China Galvanized Gabion,Galvanized Gabion Mesh supplier & manufacturer, offer low price, high quality Galvanized Gabion 4X4,Galvanized Gabion Boxes, etc.
Galvanized Gabion boxes and mattresses are widely used for river and slope protection, the triple twist hexagonal woven mesh fabric containers offering the simple, efficient, environment friendly and cost effective gabion work solution filled with natural stone.
Galvanized Gabion,Galvanized Gabion Mesh,Galvanized Gabion 4X4,Galvanized Gabion Boxes ANPING HAOCHANG WIRE MESH MANUFACTURE CO.,LTD , https://www.hcgabions.com
Water supply and drainage engineering in the selection of knowledge of the valve
First, the valve classification 1, according to the purpose and role of classification <> Shut-off valve is mainly used to cut off or connect the media flow. Including gate valve, globe valve, diaphragm valve, ball valve, plug valve, butterfly valve, plunger valve, ball valve, needle valve and so on. <> Regulating valve is mainly used to regulate the flow of media, pressure and so on. Including the control valve, throttle, pressure reducing valve. <> Check valves are used to prevent backflow of media. Includes various configurations of check valves. <> Diverter valves are used to separate, distribute or mix media. Including a variety of distribution valves and traps and other structures. <> Safety valves are used to protect the medium against overpressure. Including various types of safety valve. 2, according to the main parameters of classification (a) by pressure classification <> vacuum valve working pressure is lower than the standard atmospheric pressure valve. <> Low pressure valve Nominal pressure PN less than 1.6MPa valve. <> Medium pressure valve Nominal pressure PN 2.5 ~ 6.4MPa valve. <> High pressure valve Nominal pressure PN10.0 ~ 80.0MPa valve. <> UHP valve nominal pressure PN greater than 100MPa valve. (B) by the temperature of the medium temperature valve t greater than 450 "C of the valve."> Medium temperature valve 120 "C less than t less than 450" C valve. "> Room temperature -40" C less than t less than 120 "C Valves. <> Cryogenic Valves-100 "C Valves less than t less than -40" C. <> Cryogenic Valves t <-100 "C Valves. (C) by body material classification <> Non-metallic materials valves: such as ceramic valves, glass steel valves, plastic valves. Metal Materials Valves: such as copper alloy valve, aluminum alloy valve, lead alloy valve, titanium alloy valve, Monel alloy valve cast iron valve, carbon steel valve, cast steel valve, low alloy steel valve, high alloy steel valve. <> Metal Body Lined Valves: Lined Lead Valves, Lined Plastic Valves, Lined Enamel Valves. 3, the general taxonomy <> This classification method according to the principle, the role of structural division, is currently the most common international and domestic classification methods. General sub-gate valves, globe valves, throttle valves, instrumentation valves, plunger valves, diaphragm valves, plug valves, ball valves, butterfly valves, check valves, pressure relief valve safety valve, Sewage valve and so on. Second, how to choose the valve The choice of valves, I personally think that rather control the secondary point, the valve must be good, run, run, drip, leak, and fittings and valves are often related. When using the valve: 1, pressure reducing valve, counterbalance valve, etc. must be bypassed; 2, full open full closed with the best ball valve, gate valve; 3, try to use the globe valve; 4, valve resistance calculation should pay attention; , Electric valve must be selected. A, according to the nature of the medium-off valve butterfly valve butterfly valve installed in the pipe diameter direction. In the butterfly valve body cylindrical channel, the disc-shaped disc rotates about the axis, the rotation angle is between 0 ° ~ 90 °, when rotated to 90 °, the valve is fully open state card. Butterfly valve structure is simple, small size, light weight, only a few components. And just turn 90 ° to quickly open and close, easy to operate, while the valve has good fluid control features. When the butterfly valve is fully open, the thickness of the disc is the only resistance to the flow of the medium through the valve body, so the pressure drop across the valve is small and therefore has good flow control characteristics. Butterfly valve seal and metal seal two types of seal. Flexible sealing valves, seals can be embedded in the body or attached to the butterfly plate around. Valves with metal seals generally have a longer life than elastomeric valves, but are harder to seal completely. Metal seals can adapt to higher operating temperatures, while flexible seals have temperature-limited defects. If the butterfly valve is required to be used as a flow control, the main choice is the correct size and type of valve. The structural principle of the butterfly valve is especially suitable for making large diameter valves. Butterfly valve not only in the oil, gas, chemicals, water treatment and other general industry has been widely used, but also used in thermal power station cooling water system. Commonly used butterfly valve clamp butterfly valve and flange two. The butterfly valve on the folder is to use double-headed bolts to connect the valve between the two pipe flanges, flanged butterfly valve is equipped with a flange on the valve, with bolts on both sides of the valve flange connected to the pipe flange. Valve strength performance refers to the ability of the valve to withstand medium pressure. Valves are mechanical products subject to internal pressure and must therefore have sufficient