Exclusive interview with R. Haseman, UL Standards - CO2 update

By Alexandra Maratou, Feb 22, 2013, 13:00 3 minute reading

Following the December 2012 announcement by one US-based company that its CO2 booster refrigeration system had received UL listing under a special submission, R744.com talked to Randall Haseman of Underwriters Laboratories (UL) to get an update on the latest and upcoming developments regarding CO2 certification requirements in North America.

R744.com: UL LLC is currently developing requirements for the use of CO2 in centralised transcritical commercial refrigeration systems. When do you expect to finalise these?

Randy Haseman: The primary safety concern with using CO2 as a refrigerant in a transcritical system is the relatively high working pressure. The refrigerant containing components have to be able to withstand this pressure, and an evaluation must be conducted. Building on existing “fatigue” testing requirements for other high-pressure refrigerants, UL has developed additional requirements specific to CO2. These requirements will be published as Certification Requirement Decisions (CRDs) for the affected standards in early 2013. CRDs are UL’s certification requirements applied in advance of their appearance in the published standard. The requirements will then be proposed as standards revisions and typically published in the standard within 3-6 months of being proposed.

R744.com: In the meantime, one US based company announced in December 2012 that under a special submission, its CO2 booster refrigeration system had received UL listing in both the US and Canada.
    a. Would you encourage other manufacturers to follow the path of special submission, until the certification requirements are finalised?
    b. Has this special project enabled you to crystallise the certification requirements?

RH: Yes, of course we would encourage other manufacturers to apply for UL Certification of their CO2 product. This latest project was one of several that helped UL develop additional CO2 requirements. Several years ago we published requirements for subcritical CO2, and since then we have had several manufacturers work with us on smaller self-contained transcritical systems. These all helped in the development of the current certification requirements. You may also be interested in knowing that several refrigerant motor-compressor manufacturers have received UL Certification on their CO2 motor-compressors. Over time, we expect more CO2 motor-compressors to be certified which will in turn enable various sizes of CO2 systems to also be certified.

R744.com: In what way could these new UL requirements enable the uptake of CO2 transcritical technology by North American supermarkets?

RH: Published requirements and UL Listing makes it much easier for products to gain acceptance by supermarket owners, designers, and inspection authorities.

R744.com: Could you already provide R744.com readers with a preview of some of the main requirements for centralised commercial refrigeration transcritical CO2 systems that you expect to be included in UL standards?

RH: As you know, one of the primary safety concerns with using CO2 as a refrigerant in a transcritical system is the relatively high working pressure. The traditional method of evaluating a refrigeration component is to conduct a strength test at 5 times the normal working pressure. A CO2 component complying with this requirement would need to be relatively large, thick and heavy as compared to components used with the more traditional refrigerants. As a result, an alternative “fatigue” test was developed. The fatigue test cycles components between a high and low pressure for 250,000 cycles to simulate a lifetime of use. The components are then strength tested at a pressure that is lower than the pressure used in the traditional method, but because of the fatigue conditioning, an equivalent level of safety is achieved.

R744.com: Does UL intend to develop requirements for CO2 technology for other applications (i.e. heat pumps etc) in the near future, or update existing ones?

RH: The CO2 requirements are intended to be “horizontal”, in that they may be used for virtually any refrigeration and air conditioning products. When a particular industry segment shows an active interest, we can take steps to publish the requirements in that particular standard. Note UL is also looking at the existing IEC pressure requirements for self-contained CO2 transcritical systems and intend to propose these as another testing option.

R744.com: How could the industry be of assistance to UL’s work?

RH: Continue to actively participate in UL’s Standards Technical Panels (STPs). These are UL’s standards development committees, consisting of producers, standards users, inspection authorities, consumers, and others with an interest in the standard. Members of STPs initiate, review, comment, and vote on standards revisions and proposals.



By Alexandra Maratou

Feb 22, 2013, 13:00

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