Abstract: In the heating system, the valve is common to be seen and there are many types. Its main function is to control the flow of the medium, and play a role in assisting the pipeline work. Valves of high quality and suitable types can ensure the normal and safe operation of heating projects.
The valve is the key control part in the fluid conveying system. The problems of medium control, diversion and closing in the heating engineering all depend on the control of the valve part. There are two main functions of the valve: as the main device, it plays the role of closing; as the auxiliary device, it plays the role of auxiliary work.
1. Classifications and uses of valves commonly used in heating engineering
There are many types of valves commonly used in heating systems, such as balance valves, self-supporting balance valves, gate valves, ball valves, butterfly valves, safety valves, globe valves, check valves, regulating valves, etc. They have different characteristics and play different roles in heating engineering. The classifications and uses of these valves will be analyzed in detail below.
(1) Balance valves
The balancing valve improves its flow channel pattern on the basis of the regulating valve and enhances the functionality of the regulating valve, so it is also called an improved regulating valve or an enhanced version of the regulating valve. The main improvement of the balance valve is reflected in the two parts of the flow channel mode and the valve seat material. The flow channel adopts the direct flow type, which can be applied to the heating project with large capacity. The valve seat adopts PTFE. The improved balance valve has the characteristics of small low resistance, better sealing when applied to large-capacity heating projects, and also has a function of cutting off. The balance valve has an excellent flow adjustment function when used in the secondary pipelines of the thermal station in the heating system. It is precise because of its enhanced control over the medium that the balance valve can be used in more variable flow systems. It should be noted that the directionality of the balancing valve needed to be paid attention to when installing it, and whether to install it vertically or horizontally should be according to the specific needs of the project.
(2) Self-operated balancing valves
A structure composed of springs and rubber films is installed for self-balancing valves, and the valve stem is connected to this structure. The self-operated balancing valve is an enhanced version of the balancing valve. Its characteristic is that it strengthens the control of the medium flow, and is generally used in heating projects with a relatively large flow. When the flow increases, its impact on the balance valve will create an unbalanced force, which will cause the disc to gradually move in the closing direction. The greater the force of the media flow is, the more the disc moves in the closing direction. The process of the valve disc gradually moving in the closing direction is the process of reducing the flow area. Generally, a fixed value is set inside the valve, which is the maximum position of the valve disc moving in the closing direction. Therefore, no matter how great the flow rate is in the heating project, the maximum flow rate that the self-operated valve can pass through is fixed. The purpose of setting the self-supporting balance valve is to control the flow in the heating project and automatically eliminate the problem of hydraulic imbalance. The self-operated balancing valve is also directional, so be careful not to install it in the opposite direction during installation.
(3) Gate valves
The purpose of setting the balance valve and the self-balancing method is to control the medium flow in the heating project, and it is often used in the heating project with a relatively large medium flow. The most common valve in heating engineering is the gate valve. The principle of a gate valve is that the wedge and the gate seat have the same height, and a sealing pair plate is formed. By lifting and pressing the stem on the gate valve, the medium is intercepted or not intercepted. Therefore, the gate valve acts as a function of shutting off in the working process. The gate valve has many advantages. In the heating project, the medium flow encounters less resistance at the wedge, so it can also ensure that the sealing surface will not be scoured by the medium when it is fully opened. Moreover, the gate valve can be used normally under the condition of a two-way flow of heating engineering medium.
In the installation process, the gate valve is not directional. The material of the gate valve is relatively strong and durable, and it is not easy to be damaged. It can be used not only in heating projects with a relatively small medium flow, but also in large medium flow. The gate valve is a common valve with high-cost performance and the best performance, so it is used more in heating engineering. According to the different forms of the valve stem, the gate valve can be divided into two types, that is, rising stem gate valves and non-rising stem gate valves. According to the different structure of the wedge, a gate valve can be divided into parallel and wedge gate valves, and the wedge type is more commonly used than the parallel type. Parallel and wedge gate valves can be further divided into a single wedge and double wedge gate valves. Rising stem single wedge gate valves and non-rising stem wedge gate valves are used often in heating engineering. The former is mostly installed on the primary side of the thermal power station, while the latter is generally installed on the secondary side of the thermal power station. Usually, it is installed next to the main equipment, which plays the function of maintenance. The engineer needs to choose whether to use the gate valve as the control key of the heating project according to the actual situation.
However, gate valves also have shortcomings. For example, the gate valve is tall, so if the space conditions of the heating project do not allow it, it cannot be used. The time required for the opening and closing of the gate valve is too long, and the engineer must judge the working time of the heating system. If it is a heating project that requires emergency control, it is not suitable to use a gate valve. The valve seat and valve plate of the gate valve are integrated. The gate valve is relatively heavy compared to other valves. The repair process is cumbersome and difficult. If it is a large-diameter gate valve, it is difficult to operate manually it, so it is generally controlled by semi-automatic or fully automatic operation. When installing the gate valve, it should be noted that the handwheel should not be installed below the parallel line; otherwise, the long-term impact and corrosion of the medium will corrode the valve stem.