strength and rigidity to ensure long term use without rupture or deformation. Ball valve ball valve is evolved from the plug. It has the same 90 degree rotation action, except that the plug body is a sphere with a circular through hole or passage through its axis. The ratio of the sphere to the channel should be such that when the sphere is rotated 90 degrees, the sphere should be fully spherical at the inlet and outlet to cut off the flow. Ball valve only need to rotate 90 degrees of operation and a small turning moment can be closed tight. The completely equal body cavity provides a medium-sized, straight-through runner with low resistance. Ball valves are generally considered to be the most suitable for direct opening and closing, but recent developments have designed the ball valve to be throttling and controlling flow. The main features of the ball valve is its compact structure, easy operation and maintenance, suitable for general working media such as water, solvents, acids and natural gas, but also for media with bad working conditions such as oxygen, hydrogen peroxide, methane and ethylene. Ball valve body can be a whole, it can be combined. Globe valve stem valve stem valve seat sealing surface perpendicular to. Stem opening or closing stroke is relatively short, and has a very reliable cut off action, making this valve is very suitable as a medium cut off or adjust and throttle. Once the valve flap of the globe valve is open, its contact between the valve seat and the flap sealing surface no longer contacts and has a very reliable cut-off action, making this valve ideal as a medium to cut or adjust Flow use. Once the stop valve is open, its valve seat and disc seal surface no longer have contact between, and therefore its sealing surface mechanical wear and tear less, as most of the valve seat and the disc valve is relatively easy to repair or replacement Sealing components without having to remove the entire valve from the pipeline, which for the valve and pipe welding is integrated into the case is very applicable. The flow direction of the medium as it passes through such a valve changes, so the shut-off valve has a higher flow resistance than the other valves. There are several commonly used stop valves: 1) Angular stop valves; in angle stop valves, the fluid only needs to be changed in one direction so that the pressure drop across this valve is less than that of conventional stop valves. 2) DC shut-off valve; In the DC or Y-type shut-off valve, the valve body flow path and the main flow channel into a slash, so that the flow of state damage than the conventional valve is smaller, so the pressure loss through the valve accordingly Small 3) Plunger globe valve: This type of globe valve is a variation of a conventional globe valve. In this valve, the disc and seat are usually designed based on the plunger principle. Polished valve plunger into a plunger connected with the stem, the seal is set by the plunger in the two elastic ring to achieve. The two elastomeric seals are separated by a collar, and the seal around the plunger is pressed firmly by the load exerted by the bonnet nut on the bonnet. Elastomeric seals are interchangeable and can be made in a wide variety of materials. The valves are mainly used to "open" or "close", but with a special form of plunger or special collar that can also be used to regulate flow . Valve gate valve is used as a cut-off medium, the entire circulation through the fully open, this time the pressure loss of medium operation minimum. Gate valve is usually applied to do not often need to open and close, and keep the gate fully open or fully closed conditions. Not suitable for use as a regulator or throttling. For high-speed flow media, the gate may cause gate vibration when the gate is open partially, and the vibration may damage the sealing surface of the gate and valve seat, which can cause the gate to suffer erosion of the medium. The main difference from the structural form is the form of the sealing element used. According to the form of the sealing element, the gate valve is often divided into several different types, such as wedge gate valve, parallel gate valve, parallel double gate gate valve, wedge double gate gate and the like. The most common forms are wedge gate valves and parallel gate valves. B, by preventing the media back to select the valve The role of this type of valve is to allow only medium to flow in one direction, but also to prevent the flow direction. Usually this kind of valve is automatic working, the valve flap opens under the pressure of the fluid flowing in one direction; when the fluid flows in the opposite direction, the valve flap is acted upon by the fluid pressure and the self-weight of the valve flap to cut off the flow. Which check valve belongs to this type of valve, which includes the swing check valve and lift check valve. Swing check valves have a hinged hinge mechanism and a flap-like flap freely rests against the slanted seat surface. To ensure that the valve flap reaches the proper seating surface every time, the valve flap is designed on the hinge mechanism so that the valve flap has enough swivel-open space for true and complete valve flap contact. The valve flap can be made entirely of metal, or it can be fitted with a leather, rubber or synthetic cover over the metal, depending on the performance requirements. Swing check valve in the fully open condition, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. Lift check valve seat is located on the valve seat sealing surface. In addition to the valve flap valve can be free to rise