SAE publishes 18 standards on new A/C refrigerant HFO-1234yf

  • 15-Feb-2011 09:11 EST
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This prototype of Neutronics' identifier plugs into a J2843 recovery/recycle/recharge machine’s USB port to ensure that the vehicle system contains HFO-1234yf before the recovery step to prevent refrigerant cross-contamination.

A suite of 18 new or revised engineering standards to support the industry’s forthcoming phase-in of the low-global-warming A/C refrigerant HFO-1234yf has just been published by SAE International. The huge undertaking, following an SAE Cooperative Research Group study that indicated suitability of the chemical in 2009, was the effort of work groups in the Interior Climate Control Standards Committee, which represented all segments of the industry.

The standards, which will soon be accompanied by the U.S. EPA’s posting of HFO-1234yf as a “SNAP List” refrigerant, cover refrigerant purity and safety; components design; engineering measurements; service equipment; and technician training. The first vehicles with this refrigerant are expected later this year, shortly after HFO-1234yf production quantities become available. The current refrigerant, R-134a, will continue to be used as HFO-1234yf is phased in.

Although many of the standards had been completed over the past year, the entire group was held for a single release because there is considerable cross-referencing. Indeed, SAE J2911, an umbrella standard that specifies how certification to many of the other standards is obtained, was approved by SAE Motor Vehicle Council in early February.

HFO-1234yf-equipped automobiles and any light trucks are likely to be sold first in Europe. Introduction schedules had been juggled to be in compliance with a European Community regulation that mandates a change to a refrigerant with a low-global-warming number (150 and below) on all “new type” vehicles introduced starting Jan. 1. However, HFO-134a can be installed in “existing” vehicles produced through 2017.

There are EPA “carbon credits” for using HFO-1234yf in U.S.-market vehicles, but a changeover is not regulatorily mandated at this time, nor is it in Asia. General Motors Corp. is the only U.S. automaker to announce introduction of the refrigerant (for the 2013 model year, which starts Jan. 1, 2012). It has a supply contract with Honeywell.

EPA “SNAP” listing

The completion of the suite enables the federal Office of Management and Budget (part of the Executive Office of the President) to sign off on an EPA-approved “SNAP” listing, knowing that the industry is ready. The SNAP (Significant New Alternatives Policy) list was developed by the EPA under the Clean Air Act mandate to regulate alternatives to CFC-12 (R-12), the long-used chlorofluorocarbon refrigerant phased out in the early 1990s as a stratospheric ozone-depleting substance. CFC-12 also had a high-global-warming number (contributive effect to global warming) of 12,000 vs. 1430 for R-134a and just 4 for HFO-1234yf. At the time, that reduction from the changeover to R-134a was considered a serendipitous bonus (but by today’s standards, insufficient), as the hole in the ozone layer was the primary international concern.

Both R-134a and HFO-1234yf are chemicals called hydrofluorocarbons (HFCs) composed of hydrogen, fluorine, and carbon, but HFO-1234yf is in a special category called a hydrofluoro olefin (HFO), which means it has a double bond of the carbon atoms.

A refrigerant can be used in the U.S. only if it is on the EPA SNAP list, which may include restrictions (such as safety requirements) on the system in which it’s installed.

Replacements for CFC-12 have no stratospheric ozone-depletion characteristic. But all auto A/C refrigerants, from CFC-12 to the alternatives, by law must be recovered and recycled (using equipment certified to SAE standards) or destroyed, when systems are serviced by professional technicians. The technicians must pass certification tests to demonstrate education on this issue, and they are required to use equipment certified to applicable SAE standards.

Regulatory agencies at the state and federal level typically reference SAE standards where applicable, and much advance work by EPA and industry groups set the table for HFO-1234yf, which represents the first OE use of a flammable automotive refrigerant. However, flammability of HFO-1234yf is minimal, and it carries a new ultralow-flammability rating by the Air Conditioning, Heating, and Refrigeration Institute. So with engineering precautions it can be used in a direct expansion system (evaporator in passenger compartment) vs. more flammable refrigerants that for safety must be confined to an underhood loop, which increases complexity and reduces efficiency.

Concerning costs

Because Honeywell holds recently issued patents, there are only two identified sources of HFO-1234yf: Honeywell and DuPont. HFO-1234yf is a long-known chemical and there is prior patent art for it as an A/C refrigerant dating back to 1992. The Honeywell patents are the subject of legal action in Europe and the U.S. But carmakers’ need for HFO-1234yf to meet European regulatory requirements led to acceptance of the refrigerant sourcing limitations. The refrigerant is known to be expensive to make, and prices for large quantity purchases with long-term contracts are believed to be $90-100/kg ($40-45/lb), which has led to estimates of perhaps $155/kg ($70/lb) at the service shop wholesale level and $220/kg ($100/lb) as a retail price. Although carmakers would welcome additional sources, they would not lead to a price close to R-134a's. Although a recent (and likely short-lived) spike brought R-134a prices to $26.45/kg ($12/lb) for purchases by the 30-lb tank, prices over the past year have averaged about $14.55/kg ($6.60/ lb).

