Could an expert explain the working principles of globe valves and butterfly valves?

For example, consider a water tank with a lid: water enters from the bottom of the tank and flows out through the opening at the top; the lid functions as the closing element of a valve. If the lid is lifted upward by hand, this corresponds to the working principle of a globe valve. If the lid is moved to the side by hand, it operates like a gate valve. Main standards: 1. Design standard: GB/T 12235 2. Connection standards: 1) Butt-welded end BW: in accordance with GB/T 12224 2) Flanged end RF: in accordance with JB79； GB/T 9113 ； HG20592 3. Valve inspection and testing: GB/T 13927; JB/T 9092. It adopts the following structure: stem-mounted type with a valve cover connected by bolts ； Internal pressure self-tightening valve cover, integral upper sealing seat – Detailed description: The operating element of a globe valve is a cylindrical valve disc; its sealing surface is either flat or conical, and the valve disc moves in a straight line along the centerline of the fluid. The movement pattern of the valve stem can be of the lift-type (where the valve stem moves up and down while the handwheel does not move), or it can be of the lift-rotation type (where both the handwheel and the valve stem rotate and move up and down, with the nut being mounted on the valve body). Stop valves are only suitable for full open and full closed positions; customization allows for regulation and throttling. 　　When the stop valve is opened, the flow rate reaches its maximum when the opening height of the valve disc is 25% to 30% of the nominal diameter, indicating that the valve has reached its fully open position. Therefore, the fully open position of the stop valve should be determined by the travel of the valve disc. :) The disc of the butterfly valve is installed in the diameter direction of the pipeline. Within the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around its axis, with an angle of rotation ranging from 0° to 90°; when it reaches 90°, the valve is in its fully open position. Butterfly valves have a simple structure, are small in size and light in weight, consisting of only a few components. Moreover, it can be quickly opened and closed by just a 90° rotation, making operation simple; at the same time, this valve boasts excellent fluid control properties. When the butterfly valve is in its fully open position, the thickness of the butterfly disc is the only resistance to the flow of the medium through the valve body; as a result, the pressure drop across this valve is very small, giving it excellent flow control properties. Butterfly valves come in two types of sealing: elastic sealing and metal sealing. Elastic-sealing valves, where the sealing ring can be embedded in the valve body or attached around the butterfly disc. Valves with metal seals generally have a longer lifespan than those with elastic seals, but it is difficult to achieve a perfect seal. Metal seals can withstand higher operating temperatures, while elastic seals have the drawback of being limited by temperature. If a butterfly valve is to be used for flow control, the key is to select the correct size and type of valve. The structural principle of butterfly valves makes them particularly suitable for manufacturing large-diameter valves. Butterfly valves are widely used not only in general industries such as petroleum, gas, chemicals, and water treatment, but also in the cooling water systems of thermal power plants. The commonly used butterfly valves are wafer-type butterfly valves and flanged butterfly valves. A wafer butterfly valve is connected between two pipe flanges using bolts, while a flanged butterfly valve has flanges on it, with the flanges at both ends of the valve being secured to the pipe flanges using bolts. The relationship between the opening degree of a butterfly valve and the flow rate is essentially linear. If used for flow control, its flow characteristics are also closely related to the flow resistance of the piping. For example, if two pipes have identical valve sizes and types, but different pipe loss coefficients, the flow rates through the valves will differ significantly. ? If the valve is in a state with a large throttling range, cavitation can occur on the back side of the valve disc, which may lead to damage to the valve; it is generally used at angles other than 15°. ? When the butterfly valve is at a medium opening position, the shape of the opening formed between the valve body and the front end of the butterfly plate is centered around the valve shaft, with different conditions emerging on each side. The front end of the butterfly plate on one side moves in the direction of water flow, while it moves against the direction of water flow on the other side. As a result, one side forms an opening similar to a nozzle, while the other side forms an opening similar to a throttle orifice. The flow velocity is much higher on the nozzle side than on the throttle side, and negative pressure is generated below the valve on the throttle side, which often leads to the detachment of the rubber seals. ? The operating torque of a butterfly valve varies depending on the degree of opening and the direction in which the valve is opened or closed. For horizontal butterfly valves, especially those with large diameters, the torque generated by the difference in water pressure above and below the valve shaft due to the depth of water cannot be ignored either. Additionally, when a elbow is installed on the inlet side of the valve, flow deviation occurs, resulting in an increase in torque. When the valve is at an intermediate opening, the operating mechanism needs to self-lock due to the hydrodynamic torque. :P