and fall, the rest of the same as the cut-off valve, the fluid pressure so that the valve flap from the valve seat lifting surface, the media back to cause the valve flap down to the seat, and cut off the flow. Depending on the conditions of use, the valve disc can be of all-metal construction or it can be in the form of a rubber gasket or rubber ring inlaid on the valve disc holder. Like the stop valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than the swing check valve and the flow through the swing check valve is limited Few. C, according to adjust the media parameters Selection of valves in the production process, in order to make the media pressure, flow and other parameters in line with the requirements of the process, the need to install the adjustment mechanism to adjust the above parameters. The main working principle of the adjusting mechanism is to change the valve disc and the flow area between the valve disc and valve seat to achieve the purpose of adjusting the above parameters. Belong to this type of valve collectively referred to as the control valve, which is divided into rely on the media itself driven by self-driven control valves such as pressure relief valves, pressure regulators, etc., where the leading power-driven (such as electricity, compressed air and liquid Power) called his drive control valves, such as electric control valve, pneumatic control valve and hydraulic control valve. D, according to the nature of the valve driven by the use of electricity-driven valves Valves are commonly used drive-driven valves, usually referred to as the drive device for the valve actuator, valve electric device features are as follows: 1) quick opening and closing , Can greatly shorten the time required to open and close the valve; 2) can greatly reduce the labor intensity of the operator, especially for high pressure, large diameter valves; 3) Suitable for installation in the position can not be manually operated or difficult to achieve, easy to implement far 4) facilitate automation of the entire system; 5) Power sources are more readily available than air and liquid sources, and their wiring is easier to lay and maintain than compressed air and hydraulic lines. The disadvantage of valve electric devices is the complex structure, more difficult to use in wet places, when used in explosive media, the need to use explosion-proof measures. Valve actuators driven by the valve type is different, can be divided into two types of Z and Q type. Z-type valve electric device output shaft can turn out a lot of laps, suitable for driving gate valves, globe valves, diaphragm valves; Q-type valve electric device output shaft can only rotate 90. , Suitable for driving plug valves, ball valves and butterfly valves. According to the type of protection are ordinary type, flameproof type (B), heat-resistant type (R) and triple type (that is, outdoor, anti-corrosion, flameproof, Valve electric devices generally by the transmission (gear), motor, stroke control agencies, torque limit agencies, manual - electric switching mechanism, opening indicator and other components. Pneumatic and hydraulic valves Pneumatic valves and hydraulic is a certain pressure of air, water or oil as the power source, the use of the cylinder (or hydraulic cylinder) and piston movement to drive the valve, the general pneumatic pressure of air is less than 0.8MPa, the liquid Dynamic pressure or hydraulic pressure is 2.5MPa ~ 25MPa. Or diaphragm valve; rotary gas and liquid drive device for driving the ball valve, butterfly valve or plug valve. The driving force of hydraulic device is large, suitable for driving large-caliber valves. Such as used to drive the plug valve, ball valve and butterfly valve, the piston must reciprocate motion conversion surface rotation. In addition to using the cylinder or cylinder piston to drive, there is no pneumatic film driven, because of its travel and driving force is small, it is mainly used for regulating valve. Manual valve Manual valve is the most basic way of driving the valve. It consists of direct drive by handwheel, handle or wrench and drive by drive mechanism. When the valve opening torque is large, can be driven by gear or worm gear to achieve the purpose of omission. Gears drive split spur gear drive and bevel gear drive. Gear reduction ratio is small, suitable for gate valve and globe valve, worm gear drive slowdown, suitable for plug flash, ball valve and butterfly valve. Third, the main technical performance of the valve Strength performance Valve strength performance refers to the ability of the valve to withstand medium pressure. Valves are mechanical products subject to internal pressure and must therefore have sufficient strength and rigidity to ensure long term use without rupture or deformation. Sealing performance Valve sealing performance refers to the sealing of the valve to prevent leakage of the ability of the media, it is the valve of the most important technical performance indicators. There are three parts of the valve seal: opening and closing parts and valve seat seal between the two contacts; filler and the stem and packing box with the Department of the valve body and the valve cover connections. One of the leaks is called leakage before, which is commonly referred to as lax, it will affect the ability of the valve to cut off the medium. For cut-off valves, internal leakage is not allowed. After the two leaks called leakage, that is, the medium leaked from the valve to the valve. Leakage will result in material loss, pollute the environment, serious accidents will result. For flammable, toxic