Types of cut-off doors How many kinds of cut-off gate valves are there?

According to the different opening and closing functions of valves, there are many classification methods of valves, and the following are introduced here. 1. Classification by function and use (1) Block valve: Block valve, also known as closed-circuit valve, is used to connect or cut off the medium in the pipeline. Block valves include gate valves, globe valves, plug valves, ball valves, butterfly valves and diaphragms. (2) Check valve: Check valve, also known as check valve or check valve, is used to prevent the medium in the pipeline from flowing backwards. The bottom valve of water pump suction switch also belongs to the category of check valve. (3) Safety valve: The function of the safety valve is to prevent the medium pressure in the pipeline or device from exceeding the specified value, so as to achieve the purpose of safety protection. (4) Control valve: Control valve includes control valve, throttle valve and pressure reducing valve, and its function is to adjust parameters such as pressure and flow rate of medium. (5) Diverter valve: Diverter valve includes various distribution valves and traps. Used to distribute, separate or mix the media in the pipeline. 2. Vacuum valves classified by nominal pressure (1): refer to valves with working pressure lower than standard atmospheric pressure. (2) low-pressure valve: refers to the valve with nominal pressure PN ≤ 1.6Mpa; (3) medium-pressure valve: refers to the valve with nominal pressure PN of 2.5, 4.0 and 6.4Mpa; (4) high-pressure valve: refers to the valve with nominal pressure PN of 10 ~ 80 MPa. (5) Ultra-high pressure valve: refers to the valve with nominal pressure PN≥ 100Mpa. 3. According to the working temperature classification (1), ultra-low temperature valves are used for valves with medium working temperature of t450℃. 4. According to the classification of driving mode (1), automatic valve refers to the valve that does not need external driving, but relies on the energy of the medium itself to make the valve act. Such as safety valves, pressure reducing valves, steam traps, check valves, automatic control valves, etc. (2) Electric valve: Electric valve can be driven by various power sources. Electric valve: A valve driven by electricity. Pneumatic valve: A valve driven by compressed air. Hydraulic valve: A valve driven by the pressure of a liquid, such as oil. In addition, there are combinations of the above driving modes, such as pneumatic-electric valves. (3) Manual valve: Manual valve is operated manually with the help of handwheel, handle, lever and sprocket. When the opening and closing torque of the valve is large, the wheel or worm gear reducer can be installed between the handwheel and the valve stem. Universal joints and transmission shafts can also be used for remote operation if necessary. 5.( 1) Small-caliber valves are classified by nominal diameter: valves with nominal diameter DN≤40mm. (2) Intermediate diameter valve: a valve with a nominal diameter DN of 50 ~ 300mm. (3) Large-diameter valves: valves with a nominal diameter of 350 ~ 1200mm. (4) Extra-large-diameter valves: valves with a nominal diameter of DN ≥1400 mm. 6.( 1) Globe valves are classified according to their structural characteristics: the opening and closing parts (disc) are driven by the valve stem to move up and down along the center line of the valve seat; (2) Plug valve: the opening and closing part (gate valve) is driven by the valve stem and moves up and down along the center line perpendicular to the valve seat; (3) Plug valve: the opening and closing part (cone plug or ball) rotates around its own center line; (4) Swing valve: the opening and closing part (disc) rotates around the shaft outside the valve seat; (5) Butterfly valve: the opening and closing part (disc) rotates around the fixed shaft in the valve seat; (6) Slide valve: The opening and closing parts slide in the direction perpendicular to the channel. 7. According to the connection mode, it is classified as (1) threaded connection valve: the valve body has internal thread or external thread and is connected with the pipeline through thread. (2) Flange valve: The valve body is connected by flange and connected with the pipeline flange. (3) Welding connecting valve: The valve body has a welding groove and is welded with the pipeline. (4) Clamp connection valve: The valve body has a clamp and is connected with the pipe clamp. (5) Socket-type connecting valve: connected to the pipeline through a ferrule. (6) Clamping valve: a connection form that directly clamps the valve and two pipelines together with bolts. 8. According to the classification of valve body materials (1), metal valves: the valve body and other parts are made of metal materials. Such as cast iron valves, carbon steel valves, alloy steel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, etc. (2) Non-metallic valve: Its valve body and other parts are made of non-metallic materials. Such as plastic valves, ceramic valves, enamel valves, FRP valves, etc. (3) Metal-lined valve body: The valve body is made of metal, and all the main surfaces in contact with the medium are lined, such as rubber-lined valves, plastic-lined valves and ceramic-lined valves.