Actually, I think to understand how a valve works, one needs to know several things: 1. You need to be familiar with this type of valve; 2. You need to know its advantages and disadvantages; 3. You need to understand its structural layout. It’s a good idea to take a closer look at pictures of the valve as well as its various components. Sometimes written information isn’t enough to help people remember things, and over time they may forget them. So it’s better to learn about it by observing the actual device, to get to know it and experience it firsthand – that way you’ll remember it! I’m not sure if what I said is correct; please forgive any shortcomings! You can also ask me questions!:lol :lol :lol QQ:928976489

A globe valve is a type of valve in which the closing element (valve disc) moves along the center line of the valve seat. The axis of its valve stem is perpendicular to the sealing surface of the valve seat. Due to the relatively short opening and closing stroke of the valve stem in this type of valve, as well as its highly reliable shut-off function, and because the change in the valve seat orifice is proportional to the stroke of the valve disc, it is highly suitable for regulating flow rate. Therefore, this type of valve is very suitable for use in cutting off or regulating flow, as well as for throttling. Globe valves have the following advantages: ① During opening and closing, the frictional force between the valve disc and the sealing surface of the valve body is lower than that of gate valves, thus they are more wear-resistant. ②The opening height is generally only 1/4 of the valve seat passage, so it is much smaller than gate valves ； ③Usually, there is only one sealing surface on the valve body and the valve disc, which makes the manufacturing process simpler and facilitates maintenance. ④Since its filler is generally a mixture of asbestos and graphite, it has a high temperature resistance rating. Generally, globe valves are used for steam valves. However, globe valves also have some disadvantages: Disadvantages: ① Since the direction of flow of the medium through the valve changes, the minimum flow resistance of globe valves is also higher than that of most other types of valves ； ②Due to the long travel distance, its opening speed is slower than that of a ball valve

A butterfly valve is a type of valve that uses a disc-shaped valve element to rotate back and forth by about 90° in order to open, close, and regulate the flow of fluid. The disc of a butterfly valve is mounted in the diameter direction of the pipeline. Within the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around its axis by an angle ranging from 0° to 90°; when it reaches 90°, the valve is in its fully open position. Butterfly valves have a simple structure, are small in size and light in weight, consisting of only a few components. Moreover, it can be quickly opened and closed by just a 90° rotation, making operation simple; at the same time, this valve boasts excellent fluid control properties. When the butterfly valve is in its fully open position, the thickness of the butterfly disc is the only resistance to the flow of the medium through the valve body; as a result, the pressure drop across this valve is very small, giving it excellent flow control properties. Butterfly valves come in two types of sealing: elastic sealing and metal sealing. Elastic-sealing valves, where the sealing ring can be embedded in the valve body or attached around the butterfly disc. Valves with metal seals generally have a longer lifespan than those with elastic seals, but it is difficult to achieve a perfect seal. Metal seals can withstand higher operating temperatures, while elastic seals have the drawback of being limited by temperature. If a butterfly valve is to be used for flow control, the key is to select the correct size and type of valve. The structural principle of butterfly valves makes them particularly suitable for manufacturing large-diameter valves. Butterfly valves are widely used not only in general industries such as petroleum, gas, chemicals, and water treatment, but also in the cooling water systems of thermal power plants.

The commonly used butterfly valves are wafer-type butterfly valves and flanged butterfly valves. A wafer butterfly valve is connected between two pipe flanges using bolts, while a flanged butterfly valve has flanges on it, with the flanges at both ends of the valve being secured to the pipe flanges using bolts. Butterfly valves have the following advantages: ① Simple structure, small size, light weight, and low material consumption; they can be used in large-diameter valves ； ②Rapid opening and closing, low flow resistance ； ③It can be used in media containing suspended solid particles, and depending on the strength of the sealing surface, it can also be used for powdered and granular media. It can be used for two-way opening, closing, and adjustment in ventilation and dust removal pipelines, and is widely applied to gas pipes and water pipelines in metallurgy, light industry, power, and petrochemical systems. Butterfly valves also have some disadvantages: ① The flow regulation range is limited; when the valve is opened to 30%, the flow rate is already over 95%. ②Due to the structure of butterfly valves and the limitations of their sealing materials, they are not suitable for use in high-temperature and high-pressure pipeline systems. The normal operating temperature is below 300°C, and the pressure rating is below PN40. ③Its sealing performance is inferior to that of ball valves and globe valves, so it is used in applications where high sealing requirements are not necessary.

The explanations on the 2nd floor are very comprehensive! But I support the suggestion from the 5th floor~~~ Go and see the site more often, and look at the actual products! It will deepen your understanding of theory~ Engineering places more emphasis on application!