The valve is the key control part in the fluid conveying system. The problems of medium control, diversion and closing in the heating engineering all depend on the control of the valve part. There are two main functions of the valve: as the main device, it plays the role of closing; as the auxiliary device, it plays the role of auxiliary work.
1. Classifications and uses of valves commonly used in heating engineering
There are many types of valves commonly used in heating systems, such as balance valves, self-supporting balance valves, gate valves, ball valves, butterfly valves, safety valves, globe valves, check valves, regulating valves, etc. They have different characteristics and play different roles in heating engineering. The classifications and uses of these valves will be analyzed in detail below.
(1) Balance valves
The balancing valve improves its flow channel pattern on the basis of the regulating valve and enhances the functionality of the regulating valve, so it is also called an improved regulating valve or an enhanced version of the regulating valve. The main improvement of the balance valve is reflected in the two parts of the flow channel mode and the valve seat material. The flow channel adopts the direct flow type, which can be applied to the heating project with large capacity. The valve seat adopts PTFE. The improved balance valve has the characteristics of small low resistance, better sealing when applied to large-capacity heating projects, and also has a function of cutting off. The balance valve has an excellent flow adjustment function when used in the secondary pipelines of the thermal station in the heating system. It is precise because of its enhanced control over the medium that the balance valve can be used in more variable flow systems. It should be noted that the directionality of the balancing valve needed to be paid attention to when installing it, and whether to install it vertically or horizontally should be according to the specific needs of the project.
(2) Self-operated balancing valves
A structure composed of springs and rubber films is installed for self-balancing valves, and the valve stem is connected to this structure. The self-operated balancing valve is an enhanced version of the balancing valve. Its characteristic is that it strengthens the control of the medium flow, and is generally used in heating projects with a relatively large flow. When the flow increases, its impact on the balance valve will create an unbalanced force, which will cause the disc to gradually move in the closing direction. The greater the force of the media flow is, the more the disc moves in the closing direction. The process of the valve disc gradually moving in the closing direction is the process of reducing the flow area. Generally, a fixed value is set inside the valve, which is the maximum position of the valve disc moving in the closing direction. Therefore, no matter how great the flow rate is in the heating project, the maximum flow rate that the self-operated valve can pass through is fixed. The purpose of setting the self-supporting balance valve is to control the flow in the heating project and automatically eliminate the problem of hydraulic imbalance. The self-operated balancing valve is also directional, so be careful not to install it in the opposite direction during installation.
(3) Gate valves
The purpose of setting the balance valve and the self-balancing method is to control the medium flow in the heating project, and it is often used in the heating project with a relatively large medium flow. The most common valve in heating engineering is the gate valve. The principle of a gate valve is that the wedge and the gate seat have the same height, and a sealing pair plate is formed. By lifting and pressing the stem on the gate valve, the medium is intercepted or not intercepted. Therefore, the gate valve acts as a function of shutting off in the working process. The gate valve has many advantages. In the heating project, the medium flow encounters less resistance at the wedge, so it can also ensure that the sealing surface will not be scoured by the medium when it is fully opened. Moreover, the gate valve can be used normally under the condition of a two-way flow of heating engineering medium.
In the installation process, the gate valve is not directional. The material of the gate valve is relatively strong and durable, and it is not easy to be damaged. It can be used not only in heating projects with a relatively small medium flow, but also in large medium flow. The gate valve is a common valve with high-cost performance and the best performance, so it is used more in heating engineering. According to the different forms of the valve stem, the gate valve can be divided into two types, that is, rising stem gate valves and non-rising stem gate valves. According to the different structure of the wedge, a gate valve can be divided into parallel and wedge gate valves, and the wedge type is more commonly used than the parallel type. Parallel and wedge gate valves can be further divided into a single wedge and double wedge gate valves. Rising stem single wedge gate valves and non-rising stem wedge gate valves are used often in heating engineering. The former is mostly installed on the primary side of the thermal power station, while the latter is generally installed on the secondary side of the thermal power station. Usually, it is installed next to the main equipment, which plays the function of maintenance. The engineer needs to choose whether to use the gate valve as the control key of the heating project according to the actual situation.
However, gate valves also have shortcomings. For example, the gate valve is tall, so if the space conditions of the heating project do not allow it, it cannot be used. The time required for the opening and closing of the gate valve is too long, and the engineer must judge the working time of the heating system. If it is a heating project that requires emergency control, it is not suitable to use a gate valve. The valve seat and valve plate of the gate valve are integrated. The gate valve is relatively heavy compared to other valves. The repair process is cumbersome and difficult. If it is a large-diameter gate valve, it is difficult to operate manually it, so it is generally controlled by semi-automatic or fully automatic operation. When installing the gate valve, it should be noted that the handwheel should not be installed below the parallel line; otherwise, the long-term impact and corrosion of the medium will corrode the valve stem.
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