or radioactive media, leakage is even more not allowed, so the valve must have a reliable sealing performance. Liquid flow through the valve will result in pressure loss (both before and after the valve pressure difference), that is, the valve on the media flow has a certain resistance, the media to overcome the resistance of the valve will consume some energy. From the energy conservation considerations, the design and manufacture of valves, to minimize the resistance of the valve on the flow medium. Action performance Action sensitivity and reliability This refers to the valve for the media parameters change, respond to the sensitivity of the degree. The function sensitivity and reliability of valves with specific functions such as valves, pressure relief valves, regulating valves and other valves used to adjust the media parameters as well as safety valves and steam traps are very important technical performance indicators. Opening and Closing Force and Opening and Closing Moment The opening and closing force and opening and closing torque refer to the force or torque that must be applied when the valve is opened or closed. Close the valve, the need to make the opening and closing seat and the seat between the two sealing surface to form a certain seal than the pressure, but also to overcome the valve stem and packing between the stem and nut thread between the stem end of the bearing and Other friction parts of the friction, which must impose a certain closing force and closing torque, the valve opening and closing process, the required opening and closing force and opening and closing torque is changing, the maximum value is in the closure of the final instantaneous or open The initial instant. When designing and manufacturing valves, they should strive to reduce their closing force and closing torque. Opening and closing speed Opening and closing speed is used to complete the valve to open or close the action required to represent. General opening and closing of the valve speed is not strictly required, but some conditions on the opening and closing speed has special requirements, if any requirements quickly open or close to prevent accidents, and some require slow closure to prevent water hammer and so on, This should be considered when choosing the type of valve. ℃ less than t less than 120 ℃ valve. Fourth, the valve identification paint 1, the valve products according to the valve body material to identify the paint, the color according to the table Body material Gray iron, malleable iron Ductile iron Carbon steel Acid-resistant steel, stainless steel alloy steel Identification Paint color Black Silver Medium Gray Blue Blue Note: (1) acid-resistant steel, stainless steel is not allowed to paint (2) copper alloy is not painted 2, in order to represent the valve sealing surface material, should be in the hand wheel, handle, To identify the paint, the color according to the provisions of the table. Sealing surface material copper alloy pasteurized steel acid-resistant steel stainless steel nitrided steel boron steel hardened alloy Monel plastic rubber cast iron identification paint color red light yellow sky blue sky blue sky blue dark yellow fuchsia green black Note: (1) Seat and opening and closing pieces of sealing surface material is not the same, according to the low hardness material coloring. (2) check valve, coated on the top of the bonnet: safety valve, pressure reducing valve, trap coated on the valve cover or bonnet. 3, Transmission paint color, according to the following provisions: (1) Electric device: common type coated in gray, triple (outdoor, explosion-proof, anti-corrosion) painted blue. (2) Pneumatic, hydraulic, gear drive and other transmission mechanism, with the product coloring. Fifth, the general principles Water supply pipes on the use of the valve, the general principles of the following options: 1, diameter of not more than 50mm, it is appropriate to use the globe valve, pipe diameter greater than 50mm gate valve, butterfly valve. 2, need to adjust the flow, water pressure should be used when the control valve, globe valve. 3, requiring a small flow resistance parts (such as the pump suction pipe), should adopt the gate valve. 4, the flow should be two-way flow of pipe sections should be used gate valve, butterfly valve, shall not use the globe valve. 5, the installation of small parts should adopt the butterfly valve, ball valve. 6, often in the opening and closing of the pipe, should adopt the globe valve. 7, caliber pump outlet pipe should adopt multi-function valve. The following parts of the water supply pipe should be set on the valve: 1, residential water supply pipe from the municipal water supply pipe on the introduction of pipe. 2, residential community outdoor ring network node, should be set to separate requirements. Ring pipe is too long, it is advisable to set up segmented valves. 3, from the living quarters to the water pipe on the branch or pipe from the beginning. 4, household pipe, water meter and each branch standpipe (bottom of standpipe, vertical ring pipe stand up and down end). 5, ring pipe network of sub-trunk, through the branch pipe network connection. 6, indoor water supply pipe to households, public toilets and other access to the beginning of the distribution pipe, water distribution pipe with water points in the 3 and 3 or more settings. 