Check also known as flue fire valve, this product is a new national patented product developed by China's Ministry of Construction to promote environmentally friendly products, in modern housing construction would be a wide range of applications, flue valve generation, to a new high-end residential solve a big problem, it not only to prevent the fumes from the back but also play the role of pipeline connections for high-rise exhaust ventilation system, this type of design for public and residential high-rise flue kitchen, toilet and some other use, both to ensure the smooth flow of exhaust, but also effectively prevent fume flow backward.