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Carbon Dioxide (R744/CO2) as as Refrigerant Code of Practice

2009 (revised 2013)


Buy the Codes now and be sent the free update when the Codes are revised in line with the new EN3878 Safety Standard which is expected to be published later in 2016.


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Some of the risks presented by the use of carbon dioxide are different from risks presented by the use of other refrigerants. Methods of use may also differ. Systems using carbon dioxide can be designed to minimise risk but special care is needed to take into account the properties of carbon dioxide. Such systems are now within the scope of legislation under the Pressure Systems Safety Regulations 2000 (PSS Regulations) which stipulate requirements to be met by designers, suppliers, installers and users. The Pressure Equipment Directive 97/23/EC (PED) implemented in the UK by the Pressure Equipment Regulations 1999 (PER), places duties on anyone who designs, manufacturers or supplies pressure equipment and assemblies with a maximum allowable pressure greater than 0.5 bar.  This Code reflects the requirements detaied in the refrigeration Safety Standard BS EN 378:2008.

2013 Amendmen

The IOR Technical Committee has issued an amendment to its Safety Code of Practice for Carbon Dioxide Refrigeration Systems related to the Pressure Systems Safety Regulation requirements, which should be brought to the attention of those responsible for the ownership, operation, installation or design of relevant systems.  

Owners of carbon dioxide (R744) vapour compression refrigeration system incorporating compressor drive motors, having a total installed power not exceeding 25kW may consider that they are, by way of exception 18 of schedule 1 of the Pressure Systems Safety Regulations 2000 (PSSR), exempt from the regulations.  Generally CO2 systems operate at pressures higher than 40 Bar and consequently incorporate pressure vessels with large amounts of stored energy.

Such systems would fall into the intermediate category of the PSSR were it not for this exemption. Owners / users should be aware that the Health and Safety Executive have confirmed that articles 5 & 6 of the Provision and Use of Work Equipment Regulations 1998 (PUWER) place the maintenance and inspection of all equipment (including systems) as an obligation on the owner.

The Institute of Refrigeration recommends that if a system contains any vessel where the product of the internal volume (litres) x the allowable pressure (Bar) is greater than 250 bar litres owners/users should work to the principles of the PSSR and follow the guidance given in PSSR Approved Code of Practice ISBN 978 0 7176 1767 8 which is available as a free to download publication at

Amendment and Revision Schedule for IOR Codes

From time to time the IOR Technical Committee may need to issue updates or addendum to this Code, register for IOR news updates to ensure you are kept informed of any changes. IOR Codes of Practice are subject to revision in line with the schedule for publication and revision of BS EN 378 Safety Standards.

IOR Members 

Members of the IOR receive free each year a copy of all of the IOR Refrigerant Codes of Practice including the Carbon Dioxide Code and updates, on a member-only CD-rom.  If members wish to purchase additional copies of the Code for business use via this website a reduced member fee is offered (please log in to see the discounts).


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