鉴于科技的进步和实验经验,ISO/TC 209出台I SO14644-1:2015《按粒子浓度划出空气洁净度等级》Classification of air cleanliness by particle concentration 比 ISO14644-1:1999《空气洁净度等级》Classification of air cleanliness技术概念更清晰,使用更方便;实事求是,更赋灵活性:分级表中,所有浓度值都是累积,包括所有大于等于关注粒径(Considered particle size)的粒子的最大允许浓度值(Maximun allowable concentration siae),浓度限值.区域粒子浓度太高,浓度限值不适用;或者由于低浓度时采样和统计方法的局限性区域分级不适用.按统计学技术概念,决定检测洁净度最少采样点数NL;NL值与洁净度无直接关联.作为标准应用的补充,超净环境检测需关注超高过滤器滤材最易穿透粒径MPPS,Most penetrating particle size.
Discussion on classification standard of cleanliness of cleanroom
Based on progress and experimental experiences,ISO 14644-1:2015 Classification of air cleanliness by particle concentration,compared with its old version ISO 14644-1:2019 Classification of air cleanliness,is clearer in technical concepts,more convenient in application,and seeking truth from facts with flexibility.In classification table,all concentration values are accumulative,including maximum allowable concentration or concentration limits of all particles equal or larger than considered particle sizes.The limits are not applicable when local concentration is too high;or,local classification is not applicable due to limits of sampling and statistical method when concentration is low.According to statistical concept,minimum sampling points NL are determined for cleanliness test.NL has no relation wit cleanliness.As supplement to application of above standard,MPPS should be considered for ULPA paper in ultra-clean environment test.
Particle Considered particle size Occupation state As built At rest Operational Concentration limit MPPS Confidence level
万方数据
维普
