The tube contains inert materials impregnated with o-tolidine, which leads to coloring reaction when in contact with nitrogen dioxide diffusing into to the tube.

• 主要结合气体分子扩散原理和化学吸收原理,在检气管内装有浸渍过显色剂的载体,检气管处于有二氧化氮气体的环境中,在一定时间内,两端载体发生一定长度的显色反应。