1.The structure of the threshold must effectively prevent the spread of fire.

2.For the threshold with smoke prevention performance, a smoke prevention device must be provided to effectively prevent the smoke from overflowing. All materials of the smoke prevention device should be non-combustible materials.

3.The smokeproof device of the door sill is in uniform contact with the sealing surface of the sill and the surface of the roller blind. The contact surface shall not be less than 80% of the width of the door opening, and the gap of the non-contact surface shall not be greater than 2 mm.

4.The installation of the door sill should be firm and the distance between the pre-buried steel parts should not exceed 600mm.

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