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Heating valve commonly used valve classification and use of each category

There are many types of valves and they have a wide range of applications. Sometimes it is the main equipment in the pipeline and plays a controlling role; sometimes it is a minor equipment and plays an auxiliary role. If it is used improperly, there will be "running, running, dripping, and leaking" phenomena, lighter ones affecting production, and the most serious ones causing accidents. So understanding and using the valve correctly is a very important issue.
1. Valve classification
There are many types of valves used in heating systems. Such as gate valve, globe valve, ball valve, butterfly valve, check valve, safety valve, regulating valve, balancing valve, self-balancing valve and so on. Introduced one by one below.
1.1 Gate valve
Also called gate valve, gate valve, is a widely used valve.
Working principle: The sealing surface of the gate plate and the sealing surface of the valve seat are highly smooth, flat and uniform, and processed into a very close and tight sealing pair. The gate is turned on and off through the lifting and pressing of the valve stem. It acts as a shut-off in the pipeline.
Advantages: Small fluid resistance; Sealed surface free from erosion when fully open; Can be used in the case of two-way flow of the medium, no directional; Durable; Not only suitable for small valves, but also large valves.
Disadvantages: high height; long opening and closing time; bulky; difficult to repair; if it is a large-diameter gate valve, manual operation is more laborious.
Gate valve according to the different stem and rod rod type distinct; according to the gate structure of different points parallel and wedge type; there are single gate, double gate board points. In heating engineering, commonly used is a single wedge gate valve (Z41H-16C) and a single wedge gate valve (Z45T-10). The former is installed on the primary side of the thermal station, and the latter is installed in the thermal station. Secondary side. It generally serves two functions: it acts as a master switch; it serves as an auxiliary device for maintenance before and after the master device.
When the gate valve is installed, do not make the handwheel below the horizontal line (flip), otherwise the medium will remain in the valve cover for a long time and the valve stem will easily corrode. In the heating project, the gate valve was once the main force in the valve. Now with the widespread adoption of butterfly valves, gate valves have been replaced by butterfly valves.
1.2 stop valve
It is also a widely used valve. The general diameter is below 100mm. Its working principle is similar to that of a gate valve except that the closing member (valve) moves along the centerline of the valve seat. It acts as a shut-off in the pipeline and can also regulate the flow roughly.
Advantages: easy to manufacture, easy to maintain, strong and durable.
Disadvantages: Only allows media to flow in one direction, and has directionality when installed. Large flow resistance, poor sealing.
According to the structure, it is divided into straight-through, right-angle, direct-current and balanced. Flange straight-through (J41H) and female thread straight-through (J11H) are generally used in the project. The globe valve has directionality and cannot be reversed. It should not be down.
In our production and life, past straight-through, small-diameter globe valves have been used in the past and have now gradually been replaced by ball valves.
1.3 Ball valve
Compared with gate valves and globe valves, ball valves are new and increasingly widely used valves. Its working principle is: The valve core is a sphere with a through cavity, and the valve core is controlled by the valve stem to make a 90° rotation so that the valve can be blocked or blocked. It acts as a shut-off in the pipeline.
Advantages: In addition to the advantages of gate valve and globe valve, there are advantages of small size, good sealing (zero leakage), and easy operation. Currently widely used in petrochemical, power, nuclear, aviation, aerospace and other sectors
Disadvantages: difficult to maintain.
There are two types of ball valves: floating ball and fixed ball. In the heating project, some key positions, such as the important branch, the population of the thermal station, DN250, often use imported ball valve. It is different from the structure of the domestic ball valve: the valve body of the domestic ball valve is generally two-piece, three-piece, flange connection; while the valve body of the imported ball valve is one-piece, welded connection, the fault point is less. Its origin is in developed countries such as Scandinavia such as Finland and Denmark. Such as Finland's NAVAL, VEXVE, Danish DAFOSS and so on. Due to its excellent sealing and reliability of operation, it has long been popular with users. The ball valve has no direction and can be installed at any angle. When the welding ball valve is installed horizontally, the valve must be opened to avoid the electric sparks during welding from injuring the surface of the ball. When installing on a vertical pipe, if the interface is welded, the valve must be opened. If the lower interface is welded, the valve must be closed to avoid the valve inside. Burned by high heat.
1.4 Butterfly valve
In the heating system, it is currently the most widely used type of valve.
Working principle: The valve disc is a disc, which rotates through the valve rod and rotates the valve disc at 90°C within the valve seat to realize the valve switching. It acts as a shut-off in the pipeline.
Can also adjust the flow.
Advantages: simple structure, light weight, easy operation, good sealing.
Disadvantages: When fully open, the valve plate (sealing ring) is eroded by the medium.