7, the water pump, self-filling pump suction pump. 8, the tank into the outlet pipe, drain pipe. 9, equipment (such as heaters, cooling towers, etc.) water fill pipe. 10, plumbing fixtures (such as large, urinal, wash basin, shower, etc.) with the water pipe. 11, some of the accessories, such as automatic exhaust valve, pressure relief valve, water hammer eliminator, pressure gauge, sprinkler and other front, pressure reducing valve and backflow preventer before and after. 12, the lowest point of the water supply network should set the drain valve. First, the valve classification 1, according to the purpose and role of classification <> Shut-off valve is mainly used to cut off or connect the media flow. Including gate valve, globe valve, diaphragm valve, ball valve, plug valve, butterfly valve, plunger valve, ball valve, needle valve and so on. <> Regulating valve is mainly used to regulate the flow of media, pressure and so on. Including the control valve, throttle, pressure reducing valve. <> Check valves are used to prevent backflow of media. Includes various configurations of check valves. <> Diverter valves are used to separate, distribute or mix media. Including a variety of distribution valves and traps and other structures. <> Safety valves are used to protect the medium against overpressure. Including various types of safety valve. 2, according to the main parameters of classification (a) by pressure classification <> vacuum valve working pressure is lower than the standard atmospheric pressure valve. <> Low pressure valve Nominal pressure PN less than 1.6MPa valve. <> Medium pressure valve Nominal pressure PN 2.5 ~ 6.4MPa valve. <> High pressure valve Nominal pressure PN10.0 ~ 80.0MPa valve. <> UHP valve nominal pressure PN greater than 100MPa valve. (B) by the temperature of the medium temperature valve t greater than 450 "C of the valve."> Medium temperature valve 120 "C less than t less than 450" C valve. "> Room temperature -40" C less than t less than 120 "C Valves. <> Cryogenic Valves-100 "C Valves less than t less than -40" C. <> Cryogenic Valves t <-100 "C Valves. (C) by body material classification <> Non-metallic materials valves: such as ceramic valves, glass steel valves, plastic valves. Metal Materials Valves: such as copper alloy valve, aluminum alloy valve, lead alloy valve, titanium alloy valve, Monel alloy valve cast iron valve, carbon steel valve, cast steel valve, low alloy steel valve, high alloy steel valve. <> Metal Body Lined Valves: Lined Lead Valves, Lined Plastic Valves, Lined Enamel Valves. 3, the general taxonomy <> This classification method according to the principle, the role of structural division, is currently the most common international and domestic classification methods. General sub-gate valves, globe valves, throttle valves, instrumentation valves, plunger valves, diaphragm valves, plug valves, ball valves, butterfly valves, check valves, pressure relief valve safety valve, Sewage valve and so on. Second, how to choose the valve The choice of valves, I personally think that rather control the secondary point, the valve must be good, run, run, drip, leak, and fittings and valves are often related. When using the valve: 1, pressure reducing valve, counterbalance valve, etc. must be bypassed; 2, full open full closed with the best ball valve, gate valve; 3, try to use the globe valve; 4, valve resistance calculation should pay attention; , Electric valve must be selected. A, according to the nature of the medium-off valve butterfly valve butterfly valve installed in the pipe diameter direction. In the butterfly valve body cylindrical channel, the disc-shaped disc rotates about the axis, the rotation angle is between 0 ° ~ 90 °, when rotated to 90 °, the valve is fully open state card. Butterfly valve structure is simple, small size, light weight, only a few components. And just turn 90 ° to quickly open and close, easy to operate, while the valve has good fluid control features. When the butterfly valve is fully open, the thickness of the disc is the only resistance to the flow of the medium through the valve body, so the pressure drop across the valve is small and therefore has good flow control characteristics. Butterfly valve seal and metal seal two types of seal. Flexible sealing valves, seals can be embedded in the body or attached to the butterfly plate around. Valves with metal seals generally have a longer life than elastomeric valves, but are harder to seal completely. Metal seals can adapt to higher operating temperatures, while flexible seals have temperature-limited defects. If the butterfly valve is required to be used as a flow control, the main choice is the correct size and type of valve. The structural principle of the butterfly valve is especially suitable for making large diameter valves. Butterfly valve not only in the oil, gas, chemicals, water treatment and other general industry has been widely used, but also used in thermal power station cooling water system. Commonly used butterfly valve clamp butterfly valve and flange two. The butterfly valve on the folder is to use double-headed bolts to connect the valve between the two pipe flanges, flanged butterfly valve is equipped with a flange on the valve, with bolts on both sides of the valve flange connected to the pipe flange. Valve strength performance refers to the ability of the valve to withstand medium pressure. Valves are mechanical products subject to internal pressure and must therefore have sufficient strength and rigidity to ensure long term use without rupture or deformation. Ball valve ball valve is evolved from the plug. It has the same 90 degree rotation action, except that the plug body is a sphere with a circular through hole or passage through its axis. The ratio of the sphere to the channel should be such that when