There is a high level of concern about safety in the HVACR industry. Changes in code, standards and fire safety may involve adoption of new set of refrigerants and redesigning the equipment. UL established a Flammable Refrigerant Joint Task Group, as the risks associated with refrigerants require focused mitigation schemes to ensure their safe use. One such risk is flammability, as defined by ASHRAE 34 for Class 2L, 2 and 3 refrigerants. A2L refrigerants are classified as flammable at 600C, so one way is improve the evaporation.
Refrigeration and AC in everyday life
Briefly to put, supermarkets demands are huge for refrigeration and AC. Grocery stores keep the food chilled for customers. Restaurants store food until ready to be cooked. Food is delivered at proper temperatures in reefer trucks. Surgeons operate in air-conditioned hospitals and people travel in air-conditioned cars and trains. Chilled vaccines and medicines are delivered safely to those in need.
The number of room air conditioners is set to triple to over 4.5 billion globally by 2050. A new report commissioned for EIA found that a shift away from HFCs in domestic split AC systems supported by updated product standards could avoid emissions of over two gigatonnes CO2-equivalent by 2030 and 5.6 gigatonnes CO2e by 2050.
Refrigerants emission-a global concern
Global concerns in terms of refrigerant emissions relate with the term anthropogenic – referred as the current geological age. It is viewed as the period during which human activity has been the dominant influence on climate and the environment.
Nobel laureate Paul Crutzen, known for work on climate change research popularized the term Anthropocene. He and his colleagues demonstrated that substances used in refrigeration and other applications depleted the ozone layer. Consequently, nations of the world together, signed Montreal Protocol in 1987, signed by 197 countries: an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. In 2016, Parties to the Montreal Protocol adopted the Kigali Amendment to phase down production and consumption of hydrofluorocarbons (HFCs) worldwide. The goal was to reduce consumption of HFCs by 80% over 30 years.
Former US President Ronald Reagan stated, “It is a model of cooperation. It is a product of the recognition and international consensus that ozone depletion is a global problem, both in terms of its causes and its effects. The protocol is the result of an extraordinary process of scientific study, negotiations among representatives of the business and environmental communities, and international diplomacy. It is a monumental achievement.”
Toxicity and Flammability of refrigerants:SNAP
Exposure limits set for all chemicals are based on chronic toxicity concerns. Lower flammability limit (LFL) and upper flammability limit (UFL) for all flammable gases and vapors define the range of flammable concentrations in air. Information on the toxicity and flammability of refrigerants is available from Significant New Alternatives Policy (SNAP) substitute risk screens, chemical manufacturers, published literature, and safety data sheets for all chemicals. SNAP was established under Section 612 of Clean Air Act to identify and evaluate substitutes for ozone-depleting substances.
Toxicity: The risks associated with the use of refrigerants in refrigeration and air-conditioning equipment include toxicity, flammability, asphyxiation, and physical hazards. An ideal refrigerant would be nontoxic, nonflammable, completely stable inside a system, environmentally gentle, and easy to manufacture. It also would be self-lubricating. The likelihood of developing an ideal refrigerant is low.
It is important to mitigate and reduce both acute and chronic risks to ensure safe use of all refrigerants. Refrigerant leak detectors and monitoring systems are used to identify and warn technicians for toxicity concentration increases. Acute toxicity impacts short-term exposures, often at high concentrations and is also a test for service operations, such as upon opening a compressor. Chronic toxicity is the effect of repeated exposures over a long period. Few technicians actually spend their full day in machinery rooms and concentrations may fluctuate. The occupational safety measures may be used to minimize their impacts.
Flammability: As known, flash point and vapor pressure contribute to the flammability and the flash point of a substance is the lowest temperature at which it can vaporize to form an ignitable mixture in air, while the vapor pressure indicates evaporation rate. Higher vapor pressures lead to lower flash. points and therefore higher flammability.
Standards and safety classification
ASHRAE 15, Safety Standard for Refrigeration Systems, establishes procedures for operating equipment and systems when using refrigerants. The current approach to limiting the hazard associated with 2L, 2 and 3 refrigerants in codes and standards is based on two main principles: limit the refrigerant charge, or detect and then ventilate the space when a leak has been detected.
The ANSI/ASHRAE 34 (Designation and Safety Classification of Refrigerants) and ISO 817 (Refrigerants – Designation and safety classification) standards each have a safety group classification system for refrigerants based on toxicity and flammability data.
The current approach to limiting the hazard associated with 2L, 2 and 3 refrigerants in codes and standards is based on two principles: limit the refrigerant charge, or detect and then ventilate the space when a leak has been detected.
– A1 (No Flame propagation) has Freon type refrigerants: R-22, R-134a, R-410A etc., most used.
