1 The whole system is air-proof.

2 Good air-proof performance. The electrical parts inside the shell can be used safely.

3 The characteristic, equipment and technology of preparing zinc powder using air-proof submerged arc furnace are discussed, on the other hand, the plant practice is also introduced.

4 Adoption of top - quality insulating materials and highly air-proof design can avoid unnecessary loss of energy.

5 It is proved by the experiments that the quality of air-proof of the device is very important for realizing the non-oxidation healing.

6 With card-board, oil-cloth and canvas, she made the lattice-work air-proof and light-proof.