the sphere is rotated 90 degrees, the sphere should be fully spherical at the inlet and outlet to cut off the flow. Ball valve only need to rotate 90 degrees of operation and a small turning moment can be closed tight. The completely equal body cavity provides a medium-sized, straight-through runner with low resistance. Ball valves are generally considered to be the most suitable for direct opening and closing, but recent developments have designed the ball valve to be throttling and controlling flow. The main features of the ball valve is its compact structure, easy operation and maintenance, suitable for general working media such as water, solvents, acids and natural gas, but also for media with bad working conditions such as oxygen, hydrogen peroxide, methane and ethylene. Ball valve body can be a whole, it can be combined. Globe valve stem valve stem valve seat sealing surface perpendicular to. Stem opening or closing stroke is relatively short, and has a very reliable cut off action, making this valve is very suitable as a medium cut off or adjust and throttle. Once the valve flap of the globe valve is open, its contact between the valve seat and the flap sealing surface no longer contacts and has a very reliable cut-off action, making this valve ideal as a medium to cut or adjust Flow use. Once the stop valve is open, its valve seat and disc seal surface no longer have contact between, and therefore its sealing surface mechanical wear and tear less, as most of the valve seat and the disc valve is relatively easy to repair or replacement Sealing components without having to remove the entire valve from the pipeline, which for the valve and pipe welding is integrated into the case is very applicable. The flow direction of the medium as it passes through such a valve changes, so the shut-off valve has a higher flow resistance than the other valves. There are several commonly used stop valves: 1) Angular stop valves; in angle stop valves, the fluid only needs to be changed in one direction so that the pressure drop across this valve is less than that of conventional stop valves. 2) DC shut-off valve; In the DC or Y-type shut-off valve, the valve body flow path and the main flow channel into a slash, so that the flow of state damage than the conventional valve is smaller, so the pressure loss through the valve accordingly Small 3) Plunger globe valve: This type of globe valve is a variation of a conventional globe valve. In this valve, the disc and seat are usually designed based on the plunger principle. Polished valve plunger into a plunger connected with the stem, the seal is set by the plunger in the two elastic ring to achieve. The two elastomeric seals are separated by a collar, and the seal around the plunger is pressed firmly by the load exerted by the bonnet nut on the bonnet. Elastomeric seals are interchangeable and can be made in a wide variety of materials. The valves are mainly used to "open" or "close", but with a special form of plunger or special collar that can also be used to regulate flow . Valve gate valve is used as a cut-off medium, the entire circulation through the fully open, this time the pressure loss of medium operation minimum. Gate valve is usually applied to do not often need to open and close, and keep the gate fully open or fully closed conditions. Not suitable for use as a regulator or throttling. For high-speed flow media, the gate may cause gate vibration when the gate is open partially, and the vibration may damage the sealing surface of the gate and valve seat, which can cause the gate to suffer erosion of the medium. The main difference from the structural form is the form of the sealing element used. According to the form of the sealing element, the gate valve is often divided into several different types, such as wedge gate valve, parallel gate valve, parallel double gate gate valve, wedge double gate gate and the like. The most common forms are wedge gate valves and parallel gate valves. B, by preventing the media back to select the valve The role of this type of valve is to allow only medium to flow in one direction, but also to prevent the flow direction. Usually this kind of valve is automatic working, the valve flap opens under the pressure of the fluid flowing in one direction; when the fluid flows in the opposite direction, the valve flap is acted upon by the fluid pressure and the self-weight of the valve flap to cut off the flow. Which check valve belongs to this type of valve, which includes the swing check valve and lift check valve. Swing check valves have a hinged hinge mechanism and a flap-like flap freely rests against the slanted seat surface. To ensure that the valve flap reaches the proper seating surface every time, the valve flap is designed on the hinge mechanism so that the valve flap has enough swivel-open space for true and complete valve flap contact. The valve flap can be made entirely of metal, or it can be fitted with a leather, rubber or synthetic cover over the metal, depending on the performance requirements. Swing check valve in the fully open condition, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. Lift check valve seat is located on the valve seat sealing surface. In addition to the valve flap valve can be free to rise and fall, the rest of the same as the cut-off valve, the fluid pressure so that the valve flap from the valve seat lifting surface, the media back to cause the valve flap down to the seat, and cut off the flow. Depending on the conditions of use, the valve disc can be of all-metal construction or it can be in the form of a