The type of collecting cover of secondary gas cleaning and dust-removing device is introduced, the difference between the traditional ones and this illustrated, the shortcomings of those pointed out, the reasonableness of top absorbing cover analyzed, the feasibility of this process proved by the live-testing data.

In consideration of the limited space of tondish dump-station, this paper proposes four kinds of design programs: lateral air-breathing cover, breath-blow cover, moving two-stage upper cover, divided closed-cover.

Objective To explore the effect of applying improved mask for oxygen-inhalation in tracheoscopy in the sputum clearance and occupational prevention.