– A2L (HVAC industry defined mildly flammable) recently developed refrigerants are classified as flammable at 600C. An example is R-1234yf, an HFO used as a replacement for R-134a in automotive air conditioning. Another is R-32 replacement for R410-A, used for air conditioning in markets outside US.
– A3 (HVAC industry defined highly flammable) like odourless propane and isobutene.
Due to continuing concerns about using the more flammable refrigerants in equipment requiring larger charge sizes (notably, air-conditioning equipment), the A2L refrigerant class receives increased attention.
Update Safety Standards and codes for Flammable Refrigerants
ASHRAE 15; ASHRAE 34; and the third edition 2019 of UL 60335-2-40 – Standard for Safety for Household and Similar Electrical Appliances – Safety requirements and risk mitigation for A2L Refrigerants – which is currently in survey phase with UL Standards Technical Panel, proposes to increase the charge limits for A2L refrigerants.
UL standard 2683 for HVAC Industry: To keep pace with new technology and help simplify product safety requirements for manufacturers, UL announces UL 2683, a new standard – the Standard for Electrical Heating Systems for Floor and Ceiling Installation. UL 2683 not only supersedes the legacy standards but also includes newly developed requirements for current trends in heating systems technology. During the transition period to UL 2683, the existing legacy Standards may still be used to support product certifications. As of October 1, 2022, UL plans to use UL 2683 for all new products covered by the scope of this Standard.
AHRI Research to update safety
The HVACR industry is transitioning to low GWP refrigerants due to environmental concerns and regulatory requirements. Many of these low GWP refrigerants are classified as lower flammability which require the update of relevant safety standards and codes to implement these in the field. AHRI has been leading a $ 6 million plus research program was jointly funded by AHRI, ASHRAE, CARB and US Department of Energy. The goal of the research initiative is to deliver scientific findings and produce publicly available technical references to support code and standard activities related to the use of flammable refrigerants.
Underwriters Laboratory and the ASHRAE along with stakeholders, including industry experts have worked to update the safety standards. AHRI surveyed 46 relevant safety standards’ committees related to flammable refrigerants for technical data gaps. High priority projects were identified and initiated to understand the refrigerants flammability risk, refrigerant charge quantity, refrigerant detector technologies, mitigation effectiveness and equipment installation.
Amend codes to use flammable refrigerants
Organizations like AHRI and UL have researched the usability of flammable refrigerants for years.
Karim Amrane, Ph.D.,owner and president of KA Consulting Services, LLC, was senior vice president, regulatory and international policy for AHRI, and he says, the greatest challenge will be amending codes quickly enough to use the flammable replacements. “So, ‘even if I want to use refrigerant, I cannot use the refrigerants because the codes will not let me use the refrigerants in my equipment.’ So, there is that part of the work that needs to be done.” In addition, standards from the likes of the International Electrical Commission also need to be amended to accommodate the different flammable classifications. “To use the highly flammable refrigerant, like propane, you have to limit the charge to less than 150 grams per refrigerant circuit,” he explains.
Brian Rodgers Brian Rodgers, UL principal engineer HVAC says, “If the equipment can meet the requirements of our safety standards, as well the installation requirements that are going into the ASHRAE and building code standards, I think the issues can be mitigated and (flammable refrigerants) can be used safely.” The air conditioning industry is leaning towards the A2L-type refrigerants with a low burning velocity, he explains.
With HCFCs, CFCs and HFCs phased out, the industry started to revisit some of the early refrigerants —carbon dioxide (CO2) plus butane, propane and propylene which are either flammable or operate under very high pressure. Most air conditioning and refrigeration components were designed to carry 400 to 600 pounds per square inch (psi) of pressure. “CO2 runs at 2,500 pounds head pressure in air conditioning,” explained Rodgers.
New Refrigeration Standards for HVACR Industry
The update to ASHRAE Standards is the first step to introduce the next generation of refrigerants, like HFOs, which would reduce greenhouse gas emissions of air-conditioning and refrigeration systems.The standards include an update to the flammability categories for A2L, that are lower flammability refrigerants and can be used in homes for human comfort once the standard is adopted by the International Code Council (ICC). The ICC is the association dedicated to developing model codes and standards used in the design, build and compliance process to construct safe, sustainable, affordable and resilient structures.
Global fire safety common principles
Underwriters Laboratories recently participated in the International Fire Safety Standards (IFSS) Coalition, comprising over 80 fire safety leadership organizations. The coalition’s objective is safety and management of buildings to save more lives by reducing risks and preventing fires. The launch of International Fire Safety Standard Common Principles (IFSS-CP) follows extensive works around the regulation and control of fire safety measures. The IFSS Coalition presented the document to the United Nations in Geneva on October 7, 2020. The Committee welcomed the IFSS Common Principles: Safe Buildings Save Lives to be published as an UN ECE standard and to apply the Common Principles to promote the safety of buildings.