In the heating project, the butterfly valve used has three eccentric metal seal butterfly valves and rubber soft seal butterfly valves.
1.4.1 Three Offset Metal Sealing Butterfly Valve
The so-called "triple eccentricity" refers to the displacement of the valve shaft and valve plate relative to each other within the valve. Ordinary butterfly valve is an eccentric, that is, the valve shaft center line and the sealing surface centerline (valve plate centerline) deviation; high-performance plus an eccentric, that valve shaft centerline and valve centerline (pipe centerline) deviation; The purpose of double eccentricity is to open the valve plate to 20° and the seal pairs disengage from each other, reducing friction (cam effect). The triple eccentric butterfly valve adds a unique eccentric-tapering cone on the basis of the double eccentricity mentioned above, that is, the displacement of the valve plate (the sealing surface is inclined at an angle to the vertical plane of the pipe). This allows the valve to completely disengage between the seals within a 90° travel range. This not only enhances the cam effect, but also eliminates the friction completely. At the same time when the valve is closed, the seal pair gradually closes, resulting in a “wedge effect” with minimal Torque achieves the tightest shut-off.
The so-called "metal seal" means that the valve seat and the seal ring are made of a high-quality alloy that is resistant to wear, corrosion, and high temperatures. At the same time, in order to prevent the seal ring and the valve seat from colliding hard, the seal pair is designed to be in flexible contact, ie, to form an "elasticity". "Metal seal" to ensure close and open frictionless. With the "three eccentric" structure, supplemented by "elastic metal seals", such valves are light, durable, and well-sealed.
Tri-eccentric metal-sealed butterfly valves are commonly used on main lines and main branches of heating systems. The caliber is DN300 or more.
Imports of three eccentric gold abstract: This article briefly describes the principle, characteristics and usage essentials of frequently asked doors in heating engineering.
Key words: seal pair; directional; three eccentric; installation
There are many types of valves and they have a wide range of applications. Sometimes it is the main equipment in the pipeline and plays a controlling role; sometimes it is a minor equipment and plays an auxiliary role. If it is used improperly, there will be "running, running, dripping, and leaking" phenomena, lighter ones affecting production, and the most serious ones causing accidents. So understanding and using the valve correctly is a very important issue. 1. Valve classification
There are many types of valves used in heating systems. Such as gate valve, globe valve, ball valve, butterfly valve, check valve, safety valve, regulating valve, balancing valve, self-balancing valve and so on. Introduced one by one below.
1.1 Gate valve
Also called gate valve, gate valve, is a widely used valve.
Working principle: The sealing surface of the gate plate and the sealing surface of the valve seat are highly smooth, flat and uniform, and processed into a very close and tight sealing pair. The gate is turned on and off through the lifting and pressing of the valve stem. It acts as a shut-off in the pipeline.
Advantages: Small fluid resistance; Sealed surface free from erosion when fully open; Can be used in the case of two-way flow of the medium, no directional; Durable; Not only suitable for small valves, but also large valves.
Disadvantages: high height; long opening and closing time; bulky; difficult to repair; if it is a large-diameter gate valve, manual operation is more laborious.
Gate valve according to the different stem and rod rod type distinct; according to the gate structure of different points parallel and wedge type; there are single gate, double gate board points. In heating engineering, commonly used is a single wedge gate valve (Z41H-16C) and a single wedge gate valve (Z45T-10). The former is installed on the primary side of the thermal station, and the latter is installed in the thermal station. Secondary side. It generally serves two functions: it acts as a master switch; it serves as an auxiliary device for maintenance before and after the master device.
When the gate valve is installed, do not make the handwheel below the horizontal line (flip), otherwise the medium will remain in the valve cover for a long time and the valve stem will easily corrode. In the heating project, the gate valve was once the main force in the valve. Now with the widespread adoption of butterfly valves, gate valves have been replaced by butterfly valves. 1.2 stop valve
It is also a widely used valve. The general diameter is below 100mm. Its working principle is similar to that of a gate valve except that the closing member (valve) moves along the centerline of the valve seat. It acts as a shut-off in the pipeline and can also regulate the flow roughly.
Advantages: easy to manufacture, easy to maintain, strong and durable.
Disadvantages: Only allows media to flow in one direction, and has directionality when installed. Large flow resistance, poor sealing.
According to the structure, it is divided into straight-through, right-angle, direct-current and balanced. Flange straight-through (J41H) and female thread straight-through (J11H) are generally used in the project. The globe valve has directionality and cannot be reversed. It should not be down.
In our production and life, past straight-through, small-diameter globe valves have been used in the past and have now gradually been replaced by ball valves.
