Classification and selection of water supply and drainage valves:
Water supply and drainage valves are often used in domestic water supply, fire protection systems and industrial water supply systems. Used to control flow, water level, etc. Common products are: 100X remote control float valve, 200X pressure reducing valve, 300X slow closing check valve, 400X flow control valve, 500X pressure relief valve, etc. And a variety of pressure reducing valves, check valves, etc. for different purposes.
Water supply and drainage valve classification
According to the different functions of opening and closing valves, there are many classification methods of valves. Here are the following.
1. Classification by function and purpose
(1) Cut-off valve: The cut-off valve is also called a closed-circuit valve, whose function is to connect or cut off the medium in the pipeline. Block valves include gate valves, globe valves, plug valves, ball valves, butterfly valves and diaphragm valves.
(2) Check valve: Check valve is also called one-way valve or check valve, its function is to prevent the medium in the pipeline from flowing back. The bottom valve on the suction side of the pump also belongs to the non-return valve category.
(3) Safety valve: The function of 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 valves: Regulating valves include regulating valves, throttle valves and pressure reducing valves, whose function is to regulate the pressure, flow and other parameters of the medium.
(5) Diversion valve: Diversion valves include various distribution valves and traps, etc., whose function is 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 a 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 a valve with a nominal pressure PN≥100Mpa.
3. Classified by working temperature
(1) Ultra-low temperature valve: used for medium working temperature t
(2) Cryogenic valve: a valve used for medium working temperature －100℃≤t≤－40℃.
(3) Normal temperature valve: used for valves with medium working temperature -40℃≤t≤120℃.
(4) Medium temperature valve: used for medium working temperature 120℃
(5) High temperature valve: used for valves with medium working temperature t>450℃.
4. Classified by driving mode
(1) An automatic valve refers to a valve that does not require external drive, but relies on the energy of the medium to make the valve actuate. Such as safety valves, pressure reducing valves, traps, check valves, automatic control valves, etc.
(2) Power-driven valves: Power-driven valves 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 liquids such as oil.
In addition, there are combinations of the above several driving methods, such as pneumatic-electric valves.
(3) Manual valve: Manual valve uses hand wheel, handle, lever, sprocket, and manpower to manipulate the valve action. When the valve opening and closing torque is large, this wheel or worm gear reducer can be set between the handwheel and the valve stem. If necessary, the universal joint and drive shaft can also be used for long-distance operation.
In summary, there are many ways to classify valves, but they are mainly classified according to their role in the pipeline. General 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 traps. Other special valves, such as valves for instruments, valves for hydraulic control piping systems, and valves for various chemical machinery and equipment bodies, are not within the scope of this book.
5. Classification by nominal diameter
(1) Small diameter valve: Valve with nominal diameter DN≤40mm.
(2) Middle diameter valve: the valve whose nominal diameter DN is 50～300mm.
(3) Large-diameter valves: valves whose nominal valve DN is 350～1200mm.
(4) Extra large diameter valve: Valve with nominal diameter DN≥1400mm.
6. Classification by structural characteristics
(1) Sectional door shape: the opening and closing parts (valve clack) are 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 part (gate valve) is driven by the valve stem to move vertically along the center line of the valve seat;
(3) Plug valve: the opening and closing part (cone plug or ball) rotates around its own centerline;
(4) Swing valve: the opening and closing part (valve) rotates around the axis outside the seat;
(5) Butterfly line: the opening and closing part (disc) rotates around the fixed axis in the valve seat;
(6) Slide valve line: The opening and closing piece slides in the direction perpendicular to the channel.
7. Classified by connection method
(1) Threaded connection valve: The valve body has an internal thread or an external thread, which is connected with the pipe thread.
(2) Flange connection valve: The valve body has a flange, which is connected with the pipeline flange.
(3) Welding connection valve: The valve body has a welding groove, which is welded to the pipeline.
(4) Clamp connection valve: The valve body has a clamp, which is connected with the pipe clamp.
(5) Ferrule connection valve: the ferrule is connected to the pipeline.
(6) Wafer connection valve: a connection form in which the valve and the two pipes are directly clamped together with bolts.
8. Classified by valve body material
(1) Metal material valve: its valve body and other parts are made of metal material. Such as cast iron valve, carbon steel valve, alloy steel valve, copper alloy valve, aluminum alloy valve, lead alloy valve, titanium alloy valve, Monel alloy valve, etc.
(2) Non-metallic material valve: its valve body and other parts are made of non-metallic material. Such as plastic valve, ceramic valve, enamel valve, glass fiber reinforced plastic valve, etc.
(3) Metal valve body lining valve: 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.
9. Valve model arrangement
The valve model should usually indicate the valve type, drive mode, connection form, structural characteristics, sealing surface material, valve body material, and nominal pressure. The standardization of valve models facilitates the design, selection and sales of valves. Nowadays, there are more and more types and materials of valves, and the design of valve models is becoming more and more complicated. Although my country has a unified standard for valve model compilation, it is increasingly unable to meet the needs of the development of the valve industry. At present, valve manufacturers generally adopt a unified numbering method; where a unified numbering method cannot be used, each manufacturer formulates a numbering method according to its own needs.
“The Method of Compiling Valve Models” is applicable to gate valves, throttle valves, ball valves, butterfly valves, diaphragm valves, plunger valves, plug valves, check valves, safety valves, pressure reducing valves, and steam traps for industrial pipelines. It includes the model of the valve and the naming of the valve.