通过对蒸气压缩式制冷系统现场检漏的观测,发现保压试验满足国家标准GB50274-98《制冷设备、空气分离设备安装工程施工及验收规范》的合格判据时,发泡试验还有检出漏孔的可能.针对这一现象,对发泡和保压试验的不同作用,以及“GB50274-98”关于保压试验的漏率判据进行分析.结果表明,“GB50274-98”关于测定压力降不大于试验压力值的1％为合格的相对漏率判据对系统整体泄漏的限制要求偏低,也不能有效控制大容积被测系统粗漏漏孔的出现几率.进一步研究指出,通过保压试验可以直接评价系统整体漏率和对制冷系统运行中的制冷剂非事故耗损进行评估.同时提出现场保压试验应提高压力表精度和延长保压时间,以获得更准确的试验数据.研究可为提高制冷系统现场检漏质量和改进评定方法提供参考.%The observation of leak detection on site for vapor compression refrigeration system showed that foamy leaks might be found by foamy test, even when maintaining pressure test met the requirement of national standard GB50274-98 "code for construction and acceptance of refrigeration and air separation equipment installation engineering". To address this issue, different effects of foam and maintaining pressure test, as well as leakage rate criterion for maintaining pressure test in GB50274-98 were studied. It is shown that the relative leakage rate criterion in GB50274-98, I.e, pressure drop should not exceed 1% of tested pressure, was not rigorous enough for global leakage limitation and failed to have a valid control over the large leaks in the large tested systems. Further investigation pointed out that maintaining pressure test can directly evaluate global leakage rate and non-accident leakage of refrigerants. To obtain more accurate data in the test, accuracy of manometers used on site should be improved and maintaining pressure period should be extended. This study provides a useful strategy for improving quality of on-site leak detection and optimizing methods of evaluation for refrigeration system.
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