How big a pipe should be used for AS pre-embedding in civil air defense in the electrician’s basement?

The AS embedded pipe in the civil air defense in the electrician's basement is connected to a manual or hand-electric dual-purpose sealing valve with a nominal diameter of DN400. The actual inner diameter of the pipe is 441.

Civil air defense ventilation method signal box AS box ventilation The mode signal box (signal light box) and the ventilation mode signal control box produced by our company form a three-proof control system. Special products dedicated to civil air defense command projects, underground hidden facilities and tunnels, military and paramilitary projects and basements of ordinary air defense projects.

It is mainly used to display and alarm the air quality status inside the engineering bunker, and to reflect the electronic alarm signal from the control cabinet. It has two alarm modes, sound and light alarm, and has good display performance and visual effects.