rubber gasket or rubber ring inlaid on the valve disc holder. Like the stop valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than the swing check valve and the flow through the swing check valve is limited Few. C, according to adjust the media parameters Selection of valves in the production process, in order to make the media pressure, flow and other parameters in line with the requirements of the process, the need to install the adjustment mechanism to adjust the above parameters. The main working principle of the adjusting mechanism is to change the valve disc and the flow area between the valve disc and valve seat to achieve the purpose of adjusting the above parameters. Belong to this type of valve collectively referred to as the control valve, which is divided into rely on the media itself driven by self-driven control valves such as pressure relief valves, pressure regulators, etc., where the leading power-driven (such as electricity, compressed air and liquid Power) called his drive control valves, such as electric control valve, pneumatic control valve and hydraulic control valve. D, according to the nature of the valve driven by the use of electricity-driven valves Valves are commonly used drive-driven valves, usually referred to as the drive device for the valve actuator, valve electric device features are as follows: 1) quick opening and closing , Can greatly shorten the time required to open and close the valve; 2) can greatly reduce the labor intensity of the operator, especially for high pressure, large diameter valves; 3) Suitable for installation in the position can not be manually operated or difficult to achieve, easy to implement far 4) facilitate automation of the entire system; 5) Power sources are more readily available than air and liquid sources, and their wiring is easier to lay and maintain than compressed air and hydraulic lines. The disadvantage of valve electric devices is the complex structure, more difficult to use in wet places, when used in explosive media, the need to use explosion-proof measures. Valve actuators driven by the valve type is different, can be divided into two types of Z and Q type. Z-type valve electric device output shaft can turn out a lot of laps, suitable for driving gate valves, globe valves, diaphragm valves; Q-type valve electric device output shaft can only rotate 90. , Suitable for driving plug valves, ball valves and butterfly valves. According to the type of protection are ordinary type, flameproof type (B), heat-resistant type (R) and triple type (that is, outdoor, anti-corrosion, flameproof, Valve electric devices generally by the transmission (gear), motor, travel control agencies, torque limit agencies, manual - electric switching mechanism, opening indicator and other components. Pneumatic and hydraulic valves Pneumatic valves and hydraulic is a certain pressure of air, water or oil as the power source, the use of the cylinder (or hydraulic cylinder) and piston movement to drive the valve, the general pneumatic pressure of air is less than 0.8MPa, the liquid Dynamic pressure or hydraulic pressure is 2.5MPa ~ 25MPa. Or diaphragm valve; rotary gas and liquid drive device for driving the ball valve, butterfly valve or plug valve. The driving force of hydraulic device is large, suitable for driving large-caliber valves. Such as used to drive the plug valve, ball valve and butterfly valve, the piston must reciprocate motion conversion surface rotation. In addition to using the cylinder or cylinder piston to drive, there is no pneumatic film driven, because of its travel and driving force is small, it is mainly used for regulating valve. Manual valve Manual valve is the most basic way of driving the valve. It consists of direct drive by handwheel, handle or wrench and drive by drive mechanism. When the valve opening torque is large, can be driven by gear or worm gear to achieve the purpose of omission. Gears drive split spur gear drive and bevel gear drive. Gear reduction ratio is small, suitable for gate valve and globe valve, worm gear drive slowdown, suitable for plug flash, ball valve and butterfly valve. Third, the main technical performance of the valve Strength performance Valve strength performance refers to the ability of the valve to withstand medium pressure. Valves are mechanical products subject to internal pressure and must therefore have sufficient strength and rigidity to ensure long term use without rupture or deformation. Sealing performance Valve sealing performance refers to the sealing of the valve to prevent leakage of the ability of the media, it is the valve of the most important technical performance indicators. There are three parts of the valve seal: opening and closing parts and valve seat seal between the two contacts; filler and the stem and packing box with the Department of the valve body and the valve cover connections. One of the leaks is called leakage before, which is commonly referred to as lax, it will affect the ability of the valve to cut off the medium. For cut-off valves, internal leakage is not allowed. After the two leaks called leakage, that is, the medium leaked from the valve to the valve. Leakage will result in material loss, pollute the environment, serious accidents will result. For flammable, toxic or radioactive media, leakage is even more not allowed, so the valve must have a reliable sealing performance. Liquid flow through the valve will result in pressure loss (both before and after the valve pressure difference), that is, the valve on the media flow has a certain resistance, the media to overcome the resistance