Regulations reducing HFC
New regulation targets super-pollutant HFCs in cooling. Updating existing standards and codes, which currently prevent market uptake of HFC-free alternatives, is critical to implementation of a global phase down of HFCs. Christina Starr, Senior Climate Policy Analyst with EIA, also a member of the US standards technical panel for air conditioners, UL 60335-2-40 said, “Climate-friendly hydrocarbon refrigerants have been safely used in billions of household refrigerators around the world for decades, but have been largely blocked in air conditioning by outdated standards.” It is incredibly important for countries to support this proposal to unlock the full climate benefits of reducing HFCs and increasing energy efficiency in cooling.
California Air Resources Board (CARB) recently approved a new regulation to reduce emissions of super pollutant HFC refrigerants across many sectors using cooling equipment, including supermarkets and air conditioners. The regulation is the first in the U.S. to enact measures to ban many HFCs in new equipment, requiring manufacturers and end-users to use more climate-friendly alternatives, while also tackling existing emissions and venting of refrigerants. Starting 2022, supermarkets will be allowed to only purchase systems using refrigerants with a GWP less than 150. Supermarkets will also have to meet benchmarks for reducing their refrigerant footprint in existing stores, by more than half in 2030.
Phase-out of HFCs by appliance industry
The research program funded by ASHRAE, the AHRI and U.S. Department of Energy (DOE), “…part of an ongoing global effort to phase down the use of high GWP refrigerants and identify appropriate climate-friendly alternatives.”
In addition, “Association of Home Appliance Manufacturers (AHAM) is seeking the support of government and safety authorities — to voluntarily phase down the use of HFC refrigerants used in household refrigerators and freezers after 2024.” AHAM indicated that the goal enables safety, energy efficiency, component compatibility and other considerations to be adequately addressed. EPA SNAP Rule 21 subsequently set the phase-out to be by January 2, 2021.
Licensing reforms needed to cover flammable refrigerants.
If there is any room for reform, there is a need for a more specific application of flammable laws. There is a complex regulatory burden on the HVACR industry, when it comes to licensing and registration, yet, not one of these laws deals specifically with flammable refrigerants. Speaking at CCN Live 2020, Weir Legal & Consulting special counsel, Krista Weymouth, said there is a hydrocarbon specific license registration scheme that applies in Queensland as well as occupation specific licenses and dangerous goods permits but nothing for flammable refrigerants. “There is the ARC license of course but none of these have a focus on flammables,” she said. It raises the question: Is a flammable license required to ensure technicians using refrigerants have the right competencies!
This industry needs to give serious consideration to a licensing regime that covers flammables. It covers laws and regulations created to provide industry with a navigational tool to help make the transition to low GWP refrigerants.
Global greenhouse gas emissions
COVID-19 pandemic has presented a massive new global health crisis, on top of the ongoing global climate crisis. The significant but temporary emission reductions that have resulted from the COVID-19 lockdown will unfortunately not be enough. The cooling is an essential service, not only for comfort but also to cool our food and vaccines etc., for extended periods. Ironical to say, but refrigerants that used to cool, continue to be the same refrigerants, contributing to global climate crisis. We have little time left to waste! Global greenhouse gas emissions need to drop by half by 2030 and reach net-zero by mid-century to avoid the worst climate impacts. Cooling has to be a key part of any net-zero targets. We must agree that 2021 must be utilized to address HFC refrigerant cause and support meeting net-zero building emissions.
Do we know that to stop global warming temperature rise, a trillion tons of carbon dioxide need to be removed from the air. HFC was introduced as a replacement for ozone-depleting CFCs and HCFCs. The new standard is important for the future of HVACR, as the industry begins to move to the new refrigerants for better safety standards and procedures. From fire point of view of burning velocity, A2L compounds are less ready to Ignite as they have low burning velocity as compared to propane, which is a very good refrigerant with relatively low GWP chemical makeup.
Conclusively, it was discovered through research that the refrigerant ignited within 12 seconds, during experiments conducted by UL. The requirements in UL 60335-2-40 will have mitigation methods for preventing leaks and ignition of the refrigerant in the event of a leak. We must ensure that HVACR industry leads the global response to green recovery and the market includes the use of equipment incorporated with the latest technology in the existing HVAC unit to make it more energy efficient sticking to new standards. Legislative changes and import restriction will mean the industry is moving towards low GWP refrigerants.
The year 2020 that brought unwarned global challenge, taught us varied lessons. The cooling industry needs to employ all the tools to bring clean, efficient and sustainable technologies, researching new set of refrigerants, faster to the market. As the demand for cooling rises, end-users, both commercial and residential seek better standards and low flammable refrigerants, better efficiency and better environment, in the long term.
By Gopal Krishna Anand