面对更严格的监管压力，对环境可持续物质的需求很高。进入市场的低全球变暖（GWP）制冷剂数量正在迅速增加，以满足市场需求。根据ISO 817和ANSI/ASHRAE标准34（ASHRAE 2008、ISO 2014）的分类，许多新型低GWP制冷剂为“轻度易燃”或“2L”。新的制冷剂可燃性等级为供暖/空调/制冷行业提供了潜在的选择，以满足环境法规的要求，设备设计为低可燃性。轻度易燃制冷剂是指燃烧速度（BV）小于10厘米/秒（3.94英寸/秒），燃烧热（HOC）小于19000千焦/千克（44194英热/磅）的制冷剂。虽然不属于分类要求的一部分，但轻度易燃制冷剂具有较高的较低可燃性水平（LFL）和较高的最低点火能量（MIE）。 目前，2L制冷剂的MIE测试采用了ASTM E582，它使用电火花点火源（ASTM E582-13）。该试验的结果表明，通常情况下，2L类制冷剂的MIE值比高度易燃或ISO 817/ANSI 34 3类制冷剂大两到四个数量级。轻度易燃制冷剂的高MIE值表明，它们通常很难点燃。一个相对未被探索的潜在点火源是一个热表面，可以在空调辅助加热器和其他制冷系统中找到。几个设备标准中也规定了最高热表面温度。最近，对释放到热表面的几种2L制冷剂的潜在着火/不着火进行了审查。设计了一个新的测试，模拟一台设备内的热表面上2L制冷剂泄漏。 特别是，将单个制冷剂释放到加热的金属表面上，并在释放制冷剂后的设定时间段内观察到潜在的点火情况。有趣的是，记录的点火值比文献中的自动点火温度（AIT）值高几百度。这项工作总结了所使用的测试设备、使用各种2L制冷剂进行的热表面点火测试以及点火测试结果。引用:2016年年度会议，密苏里州圣路易斯，会议论文

Faced with more stringent regulatory pressures, the demand for environmentally sustainable substances is high. The number of low global warming (GWP) refrigerants entering the market is rapidly increasing to meet market needs. Many of the new low GWP refrigerants are "mildly flammable" or "2L" as classified by ISO 817 and ANSI/ASHRAE Standard 34(ASHRAE 2008, ISO 2014). The new refrigerant flammability class provides the heating/air-conditioning/refrigeration industry potential options to meet environmental regulations with equipment designed for low flammability. Mildly flammable refrigerants are defined as refrigerants which have burning velocity (BV) less than 10 cm/sec (3.94 in/sec) and heat of combustion (HOC) less than 19,000 kJ/kg (44,194 Btu/lb). Although not part of classification requirements, mildly flammable refrigerants have higher lower flammability level (LFL) and exhibit higher minimum ignition energy (MIE). Current MIE testing of 2L refrigerants has employed ASTM E582, which use an electrical spark ignition source (ASTM E582-13). Results from that testing has shown that typically, class 2L refrigerants have MIE values which are two to four orders of magnitude greater than highly flammable or ISO 817/ANSI 34 class 3 refrigerants. The high MIE values determined for mildly flammable refrigerants denotes that they are typically very difficult to ignite.A relatively unexplored potential ignition source is a hot surface which can be found in air conditioning auxiliary heaters and other refrigeration systems. Maximum hot surface temperatures are also specified in several equipment standards. Recently, work was conducted to review potential ignition/non-ignition for several 2L refrigerants which were released onto a hot surface. A new test was designed to simulate a 2L refrigerant leak onto a hot surface within a piece of equipment. In particular, individual refrigerants were released onto a heated metal surface and potential ignition was observed for a set time period after the refrigerant was released. Interestingly, ignition values noted were several hundred degrees higher than literature auto-ignition temperature (AIT) values. This work summarizes the test apparatus used, the hot surface ignition testing conducted with various 2L refrigerants, and ignition testing results.