Introduction to commonly used valves

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Valves are pipeline accessories, used to open and close pipelines and control the flow of fluid media in pipelines. The functions of valves in pipelines include shutoff, regulation, flow diversion, prevention of reverse flow, pressure stabilization, flow diversion or overflow pressure relief, etc. There are many types of valves. As control components of fluid control systems, there are many varieties and specifications, from the simplest common valves such as butterfly valves and gate valves to various valves used in extremely complex automatic control systems.

Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media, and are used in various industries. Although there are many types of valves, what are the commonly used valves? This article will introduce you one by one:

There are five commonly used valves: butterfly valve, gate valve, check valve, ball valve, and globe valve.

butterfly valve

Butterfly valve, also known as flap valve, is a regulating valve with a simple structure and easy to use. The butterfly plate in the valve body of the butterfly valve is the closing part of the valve. It is disk-shaped. The working principle is that the butterfly plate rotates around the valve axis to realize the valve's opening. Opening and closing, usually, the butterfly plate is driven by the valve stem and rotates 90° to complete one opening and closing to achieve the purpose of intercepting flow. If the deflection angle of the butterfly plate is changed, it can also be used as a flow control. Normally, butterfly valves are commonly used for switching control of low-pressure pipeline media.

Wafer-type butterfly valve and flange-type butterfly valve are two connection forms of butterfly valves. Butterfly valves are suitable for making large-diameter valves and are suitable for natural gas, liquefied petroleum gas, city gas, hot and cold air, chemical smelting, power generation, environmental protection, building water supply and drainage and other projects. It is used to regulate and cut off the flow of media on pipelines that transport various corrosive and non-corrosive fluid media in the system.

gate

Gate valves are usually used to cut off flow in pipeline systems. Its opening and closing parts are gate plates. The movement direction of the gate plate is perpendicular to the direction of the flow of the medium in the pipeline. When the gate plate rises, the valve opens to realize the flow of the pipeline medium; when the gate plate falls, The valve is closed and the pipeline medium flow is cut off. The gate valve can only be fully opened or fully closed, and is used to cut off the flow of media. It cannot be adjusted or throttled. Therefore, gate valves are generally used in pipeline environments that keep the gate valve gate fully open and fully closed, and do not require frequent opening and closing.

Gate valves can be divided into wedge gate valves and parallel gate valves according to different gate plate structures. Wedge gate valves can be divided into three types: single gate valve, double gate valve and elastic gate valve.

Check valve

Check valve, also known as unidirectional valve or check valve, is an automatic valve, which means that the check valve works automatically and does not require manual operation. When the medium flows through the check valve, under the pressure impact of the fluid medium, the check valve The valve disc of the return valve opens automatically to allow the medium to pass through; after the medium flow is cut off, the valve disc automatically closes under the force of its own spring device to prevent the medium from flowing back and backflowing.

Check valves are only suitable for installation in pipelines where the medium flows in one direction. The main function is to prevent the backflow of the medium, the reverse rotation of the pump and the driving motor, and the discharge of the container medium.

Shut-off valve

The stop valve, also known as the stop valve, is a forced sealing valve. That is to say, unlike the automatic operation of the check valve, when the stop valve is closed, pressure must be applied to the valve disc to force the sealing surface not to leak. When the medium enters the valve from below the valve disc, the flow direction changes, so the resistance that needs to be overcome to operate the stop valve is the friction between the valve stem and the packing, the thrust generated by the pressure of the medium, and the force to close the valve. It is larger than the force required to open the valve, so the diameter of the valve stem must be larger, otherwise the valve stem will bend. The flow resistance of the stop valve is higher than that of other valves.

Stop valves can be used to cut off media like gate valves, but more often, people use stop valves to regulate flow.

ball valve

Ball valves evolved from rotary valves. It is similar to a butterfly valve in that it also needs to be rotated 90 degrees to open and close. The difference is that the butterfly valve has a butterfly plate, while the ball valve has a spherical plug body with a circular through hole or channel passing through its axis.

The ball valve can cut off, distribute and change the flow direction of the medium in the pipeline. It only needs to be rotated 90 degrees and a small rotational torque to close tightly. Therefore, ball valves are most suitable for use as switches and cut-off valves. It has been widely used in petroleum refining, long-distance pipelines, chemical industry, papermaking and other industries.