近年来，氢氟碳化合物（HFC）制冷剂的零臭氧消耗潜能（ODP）一直是其在供暖、通风、空调和制冷（HVAC&R）产品中广泛采用的主要驱动力。然而，许多氢氟碳化合物具有相对较高的全球变暖潜能（GWP），这促使工业界对低GWP替代制冷剂进行评估。目前广泛使用的几乎所有制冷剂都是不可燃的，按ANSI/ASHRAE标准34分类为A1，但许多可行的低浓度制冷剂- GWP制冷剂，包括某些HFC和氢氟烃（HFO），是易燃的。ANSI/ASHRAE标准34-2013包括一个新的可燃性分类A2L，专门用于低燃烧速度的无毒制冷剂。与A2和A3制冷剂相比，A2L制冷剂的危险性较低。A3碳氢化合物（HC）制冷剂，如丙烷（R-290）和异丁烷（R-600a），由于其ODP为零且GWP较低，也被引入一些应用中。 制定安全规范和标准以减轻易燃性风险对于确保消费者、服务技术人员和建筑物居住者的安全至关重要。该项目的目标是:在不同的最终用途和建筑行业中，描述安全使用易燃制冷剂的当前国际和国内最佳实践。描述美国目前的做法和易燃制冷剂使用标准中的潜在差距。利用这项研究，为美国的易燃制冷剂推荐指南。 建议进行适当的测试，以验证这些指南。引文:ASHRAE研究

The zero ozone-depleting potential (ODP) of hydrofluorocarbon (HFC) refrigerants has been the major driver for their widespread adoption in heating, ventilation, air conditioning and refrigeration (HVAC&R) products in recent years. However, many HFCs have relatively high global warming potential (GWP), which has driven industry to evaluate low-GWP alternative refrigerants. Nearly all refrigerants currently in widespread use are nonflammable, classified A1 by ANSI/ASHRAE Standard 34, but many viable low-GWP refrigerants, including certain HFCs and hydrofluoroolefins (HFO), are flammable. ANSI/ASHRAE Standard 34-2013 includes a new flammability classification, A2L, specifically for non-toxic refrigerants with low burning velocity. A2L refrigerants have less dangerous flammability characteristics than A2 and A3 refrigerants. A3 hydrocarbon (HC) refrigerants, such as propane (R-290) and isobutane (R-600a), are also being introduced in some applications due to their zero ODP and low GWP. Development of safety codes and standards to mitigate flammability risks is essential to ensuring safety of consumers, service technicians, and building occupants.The objectives of this project were to:Characterize current international and domestic best practices for safe use of flammable refrigerants across various end-uses and building sectors.Characterize current US practices and potential gaps in standards for the use of flammable refrigerants.Leverage this research to recommend guidelines for flammable refrigerants in the U.S.Recommend appropriate testing to validate these guidelines.