A butterfly valve advantages:? Short opening and closing times. ? Operating torque small installation space and light weight, low cost small fluid resistance two disadvantages:???? Is not a one-way sealed high pressure high temperature intolerance, and easy to leak Third, the difference between soft and hard seal of a seal,?? Hard Seal: Sealing both sides of metal materials, high temperature, wear out, good mechanical properties. Long life, but relatively soft seal sealing performance is poor (eg steel + steel; steel + copper; steel + graphite; steel + alloy). 2, soft seal: the side seals on both sides of the metal material deputy, the other side is a flexible non-metallic materials, easy to aging, wear, life is short, but better sealing performance (steel + rubber; steel + poly four fluoride) Fourth, the difference between the midline structures and an eccentric structure, midline structures: that the valve shaft sealing surface, the valve focus on a center line, this class is mainly used in rubber soft sealing butterfly valve, simple structure, good sealing performance, rubber have some wear and elastic compensation, but the moment when you open and close large, medium temperature usually does not exceed 80 degrees. Condition: used hoist water, sewage and other pipeline, the general use of cast iron, lined with rubber, affordable, desired effect, can be equipped with other related effort or automatic drive. Two, three eccentric structure: both the stem axis deviation in the disc center, also deviated from the center of the body, while the valve seat and valve centerline of the centerline and then forming a deviation angle, making the butterfly valve in the opening and closing process, the disc's sealing surface in the opening moments from the seat sealing surface immediately, but will be in close contact with an instant and pressed seat sealing surface. The cam effect, completely eliminating the friction between the valve seat and seal at 90 degrees during the trip, to solve the valve due to wear and tear caused by leakage problems. Make more effort to open, no wear and longer life, better sealing performance. V. General ventilation valve butterfly valve using the same material as the processing and seals, their body temperature with suitable selection may be, nominal ≤0.6MPA, generally applicable to the industry, metallurgy, environmental protection, ventilation pipes for adjusting the flow of the medium . Features:? Media gas, dust and gas, flue gas and other light weight, open and close rapidly operating torque, easy to operate, energy smart?