1.3 Ball valve
Compared with gate valves and globe valves, ball valves are new and increasingly widely used valves. Its working principle is: The valve core is a sphere with a through cavity, and the valve core is controlled by the valve stem to make a 90° rotation so that the valve can be blocked or blocked. It acts as a shut-off in the pipeline.
Advantages: In addition to the advantages of gate valve and globe valve, there are advantages of small size, good sealing (zero leakage), and easy operation. Currently widely used in petrochemical, power, nuclear energy, aviation, aerospace and other sectors. Disadvantages: difficult to maintain.
There are two types of ball valves: floating ball and fixed ball. In the heating project, some key positions, such as the important branch, the population of the thermal station, DN250, often use imported ball valve. It is different from the structure of the domestic ball valve: the valve body of the domestic ball valve is generally two-piece, three-piece, flange connection; while the valve body of the imported ball valve is one-piece, welded connection, the fault point is less. Its origin is in developed countries such as Scandinavia such as Finland and Denmark. Such as Finland's NAVAL, VEXVE, Danish DAFOSS and so on. Due to its excellent sealing and reliability of operation, it has long been popular with users. The ball valve has no direction and can be installed at any angle. When the welding ball valve is installed horizontally, the valve must be opened to avoid the electric sparks during welding from injuring the surface of the ball. When installing on a vertical pipe, if the interface is welded, the valve must be opened. If the lower interface is welded, the valve must be closed to avoid the valve inside. Burned by high heat. 1.4 Butterfly valve
In the heating system, it is currently the most widely used type of valve.
Working principle: The valve disc is a disc, which rotates through the valve rod and rotates the valve disc at 90°C within the valve seat to realize the valve switching. It acts as a shut-off in the pipeline.
Can also adjust the flow.
Advantages: simple structure, light weight, easy operation, good sealing.
Disadvantages: When fully open, the valve plate (sealing ring) is eroded by the medium.
In the heating project, the butterfly valve used has three eccentric metal seal butterfly valves and rubber soft seal butterfly valves.
1.4.1 Three Offset Metal Sealing Butterfly Valve
The so-called "triple eccentricity" refers to the displacement of the valve shaft and valve plate relative to each other within the valve. Ordinary butterfly valve is an eccentric, that is, the valve shaft center line and the sealing surface centerline (valve plate centerline) deviation; high-performance plus an eccentric, that valve shaft centerline and valve centerline (pipe centerline) deviation; The purpose of double eccentricity is to open the valve plate to 20° and the seal pairs disengage from each other, reducing friction (cam effect). The triple eccentric butterfly valve adds a unique eccentric-tapering cone on the basis of the double eccentricity mentioned above, that is, the displacement of the valve plate (the sealing surface is inclined at an angle to the vertical plane of the pipe). This allows the valve to completely disengage between the seals within a 90° travel range. This not only enhances the cam effect, but also eliminates the friction completely. At the same time when the valve is closed, the seal pair gradually closes, resulting in a “wedge effect” with minimal Torque achieves the tightest shut-off.
The so-called "metal seal" means that the valve seat and the seal ring are made of a high-quality alloy that is resistant to wear, corrosion, and high temperatures. At the same time, in order to prevent the seal ring and the valve seat from colliding hard, the seal pair is designed to be in flexible contact, ie, to form an "elasticity". "Metal seal" to ensure close and open frictionless. With the "three eccentric" structure, supplemented by "elastic metal seals", such valves are light, durable, and well-sealed.
Tri-eccentric metal-sealed butterfly valves are commonly used on main lines and main branches of heating systems. The caliber is DN300 or more.
The imported three-offset metal seal butterfly valve has no directionality, but generally there are recommended installation directions, and it is not recommended to reverse-install; domestically produced directional, generally one reverse direction is worse than the positive one or two to one pressure level, and it cannot be reversed. If welding on a horizontal pipe, the valve should be closed to protect the sealing ring; if it is welded on a vertical pipe, the valve should be closed, and the valve plate should be filled with water during welding to extinguish the welding slag. When installing on a horizontal pipe, it is recommended that the valve stem be horizontal or inclined with respect to the vertical to ensure the bottom bearing is clean.
, Should not be reverse loaded; domestically produced directional, the general reverse than the positive difference of a leak level or poor one to two pressure levels, can not be reversed. If welding on a horizontal pipe, the valve should be closed to protect the sealing ring; if it is welded on a vertical pipe, the valve should be closed, and the valve plate should be filled with water during welding to extinguish the welding slag. When installing on a horizontal pipe, it is recommended that the valve stem be horizontal or inclined with respect to the vertical to ensure the bottom bearing is clean.

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