The Reason Why Ventilation Duct Hose Pipe is Sucked Flat in Use

Why are high temperature resistant duct hose pipe, nylon fabric duct hose pipe and similar duct hose pipe sucked flat when ventilated or aspirated? I believe a lot of customers want to know, and lots of people have encountered this situation. So, why are ventilation duct hose pipes sucked flat? In fact, the main problem…