Further, R-134a is nonflammable and more efficient, so to match performance an HFO-1234yf system needs an additional heat exchanger (called an “IHX”—internal heat exchanger). For safety, it requires an upgraded evaporator, referenced by SAE J2842. Although R-744 (carbon dioxide used as a refrigerant) is not intended for production now, it was covered in this standard for possible guidance to future development.

The total cost of a changeover, estimated at under $100, is considered moderate for the value of the carbon credits for those companies that wish to have these credits for their vehicle fleet. The credits translate to numerical help with the 35.5 mpg required to meet federal corporate average fuel economy regulations by 2016. An earlier conversion provides advance credits for carmakers.

The cost of HFO-1234yf makes it likely that it will be used primarily for OE installations and warranty service. Following that, customer-pay sales could well be minimal, except for small amounts. The new systems are very tight, and most should go 7-8 years or more before leakage creates a performance problem. Further, carmakers and Tier 1 suppliers have worked for years to produce more efficient heat exchangers and refrigerant line routings that reduce the required refrigerant charge. R-134a systems once held 3-4 lb (850-1135 g), in some cases even more. Today, there are many R-134a systems with capacities of under 18 oz/500 g (as low as 11.7 oz/330 g). Similarly low or lower charges with HFO-1234yf would reduce OE cost.

Unless EPA is directed to rule otherwise, R-134a, HFO-1234yf, and 12 other refrigerants on its SNAP list would be equally legal for use as “retrofit” refrigerants. After warranty, it is recognized that some percentage of HFO-1234yf systems will leak earlier in their service life. When the motorist is paying, a leaking HFO-1234yf system could be repaired and changed over to lower-cost R-134a, with no effect on performance or durability. Other SNAP refrigerants also might be used in HFO-1234yf systems, with uncertain effects, as the listing covers environmental, toxicity, flammability, and other safety factors, not cooling performance, durability issues, etc. Any cross-contamination of refrigerants in systems and service equipment is an industry concern.

SAE J2888 fittings would prevent inadvertent mixing of refrigerants, but adapters to enable an intentional changeover are expected to appear. As a result, new HFO-1234yf recovery/recycle/recharge machines will be engineered with refrigerant identifiers to ensure the system being serviced truly contains the new refrigerant, before recovery can begin. The identifiers (certified to SAE J2927) either are built in or plug in to a USB port (so one identifier can be used with multiple machines in a large shop).

The new and revised standards are:

• J639_201102 Safety Standards for Motor Vehicle Refrigerant Vapor Compression Systems

• J2064_201102 R134a Refrigerant Automotive Air-Conditioned Hose

• J2099_201102 Standard of Purity for Recycled R-134a (HFC-134a) and R-1234yf (HFO-1234yf) for Use in Mobile Air-Conditioning Systems

• J2297_201102 Ultraviolet Leak Detection: Stability and Compatibility Criteria of Fluorescent Refrigerant Leak Detection Dyes for Mobile R-134a and R-1234yf (HFO-1234yf) Air-Conditioning Systems

• J2670_201102 Stability and Compatibility Criteria for Additives and Flushing Materials Intended for Aftermarket Use in R-134a (HFC-134a) and R-1234yf (HFO-1234yf) Vehicle Air-Conditioning Systems

• J2762_201102 Method for Removal of Refrigerant from Mobile Air-Conditioning System to Quantify Charge Amount

• J2772_201102 Measurement of Passenger Compartment Refrigerant Concentrations Under System Refrigerant Leakage Conditions

• J2773_201102 Standard for Refrigerant Risk Analysis for Mobile Air-Conditioning Systems

• J2842_201102 R-1234yf and R744 Design Criteria and Certification for OEM Mobile Air-Conditioning Evaporator and Service Replacements

• J2843_201102 R-1234yf [HFO-1234yf] Recovery/Recycling/Recharging Equipment for Flammable Refrigerants for Mobile Air-Conditioning Systems

• J2844_201102 R-1234yf [HFO-1234yf] New Refrigerant Purity and Container Requirements for Use in Mobile Air-Conditioning Systems

• J2845_201102 R-1234yf [HFO-1234yf] and R-744 Technician Training for Service and Containment of Refrigerants Used in Mobile A/C Systems

• J2851_201102 R-1234yf [HFO-1234yf] Refrigerant Recovery Equipment for Mobile Automotive Air-Conditioning Systems

• J2888_201102 HFO-1234yf Service Hose, Fittings, and Couplers for Mobile Refrigerant Systems Service Equipment

• J2911_201102 Procedure for Certification that Requirements for Mobile Air-Conditioning System Components, Service Equipment, and Service Technician Training Meet SAE J Standards

• J2912_201102 Performance Requirements for R-134a and R-1234yf Refrigerant Diagnostic Identifiers for Use with Mobile Air-Conditioning Systems

• J2913_201102 R-1234yf [HFO-1234yf] Refrigerant Electronic Leak Detectors, Minimum Performance Criteria

• J2927_201102 R-1234yf Refrigerant Identifier Installed in Recovery and Recycling Equipment for Use With Mobile A/C Systems

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