How to select a valve? Valve selection criteria

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　　1. How to select a flanged gate valve A flanged gate valve is a gate valve that uses a flange as its connection method, and this is the most common type of connection. Flange gate valves are stable and reliable when used in pipelines, which is why they are commonly employed in high-pressure pipelines. 　　Application range of flanged gate valves: Flanged gate valves are widely used in industries such as petroleum, chemicals, and thermal power plants, as valve devices for connecting or shutting off fluids in oil, water, and steam pipelines. 　　For specific methods for selecting flanged gate valves, you can consult the technical staff at the Fujian Biaoguang Valves website! 2. Key points for selecting groove-type signal gate valves: These gate valves have a flat bottom design that is identical to that of the pipeline, which prevents the accumulation of debris and ensures smooth flow of fluids. They overcome issues such as rubber aging and rusting, and are used in automatic sprinkler fire protection systems. Let’s analyze how to select a grooved gate valve, as follows: 1. The flow characteristics of the control valve are chosen for the grooved gate valve based on the properties of the process medium. 　　2. Select the appropriate structural form and materials based on the process conditions. 　　3. Select the appropriate diameter of the control valve based on the process operating parameters. 　　4. Select the actuator appropriately. The response speed of the actuator should be sufficient to meet the process requirements; 5. For groove gate valves, the necessary auxiliary devices are selected based on the demands of the process. 　　6. Requirements of groove gate valves regarding control stroke time: The actuator selected for the gate valve must be capable of meeting both the requirements related to the valve’s stroke and those related to the leakage level specified by the process. In some cases, such as when using pressure control valves (including relief valves), it is necessary to take into account the actual possible pressure difference and apply an appropriate increase, which means that the actuator must be capable of generating a greater force. Otherwise, in the event of abnormalities in the process, the actual pressure difference before and after the control valve may be high, posing a risk that the valve cannot be closed or opened. 　　3. Key points for selecting soft-sealed butterfly valves? What are the consequences of improper selection? Damage caused by improper selection and poor operation of soft-sealed butterfly valves. This is mainly manifested by the failure to select valves according to the operating conditions; cut-off valves are used as throttle valves, resulting in an excessively high shut-off pressure, too rapid shutdown, or incomplete closure, which causes erosion and wear of the sealing surfaces. Erosion of the medium occurs as a result of the wear, scouring, and cavitation caused by the flow of the medium on the sealing surface. For specific recommendations on how to select soft-sealed butterfly valves, it is advisable to consult the more experienced technicians at Fujian Biaoguang Valve Network. 　　4. How to select an overhead eccentric hemispherical valve 　　1. General-purpose valves: Specification range DN40-1600. Suitable for applications with strict requirements such as sewage treatment, pulp production, and urban heating; 2. Special valves for the oil and chemical industry: sizes ranging from DN40 to 1600. Suitable for various types of oils such as crude oil and heavy oil, as well as for weakly corrosive two-phase mixed-flow media in the chemical industry; 3. Special valves for gas: sizes ranging from DN40 to 1600. Suitable for the control of gas transmission, including coal gas, natural gas, and liquefied gas; 4. Special valves for slurries: sizes DN40-1600. Suitable for industrial pipeline transportation in situations involving two-phase flow of liquid and solid substances, or chemical reactions that result in crystal formation or scaling during liquid transport; 5. Special valves for coal ash: sizes ranging from DN40 to 1600. Suitable for control in power plants, hydraulic slag removal systems, or gas transmission pipelines. 　　7. It has a wide range of applications; the diameter can range from a few millimeters to several meters, and it can be used in conditions ranging from high vacuum to high pressure. 　　8. Due to the wiping action of ball valves during opening and closing, they can be used in media containing suspended solid particles. 　　5. How to select a double-eccentric hemispherical valve Application areas of double-eccentric hemispherical valves: 1. General-purpose valves: They feature a rational design and a compact structure, offer low flow resistance and good sealing performance, as well as easy and flexible operation. They are particularly suitable for low-pressure piping systems handling media such as water, sewage, steam, and pulp. They can be equipped with electric or pneumatic controls, enabling remote automated operation. (Non-corrosive media such as water, steam, sewage, pulp, slurry, etc.). 　　