Codes and Standards for low-GWP Refrigerants

by Mark Menzer

As I write this, President Trump is signing an executive order to roll back the Obama Climate Initiative.  Will this change of policy mean that the HVACR industry’s move to new, low-GWP refrigerants is ending? Not at all. The industry continues to phase down the use of HFCs.  We are testing new refrigerants and continue to redesign equipment to accommodate them.  Equipment manufacturers are driven by a domestic and global market which is demanding a move away from HFCs like R-134a and R-407A which are potent greenhouse gasses.  So, with or without leadership from Washington, the trend continues.

We are moving from the current use of ASHRAE type A1 refrigerants (non-flammable) to A2L (flammable with low burning velocity, meaning that it is difficult for a flame to sustain itself) and to A3 refrigerants (higher flammability).

Over the past two years, the EPA has issued rules that will phase out certain HFCs in most applications.  Some of the rules, under the Significant New Alternatives Policy (SNAP) have already taken effect and more will be coming into force over the next seven years.  We cannot expect that any of the regulations already issued will be withdrawn in the current administration.  So, we need to continue to work to safely accommodate equipment that will use the new refrigerants.      

As most are aware by now, many of the new generation of low-GWP refrigerants are flammable. We are moving from the current use of ASHRAE type A1 refrigerants (non-flammable) to A2L (flammable with low burning velocity, meaning that it is difficult for a flame to sustain itself) and to A3 refrigerants (higher flammability). These changes increase the risk for the contracting community.  Contractors that install, maintain and service equipment should be preparing now for this change and for other recent EPA rule changes.

What Can be Done to Lessen the Risk?

Groups of industry experts have been working diligently to develop safety standards that will require additional measures to reduce the possibility of refrigerant escaping from HVACR equipment and, if it should escape, to make sure it does not reach a combustible concentration.  The main application safety standard in North America is ASHRAE 15.

ASHRAE Standard 15, Safety Standard for Refrigeration Systems, is on continuous maintenance, meaning that changes can be proposed at any time.  The committee is working to have the addenda concerning flammable refrigerants completed before the end of 2017, so that the changes can be considered for the next editions of the model codes.

ASHRAE 15 will contain measures that limit the chance for ignition of a refrigerant.  Combustible gasses have a limited range in which they can ignite.  Too little gas mixed in air will not ignite nor will too high a concentration.  For propane, for example, a mixture of less than 2% will not ignite.  So, engineers simulate leaks using complex computer aids called computational fluid dynamics (CFD).  These graphical simulations show how leaked refrigerants mix with air and how likely they are to reach a flammable concentration.  Then, using a conservative safety factor, they estimate how much refrigerant should be allowed in that equipment such that a leak will not lead to a flammable mixture.  All this helps determine a maximum safe charge limit for equipment.

In addition to specifying equipment charge limits, the safety codes may also call for refrigerant leak detectors. These detectors, much like carbon monoxide (CO) detectors, may shut down the system in the event of a leak and will also turn on a ventilation fan assure that a combustible mixture does not form.

In addition to specifying equipment charge limits, the safety codes may also call for refrigerant leak detectors. These detectors, much like carbon monoxide (CO) detectors, may shut down the system in the event of a leak and will also turn on a ventilation fan assure that a combustible mixture does not form.

Further, for many applications, manufacturers and installing contractors may be required to use spark-free switches and other controls, so as not to provide a source for ignition.  For larger systems or those with long refrigerant lines, there may be requirements for automatic valves, so that parts of the system can be isolated and most of the refrigerant can be contained, in the case of a rupture.

ASHRAE Standard 15 is an application standard, providing rules for the installation of HVACR equipment.  There are also equipment safety standards.  In North America, they are usually UL or CSA standards.  These standards are also undergoing revision currently. The second and third editions of UL Standard 60335-2-40 — Requirements for Electrical Heat Pumps, Air Conditioners and Dehumidifiers — are being developed to include requirements for A2 and A3 refrigerants (Edition 2) as well as A2Ls (Edition 3).

The model codes are where safety standards, like ASHRAE Standard 15, become part of an enforceable document.  The major safety codes for HVACR applications are the International Mechanical Code, the International Residential Code and International Fire Code (all issued by the International Code Council) and the Uniform Mechanical Code (issued by IAPMO).  These are the codes that are eventually adopted by most states and localities, although there are a few exceptions.  These model codes could be available for adoption by states as early as 2021.  Unfortunately, experience has shown that some states take six years or more to adopt the latest model code, so it could be a while before the changes are nationwide.

New EPA Rules

Both current and new refrigerants are also affected by changes to the EPA rules for refrigerant management. These are called Section 608 Rules after that portion of the Clean Air Act that required EPA to oversee the handling and recycling of refrigerants. 

Both current and new refrigerants are also affected by changes to the EPA rules for refrigerant management. These are called Section 608 Rules after that portion of the Clean Air Act that required EPA to oversee the handling and recycling of refrigerants.

Many of the EPA changes take effect in 2018.  Starting next year, only EPA certified technicians can open HFC equipment (until now that has only applied to CFC and HCFC equipment), they must use certified recovery and recycling equipment when doing so, and only certified technicians can purchase HFC refrigerants.

In 2019, the leak reporting and repair requirements become more stringent.  For example, the leak rate must be calculated for any equipment using more than 50 pounds of refrigerant every time refrigerant is added to the equipment.  The threshold at which leaks need to be repaired will be decreased.  For commercial refrigeration, the threshold moves from 35% leakage per year to 20%.  Products that have had a history of leaking may be subject to a periodic inspection regimen.

EPA has an excellent overview of all the recent updates to the Refrigerant Management Program. YOU CAN FIND THE OVERVIEW HERE.

Research on Flammable Refrigerants

At the same time, in a major coordinated research push unlike the industry has ever seen, AHRI, ASHRAE, the California Air Resources Board and the US Department of Energy, along with in-kind contributions from UL, are providing funding of $5.2 million dollars to assess the effects of using flammable refrigerants and how to minimize their risks. The research ranges from conducting a risk assessment of leaks to surveying the availability of leak detection equipment to assessing field-made mechanical joints for their proneness to leaks. The results of this research will feed into the continuing development of safety standards.

What Can You Do?

Meanwhile, equipment using flammable refrigerants are starting to appear in North American markets.  Contractors should become aware of the EPA rules concerning new refrigerants. This is a good time to train technicians on the same handling of flammable refrigerants. Encourage your state and local governments to quickly adopt the latest safety codes, so that you have the opportunity to safely install the next generation of HVACR equipment.  

The regulatory train may have slowed in Washington, but the move to new refrigerants continues.