free from contamination

基本解释

The unique advantages are: no contamination, high efficiency, free from power, less weight, easy for cleaning and maintenance and wide range of application.
具有：无脱落污染、效率高、不需电能消耗、重量轻、容易清洗、便于维修、应用范围广泛等特点。
andynt.china.mainone.com
The invention relates to many articles, particularly those public use materials for easy contamination, free from scribbling, without prevention of the sticky paper.
现有的很多物体，尤其是公共使用的物体，表面易粘污、不防涂画、不防粘贴纸张。
ip.com
The presence of exogenous surface contamination, including dirt, grease, free iron from contact with steel tooling, and so forth, may interfere with the formation of the passive film.
外生的表面污染，包括：尘土、油脂、来自钢铁加工的游离铁等等，可以影响到钝化膜的生成。
blog.sina.com.cn