of the valve will consume some energy. From the energy conservation considerations, the design and manufacture of valves, to minimize the resistance of the valve on the flow medium. Action performance Action sensitivity and reliability This refers to the valve for the media parameters change, respond to the sensitivity of the degree. The function sensitivity and reliability of valves with specific functions such as valves, pressure relief valves, regulating valves and other valves used to adjust the media parameters as well as safety valves and steam traps are very important technical performance indicators. Opening and Closing Force and Opening and Closing Moment The opening and closing force and opening and closing torque refer to the force or torque that must be applied when the valve is opened or closed. Close the valve, the need to make the opening and closing seat and the seat between the two sealing surface to form a certain seal than the pressure, but also to overcome the valve stem and packing between the stem and nut thread between the stem end of the bearing and Other friction parts of the friction, which must impose a certain closing force and closing torque, the valve opening and closing process, the required opening and closing force and opening and closing torque is changing, the maximum value is in the closure of the final instantaneous or open The initial instant. When designing and manufacturing valves, they should strive to reduce their closing force and closing torque. Opening and closing speed Opening and closing speed is used to complete the valve to open or close the action required to represent. General opening and closing of the valve speed is not strictly required, but some conditions on the opening and closing speed has special requirements, if any requirements quickly open or close to prevent accidents, and some require slow closure to prevent water hammer and so on, This should be considered when choosing the type of valve. ℃ less than t less than 120 ℃ valve. Fourth, the valve identification paint 1, the valve products according to the valve body material to identify the paint, the color according to the table Body material Gray iron, malleable iron Ductile iron Carbon steel Acid-resistant steel, stainless steel alloy steel Identification Paint color Black Silver Medium Gray Blue Blue Note: (1) acid-resistant steel, stainless steel is not allowed to paint (2) copper alloy is not painted 2, in order to represent the valve sealing surface material, should be in the hand wheel, handle, To identify the paint, the color according to the provisions of the table. Sealing surface material copper alloy pasteurized steel acid-resistant steel stainless steel nitrided steel boron steel hardened alloy Monel plastic rubber cast iron identification paint color red light yellow sky blue sky blue sky blue dark yellow fuchsia green black Note: (1) Seat and opening and closing pieces of sealing surface material is not the same, according to the low hardness material coloring. (2) check valve, coated on the top of the bonnet: safety valve, pressure reducing valve, trap coated on the valve cover or bonnet. 3, Transmission paint color, according to the following provisions: (1) Electric device: common type coated in gray, triple (outdoor, explosion-proof, anti-corrosion) painted blue. (2) Pneumatic, hydraulic, gear drive and other transmission mechanism, with the product coloring. Fifth, the general principles Water supply pipes on the use of the valve, the general principles of the following options: 1, diameter of not more than 50mm, it is appropriate to use the globe valve, pipe diameter greater than 50mm gate valve, butterfly valve. 2, need to adjust the flow, water pressure should be used when the control valve, globe valve. 3, requiring a small flow resistance parts (such as the pump suction pipe), should adopt the gate valve. 4, the flow should be two-way flow of pipe sections should be used gate valve, butterfly valve, shall not use the globe valve. 5, the installation of small parts should adopt the butterfly valve, ball valve. 6, often in the opening and closing of the pipe, should adopt the globe valve. 7, caliber pump outlet pipe should adopt multi-function valve. The following parts of the water supply pipe should be set on the valve: 1, residential water supply pipe from the municipal water supply pipe on the introduction of pipe. 2, residential community outdoor ring network node, should be set to separate requirements. Ring pipe is too long, it is advisable to set up segmented valves. 3, from the living quarters to the water pipe on the branch or pipe from the beginning. 4, household pipe, water meter and each branch standpipe (bottom of standpipe, vertical ring pipe stand up and down end). 5, ring pipe network of sub-trunk, through the branch pipe network connection. 6, indoor water supply pipe to households, public toilets and other access to the beginning of the distribution pipe, water distribution pipe with water points in the 3 and 3 or more settings. 7, the water pump, self-filling pump suction pump. 8, the tank into the outlet pipe, drain pipe. 9, equipment (such as heaters, cooling towers, etc.) water fill pipe. 10, plumbing fixtures (such as large, urinal, wash basin, shower, etc.) with the water pipe. 11, some of the accessories, such as automatic exhaust valve, pressure relief valve, water hammer eliminator, pressure gauge, sprinkler and other front, pressure reducing valve and backflow preventer before and after. 12, the lowest point of the water supply network should set the drain valve.