SAE standards point way to service of R-1234yf systems

  • 29-Feb-2016 12:37 EST
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SAE J2843-compliant machines (R-1234yf) require satisfactory refrigerant identification to enable recovery. The identifier may be built-in, or hand held with a USB cable connection to the machine, as shown.

The automotive air-conditioning industry changeover to low global warming R-1234yf involves a lot more than new fittings and a more robust evaporator to prevent leakage of the mildly-flammable refrigerant. An initial group of new A/C-related SAE standards was promulgated last year (http://articles.sae.org/9392), and several others are going through the development pipeline including SAE J3094, a test procedure to verify performance of internal heat exchangers.

And as part of the cooperative process with EPA, the agency's Rebecca von dem Hagen told a recent meeting of the SAE Interior Climate Control Standards Committee that three of them will be incorporated in EPA regulations by reference. They are SAE J2843, which covers recovery, recycling and recharging (RRR) equipment for flammable refrigerants; SAE J3030, a new standard for RRR both R-134a and R-1234yf with a single machine —the two refrigerants that are in simultaneous use; and J2851, which defines requirements for recovery-only equipment for systems containing contaminated R-134a or R-1234yf.

They join SAE J2788, a standard for high-efficiency recovery, recycling and high-accuracy recharging of R-134a, which has been referenced in the U.S. Clean Air Act since 2007.

SAE J2843 differs from J2788, the standard for R-134a-only RRR equipment, in that it sets engineering requirements for safety of flammable refrigerants, including anti-arcing switches, motors and solenoids, and venting the interior of a machine to remove refrigerant vapors that might otherwise accumulate.

Refrigerant ID now needed

It also introduced the requirement for refrigerant identification, so an identifier must be built in or the machine be equipped with a USB port to accept an ID signal from an identifier connected to the vehicle being serviced. If the signal does not indicate a sufficiently-pure refrigerant charge, the machine will not enable recovery.

At the conclusion of recovery and recycling, the machine will perform a vacuum decay test for gross leakage from the system. If there is a gross leak, the machine will permit only a 15% charge of R-1234yf to enable the technician to use an electronic detector to pinpoint the leak. The purpose of this test is to ensure that the system is reasonably leak-free prior to a recharge, both for environmental benefit and to avoid wasting the expensive refrigerant.

SAE J3030, published in late 2015, provides two equipment choices for the service industry during the period when both refrigerants will be used. This will save many shops from having to invest in two pieces of equipment. SAE J3030 combines the requirements in the J2843 and J2788 standards and adds a cross-contamination test, ensuring that use of the machine in R-134a or R-1234yf mode will not result in cross-contamination of the refrigerant in any vehicle system.

The standard is unique in that it allows two engineering approaches. First, a machine that can go back and forth between the two refrigerants in shop operation (with refrigerant identification for each mode).  Or second, the machine can start with dedication to one refrigerant (R-134a as the obvious choice) and when service volume is sufficient, the shop can make a one-time, permanent conversion to service only R-1234yf.  It then would, of course, need another machine to continue R-134a service.

The standard requires that the conversion be tamper-resistant and that refrigerant identification is incorporated. This second arrangement permits the shop to make a lower initial investment in equipment that will not become obsolete, although restricted to either-not-or RRR of R-134a and R-1234yf. The shop also would be able to delay purchase of a compliant refrigerant identifier until needed for R-1234yf.

SAE J2851, also a recent publication, is for recovery-only equipment that will collect contaminated R-134a and/or R-1234yf. It enables shops to service vehicles with refrigerant identified as unsuitable for recovery with an RRR machine. J2851 requires 95% recovery efficiency at shop temperatures (70-75° F/21-24°C), 85% at moderate outdoor temperatures (10-13°C/50-55° F)

'Groundbreaking' SAE J2911 in revision

Undergoing revision is the groundbreaking SAE J2911. This standard requires marketers of R-134a/R-1234yf service equipment and aftermarket evaporators for R-1234yf that claim compliance with SAE standards and/or use the compliance labeling on their products, to post the laboratory data on the macdb.sae.org  website.

The revision will define which version of a standard must be used during testing. The website includes a way for anyone who disputes performance claims to issue a formal challenge to the manufacturer, initiating a sequence that can force the manufacturer to prove them.

Still in development is SAE J3094, a test procedure to verify performance of internal heat exchangers (IHX). These devices carry an EPA Corporate Average Fuel Economy (CAFE) credit. Although used on only some R-134a systems, they are to date across the board on R-1234yf systems.

The standard will contain tests to confirm IHX heat transfer performance, by using pressure and temperature measurements at each end of the IHX, at specified refrigerant mass flow, with and without oil in circulation.

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