According to the role of the opening and closing valve, there are many classification methods for valves. The following are introduced here.
1. Classified by purpose and use
(1) Shut-off valve: A shut-off valve, also known as a closed-circuit valve, is used to switch on or off the medium in the pipeline. Cut-off 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 backflow of media in the pipeline. The bottom valve of the water pump suction is also a check valve.
(3) Safety valve: The function of the safety valve is to prevent the pressure of the medium in the pipeline or device from exceeding the specified value, so as to achieve the purpose of safety protection.
(4) Regulating valve: The regulating valve includes a regulating valve, a throttle valve and a pressure reducing valve, and its function is to adjust the pressure, flow rate and the like of the medium.
(5) Diverter valve: The diverter valve type includes various distribution valves and traps, etc., which function to distribute, separate or mix the medium in the pipeline.
2. Classified by nominal pressure
(1) Vacuum valve: refers to a valve whose working pressure is lower than the 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, 6.4Mpa.
(4) High pressure valve: refers to the valve whose working pressure PN is 10~80Mpa.
(5) Ultra high pressure valve: refers to the valve with nominal pressure PN≥100Mpa.
3. Classified by working temperature
(1) Ultra-low temperature valve: for valves with media operating temperature t < -100 °C.
(2) Cryogenic valve: for valves with medium working temperature -100 °C ≤ t ≤ -40 °C.
(3) Normal temperature valve: used for valves with medium working temperature -40 °C ≤ t ≤ 120 °C.
(4) Medium temperature valve: for medium working temperature 120 ° C
(5) High temperature valve: for valves with medium working temperature t>450°C.
4. Classified by driving method
(1) An automatic valve is a valve that does not require external force to drive, but relies on the energy of the medium itself to actuate the valve. Such as safety valves, pressure reducing valves, traps, check valves, automatic regulating valves, etc.
(2) Power-driven valves: Power-driven valves can be driven by various power sources.
Electric valve: With an electric drive valve.
Pneumatic valve: A valve driven by compressed air.
Hydraulic valve: A valve that is driven by a liquid pressure such as oil.
In addition, there are combinations of the above several driving methods, such as gas-electric valves.
(3) Manual valve: The manual valve uses manpower to manipulate the valve action by means of the hand wheel, handle, lever and sprocket. When the valve opening and closing torque is large, the wheel or worm gear reducer can be arranged between the hand wheel and the valve stem. If necessary, you can also use the universal joint and the drive shaft for remote operation.
In summary, the valve classification method is many, but mainly classified according to its role in the pipeline. General purpose valves in industrial and civil engineering can be divided into 11 categories, namely gate valves, globe valves, plug valves, ball valves, butterfly valves, diaphragm valves, check valves, throttle valves, safety valves, pressure reducing valves and steam traps. Other special valves, such as valves for instruments, valves for hydraulic control piping systems, valves for various chemical machinery and equipment, etc., are not included in the scope of this book.
5. Classified by nominal diameter
(1) Small-diameter valve: a valve with a nominal diameter of DN ≤ 40mm.
(2) Medium diameter valve: a valve with a nominal diameter DN of 50 to 300 mm.
(3) Large-diameter valve: The valve with nominal valve DN is 350-1200mm.
(4) Extra large diameter valve: valve with nominal diameter DN ≥ 1400mm.
6. Classification by structural characteristics
(1) sectional shape: the opening and closing member (valve) is driven by the valve stem to move up and down along the center line of the valve seat;
(2) cock shape: the opening and closing member (gate valve) is driven by the valve stem to move up and down along the center line perpendicular to the valve seat;
(3) Plug valve: the opening and closing member (cone plug or ball) rotates around its own center line;
(4) Swing valve: the opening and closing member (valve) rotates around the shaft outside the seat;
(5) Butterfly line: the opening and closing member (disc) rotates around a fixed shaft in the valve seat;
(6) Spool line: The opening and closing member slides in the direction perpendicular to the passage.
7. Sort by connection method
(1) Threaded connection valve: The valve body has internal or external thread and is threadedly connected to the pipe.
(2) Flange connection valve: The valve body is flanged and connected to the pipe flange.
(3) Welded connection valve: The valve body has a welding groove and is welded to the pipe.
(4) Clamp connection valve: The valve body has a clamping mouth and is connected with the pipe clamp.
(5) ferrule connection valve: connected with the pipe with a ferrule.
(6) Matching the connecting valve: a connection form in which the valve and the two pipes are directly clamped together by bolts.
8. Classified by body material
(1) Metal material valve: The valve body and other parts are made of metal material. 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.
(2) Non-metallic material valves: parts such as valve bodies are made of non-metallic materials. Such as plastic valves, ceramic valves, 搪 valves, glass steel valves, etc.
(3) Metal valve body lining valve: The shape of the valve body is metal, and the main surfaces in contact with the medium are lining, such as rubber-lined valve, plastic-lined valve, and ceramic-lined valve.