2. Dedicated for coal powder injection: An ideal device for controlling the transportation of solids such as coal powder in dusty gases and particle fluids; it is widely used in various pipeline controls in metallurgy, mineral processing, power generation, and other production processes, including coal powder injection in blast furnaces, powder production systems, and dust removal systems. It features a straight-through structure with unobstructed flow channels, preventing dust accumulation and blockages. The sealing surfaces are made of Co-Cr-W alloy and have undergone special heat treatment, giving the valve resistance to erosion and wear. Additionally, the valve’s eccentric spherical surface possesses automatic compensation capabilities; by using the adjustment bolts on the worm gear, it is possible to restore sealing performance even when the sealing surfaces are somewhat worn. (Dusty gases, particulate fluids) 3. Specialized for the petrochemical industry: Designed for use in environments with high pressure and high temperatures, where media that are flammable, explosive, or prone to corrosion due to weak acids and bases are present. It features good sealing properties, corrosion resistance, easy operation for opening and closing, and the ability to automatically remove scale from the valve surface. It is suitable for transporting crude oil, heavy oil, and other such media, as well as in processes such as petroleum cracking and food production. (Petroleum, natural gas, gas, water, etc.). 　　4. Designed specifically for blast furnace gas and gas applications: The sealing components are made of Cr–Mn–Si cemented carbide, which offers resistance to fire, explosion, and static electricity. These components can withstand temperatures up to 560°C, and their corrosion and wear resistance are more than 6 times that of stainless steel sealing components. They are particularly suitable for use in pipelines and pressure control stations for transporting gas, coke oven gas, water gas, liquefied gas, and natural gas. 　　6. How to select a backflow preventer 　　1. Application scope of backflow preventers: 　　Backflow preventers are check valves used in various piping systems to strictly prevent the backflow of fluid, thereby protecting the fluid or equipment downstream from contamination. It consists of two series-connected check valves and a transition section, providing tight sealing to ensure no backflow of the medium. 　　A pipe backflow preventer is a safety device used to prevent backflow contamination in domestic drinking water pipes, thereby ensuring the hygiene and safety of such water. 　　2. Structure of the backflow preventer: A safety-type backflow preventer is composed of a drain device placed between two check valves. The upper chamber of the drain is connected to the inlet end of the primary check valve using a high-pressure hose. A secondary check valve is mainly composed of a valve body, valve cover, valve disc, gasket, spring, etc. The drain valve is mainly composed of a valve body, valve cover, diaphragm, valve disc, sealing plate, valve core, valve seat, spring, etc. A standard backflow preventer consists of two check valves connected in series. 　　3. Working principle of the backflow preventer: When the seal of one of the check valves is damaged, the other check valve continues to provide a seal, preventing backflow. However, once the seals of both check valves are damaged at the same time, they lose their check function; their safety and reliability are relatively lower, and their working principle is quite simple. The backflow preventer includes a drain device in the middle, built on the basis of the standard type; this allows it to prevent backflow contamination even if the seals of both check valves are damaged at the same time. 　　For specific methods for selecting backflow preventers, you can consult the experts at Fujian Biaoguang Valve Network! 7. How to select electric two-way valves First, we need to consider what diameter the electric two-way valve required by the client has and what its purpose is! 1. If it is used for fan-coils, the sizes are mostly DN15 to DN25 – there are only a few such options, and they refer to switch-type units; 2. If it is to be used on fresh air handling units, it is usually a proportional control electric two-way valve with a diameter of DN25 or larger; moreover, it is necessary to consider whether the client requires a feedback signal – if so, then a valve equipped with an actuator that provides 0–10V or 4–20MA signals should be chosen. 　　8. How to select a telescopic filter The principles for selecting a filter are as follows: A filter is a small device used to remove small amounts of solid particles from liquids, thereby ensuring the proper operation of equipment. When fluid enters the filter cartridge equipped with a filter screen of specific specifications, impurities are trapped, while the clean filtrate is discharged from the filter’s outlet. When cleaning is required, simply remove the detachable filter cartridge, clean it, and then reinstall it. 　　1. Filter inlet and outlet diameter: In principle, the diameter of the filter’s inlet and outlet should not be smaller than that of the inlet of the pump it is designed to work with; it is generally the same as the diameter of the inlet pipe. 　　2. Nominal pressure selection: Determine the pressure rating of the filter based on the highest pressure that may occur in the filtration pipeline. 　　3. Selection of pore count: The choice of the filter’s pore count is primarily determined by the size of the impurities that need to be filtered out, in accordance with the requirements of the medium processing process. The particle sizes that can be intercepted by screens of various specifications are listed in the table “Screen Specifications”. 　　4. Filter material: The material of the filter is generally chosen to be the same as that of the process pipeline it is connected to; depending on the operating conditions, filters made of cast iron, carbon steel, low-alloy steel, or stainless steel can be considered. 　　5. Calculation of filter pressure loss: For water filters, under normal conditions of rated flow rate, the pressure loss is 0.52 to 1.2 kPa.