Lead or annealed copper washers are most often used in fluorine and other reactive fluoride service.
铅或退火铜垫圈最经常用于氟和其它活泼氟化物设施。
2
Inorganic mineral elements in tea are about 27 species, including phosphorus, potassium, sulfur, magnesium, manganese, fluoride, aluminum, calcium, sodium, iron, copper, zinc, selenium and other.
茶叶中的无机矿质元素约有27种，包括磷、钾、硫、镁、锰、氟、铝、钙、钠、铁、铜、锌、硒等多种。
3
Conceal disturbing elements like iron, copper, lead with hydrogen fluoride amine-EDTA, add the potassium iodide to separate iodine, and take starch as indicator, titrate with sodium hyposulfite.