Shield knife gate valve: this valve is suitable in wicked condition, whose shield is appended on the body to keep away the gates corrupting from outside condition, so as to swell the use-life of the gate. The advantages of this valve are, flexible open-down, light-small structure, excellence sealing and what is more, the rubber seat ring can be changed easily, those specialties make swell the use-life of the valve, also economize the waste of resource..