.

About Enex

Enex specialises in the design and production of high-efficiency refrigeration systems using natural fluids. As a pioneer in the field of natural refrigeration, Enex has gained a remarkable experience in applications with CO2 as a refrigerant. Several hundreds of refrigeration systems of various types have been successfully installed over nearly 10 years. All design solutions developed by Enex are recognized for their quality, reliability and efficiency.


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UK:  Through working in partnership with Sainsbury’s, A-Gas has introduced a new carbon dioxide (R744/CO2) analysis and testing service in a move to improve the monitoring of CO2 refrigeration system performance. Ensuring moisture content and other impurities are kept within the recommended levels should be a key focus for everyone involved in the CO2 supply chain in the food production and supermarket industries.

A-Gas Managing Director John Ormerod said: “Natural refrigerants like CO2 are no different to traditional HFCs when it comes to quality. Ensuring CO2 supermarket systems operate within the strict boundaries of the correct moisture specification improves efficiency, reduces maintenance costs and saves money. During conversations with Sainsbury’s refrigeration technical specialist earlier this year, Sainsbury’s requested A-Gas’ expertise to help deliver a solution that would enable the monitoring of the quality of CO2 in their refrigeration systems and thus ensure reliability is maintained.”

Following successful tests with Sainsbury’s, A-Gas has now extended this analysis service to the rest of the HVAC industry. A-Gas provide customers with a suitably-rated cylinder in which they can supply a liquid sample from the refrigeration system. This is returned to A-Gas where it is tested in their state of the art laboratory and a full quantitative assessment is made. 

Sainsbury’s Head of Refrigeration John Skelton said: “This service enables Sainsbury’s to monitor that the quality of the refrigerant within our refrigeration systems is within the manufacturer’s specification ensuring the reliability and longevity of all components.”

Earlier this year, A-Gas launched a new high specification Carbon Dioxide (R744) refrigerant, eCO2. The refrigerant is produced sustainably from waste sugar beet, is UK-sourced, has excellent thermodynamic properties and is a green alternative to HFC gases like R404A, commonly used in these industries. With a moisture content of 5PPM, A-Gas’ eCO2 sets the CO2 standard for the future and is the driest CO2 available in today’s market. 

About A-Gas

A-Gas is a market leader in the supply of refrigerants within its core territories in the UK, Australia and South Africa, with modern state-of-the-art storage, blending and packaging facilities in Bristol, Melbourne and Cape Town. We are rapidly growing our market share in Asia and the Americas with sales offices in Singapore, China, Thailand and the USA.

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USA:  Danfoss has added higher maximum opening pressure differential (MOPD), UL approved BJ and BX coils to its existing product line. These higher MOPD coils are ideal for use with Danfoss AKVH electronic expansion valves to meet the rigorous demands of high pressure CO2 systems.

As part of a continuous effort to improve the North American CO2 product portfolio, Danfoss introduces six higher MOPD, UL approved BJ and BX coils. These new coils have larger pulling force which enables larger AKVH valves to operate in CO2 systems. Similar to the current BJ and BX coils on the market, these higher MOPD BJ and BX coils feature a redesigned frame and robust encapsulation, for extended lifetime and durability, as well as a clip-on fastening system with an audible latch click to minimize installation time and ensure proper installation of the coil.

The following specifications are based on the requirements of North American food retail systems.

Basic specifications:

  • Design in accordance with UL 429
  • Tested in harsh operating conditions from -40 – 122 °F
  • O-ring between coil and valve removed, for easy installation
  • Clip on function for secure connection
  • Redesigned frame, robust encapsulation
  • Covering standard voltage and frequency; two electrical connection versions

Advantages include:

  • Faster installation, without the use of tools, with clip-on function
  • More accurate installation with audible latch click
  • More reliable operation with durable frame and robust encapsulation
  • Widely available making logistics easier for the customer
  • Complete product portfolio of valve and coil combinations for a range of standard and alternative refrigerant needs

To View the Danfoss features video, Click here. 

About Danfoss: The Danfoss Group operates globally as one of the leaders in the manufacturing of components for the HVAC &R industry, power electronics, and mobile hydraulics. Their key competencies are cooling of food, air conditioning, control of electrical motors and heating in buildings – as well as solutions for renewable energy such as solar power. Danfoss employs 23,500 employees globally and has 110 sales companies around the world.

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UK:  BITZER has been manufacturing COcompressors since the mid 1990s and has now expanded its series of semi-hermetic refrigeration compressors for transcritical COapplications, including smaller and larger models. With the introduction of the 4PTC-6K model for lower displacements and the 4DTC-25K and 4CTC-30K models for higher displacements, the series now ranges from 4.3 to 25.6 cubic metres of displacement per hour at 50 Hz.

With CO2, only very small amounts of direct greenhouse gas emissions are released, so with these applications a greater focus is placed on reducing indirect emissions through energy consumption.  Consequently, BITZER CO2 compressors offer high energy efficiency and exceptional versatility.

BITZER is the only compressor manufacturer to also have its performance data certified by ASERCOM (Association of European Refrigeration Component Manufacturers). All compressors for subcritical COapplications, and most of the compressors for transcritical applications, have been integrated into the certification programme.

Further information is available from BITZER UK LIMITED, Advantage One, Third Avenue, Denbigh West, Bletchley, MK1 1DR, tel:  +44 (0) 1908 642966, fax:  +44 (0) 1908 644330, email: or downloadable from

USA:  There are in the region of 2000 transcritical CO2 systems operating worldwide in cold weather cities, and until now the southern most Hillphoenix Advansor transcritical CO2 booster system in North America was located in Chicago.

Hiilphoenix have now developed a new hybrid system for Sprouts Farmers Market's new store in Dunwoody, Georgia that will run on an Advansor transcritical booster system.

"We worked with Baltimore Air Coil to develop a new product that's a hybrid evaporative condenser adapted for use with CO2," said Scott Martin, director, sustainable technologies at Hillphoenix. "Evaporative condensers offer energy savings by providing lower system condensing temperatures than conventional air-cooled or water-cooled condensing systems."

Retailers and engineers in North America have widely questioned whether a CO2 transcritical system, could be operated efficiently in areas where the ambient temperature climbs above 85 ºF. Energy efficient, economical transcritical CO2 refrigeration systems are normally limited to colder climates due to the limitations of air-cooled gas coolers. The key to Sprouts' new system is a proprietary TrilliumSeries™ hybrid evaporative condenser designed for Hillphoenix by Baltimore Air.

With its new Dunwoody store, Sprouts aims to change the industry's preconceived perceptions about warm climate operation of transcritical CO2 systems, demonstrating that it is a viable option for retailers seeking a more sustainable, energy efficient refrigeration option.

"Central to Sprouts' identity is a genuine commitment to responsible retailing," said Ted Frumkin, senior vice president of business development, Sprouts Farmers Market. "This innovative partnership with Hillphoenix helps Sprouts reduce waste and our environmental impact, which we know is important to our customers and our team members."

About Hillphoenix: Hillphoenix Inc., a Dover Company is based in Conyers, Ga. The company designs and manufactures commercial refrigerated display cases and specialty products, refrigeration systems, integrated power distribution systems and walk-in coolers and freezers. Visit or call 800-283-1109 for more information.

About Sprouts: Recently named one of the top five supermarket chains by Consumer Reports and headquartered in Phoenix, Arizona, Sprouts employs more than 15,000 team members and operates more than 175 stores in ten states.