DN15 ELECTRIC Control Valve
Overview
Regulating valve, also known as control valve, is a device that uses power operation to change fluid flow in a process system. The International Electrotechnical Commission (IEC) defines the regulating valve [called Control Valve abroad] as: "It includes a net component, an internal valve body component that changes the flow rate of the process fluid, and one or more actuators. connected. The actuator is used to respond to the signal sent by the control component. The regulating valve is composed of an actuator and a valve component. The actuator is the driving device of the regulating valve. It generates corresponding thrust according to the signal pressure, causing the push rod to move periodically, thereby driving the valve core of the regulating valve to move. The valve component is the regulating part of the regulating valve. It directly interacts with the medium through the displacement of the actuator push rod to change the throttling area of the regulating valve to achieve the purpose of regulation. Regulating valves are mainly divided into pneumatic regulating valves, electric regulating valves and hydraulic regulating valves according to their energy sources. The difference lies in the actuator they are equipped with. The pneumatic control valve uses compressed air as the power source and is equipped with a pneumatic actuator. The electric control valve uses electricity as the power source and is equipped with an electric actuator; the hydraulic control valve uses hydraulic pressure as the power source and is equipped with a hydraulic actuator. According to needs, the regulating valve can be equipped with a variety of accessories to make it more convenient to use and more complete in function. These accessories include valve positioners, handwheel mechanisms, electrical converters, etc.
Valve Body Form
Straight through valve body
The straight-through valve body has an S streamlined channel, with smooth inner walls and equal cross-sections. It has the characteristics of small pressure drop loss, large flow rate and smooth flow.
Angle valve body
The angle valve body is completely the same as the straight-through valve body except that its shape is right-angled. It has the characteristics of compact structure, simple flow path and low resistance. It is especially suitable for working conditions such as easy coking, easy clogging, and high viscosity.
Three-way valve body
The three-way valve body is divided into two types: converging and diverting. It is mainly used for proportional adjustment or bypass adjustment. It takes up little space and has low cost.
Z type valve body
The Z-shaped valve body is mainly suitable for high-pressure working conditions. It is made of integral forging and has good pressure resistance. The internal flow path is simple and is not prone to vortex, backflow and other phenomena. Reduce the possibility of flash evaporation and cavitation in high pressure differential conditions.
Valve Bonnet Form
Standard valve bonnet
The standard valve bonnet is a normal temperature upper valve cover. The material of the valve bonnet is exactly the same as that of the valve body, which plays the role of closing the valve body and actuator. Working temperature:-30°C-260°C
High temperature valve bonnet
The high-temperature valve bonnet is specially designed for high-temperature working conditions. The contact area between the valve bonnet and the surrounding air is increased through the heat sink to dissipate heat. It can effectively protect the packing and actuator. Working temperature: +230°C-530°C
Low temperature extendable valve bonnet
The low-temperature extension valve bonnet is suitable for media in low-temperature conditions (liquid oxygen, liquid nitrogen). This type of upper valve bonnet can effectively protect the packing and actuator. The standard material is 304 or 316. Materials with different expansion coefficients can also be used according to working conditions. Operating temperature:-196°C-45°C
Metal bellows sealing valve bonnet
The metal bellows sealing valve cover is equipped with a stainless steel bellows component to isolate the medium from the outside world and ensure that the valve stem moves up and down. In addition, a standard stuffing box is placed inside the upper valve cover to ensure that no waste, accidents or environmental pollution will be caused by leakage of the medium. Working temperature:-60°C-530°C
Selection Of Valve Body Materials
High temperature materials
As a high-temperature material, high-temperature strength, changes in metallographic structure at high temperatures, and corrosion resistance must be fully considered. It is generally required that alloy steel materials contain chromium, nickel, and molybdenum elements. In addition, at high temperatures and altitudes, steel is corroded by hydrogen, which generally causes decarburization and embrittlement. After metal elements such as chromium, nickel, and molybdenum are added to steel, it combines with carbon elements to improve the hydrogen corrosion resistance of steel.
Cryogenic materials
When selecting low-temperature materials, the low-temperature impact value of the material must be fully considered, as well as the brittleness problem of reduced toughness of the material at low temperatures. Therefore, materials used in low-temperature conditions must have sufficient toughness at low temperatures. The steel materials selected for valves at different temperatures must meet the impact energy specified by the standards at their applicable temperatures to be safe and reliable. Austenitic stainless steel has relatively stable low-temperature mechanical properties, so it is often used.
Cavitation resistant material
When the fluid is a liquid, especially when flash evaporation or cavitation occurs, the cavitation resistance of the material must be fully considered. Cavitation-resistant materials are mainly divided into two types: a. High hardness materials. (Heat treatment increases hardness); b. Materials with strong oxide layer, toughness and fatigue strength. (Surface heat treatment improves the surface hardness of the material); c. Partially hardened materials. (surfacing treatment);
Corrosion-resistant materials
The amount of corrosion of metal materials is generally divided into general corrosion, crevice corrosion, intergranular corrosion, hole corrosion, stress corrosion, etc. No material can withstand all types of corrosion. In fact, the corrosiveness of materials is also related to the type, concentration, and temperature of the fluid, as well as whether the fluid contains oxidants and flow rate, etc., which makes the selection of materials more complicated. Commonly used corrosion-resistant materials for control valves are mainly lining materials such as PTFE and F46, or special metals such as higher-cost austenitic stainless steel, 20# alloy steel, Hastelloy B, Hastelloy C, and titanium.
Valve Internal Component Materials
Main methods of hardening treatment
Commonly used valve internal component materials are SUS304, SUS316, SUS316L, SUS410, SUS420, etc., and are processed accordingly according to different fluid conditions. For controlling cavitation fluids, fluids containing solid particles, and high-temperature and high-pressure situations, they must be hardened. treatment to extend the service life of the valve.
Heat treatment
a.304/316 solid solution treatment This series of materials is austenitic stainless steel and is mainly used in working conditions where the medium is corrosive or in low-temperature situations. When the medium is highly corrosive, solution treatment must be carried out. The purpose of solution treatment is to improve the hardness and corrosion resistance of the material. Temperature range -196~530°C
b.410/420 quenching and tempering treatment (quenching + tempering) The material of this series is martensitic stainless steel, which is an excellent cavitation-resistant material. It must be quenched and tempered when used in high-temperature and high-pressure difference situations. The purpose of quenching and tempering treatment is to greatly improve the hardness of the material and extend its service life under harsh working conditions. Temperature range -45~425°C
c.17-4PH precipitation hardening treatment Different types and quantities of strengthening elements are added to the chemical composition of stainless steel, and different types and quantities of carbides, nitrides, carbides and intermetallic compounds are precipitated through the precipitation hardening process, which not only improves the strength of the steel but maintains sufficient toughness. A type of high-strength stainless steel, referred to as precipitation hardening. Temperature range -45~425°C
Surface hardening treatment
Surface heat treatment is divided into two categories: surface quenching and surface chemical heat treatment. a. Flame heating surface quenching, contact electric heating surface quenching, induction heating surface quenching, etc. b. Carburizing, nitriding, carbonitriding, chromium boronizing, copper infiltrating, etc.
Surfacing treatment
Stellite cladding (main components Co, Cr, W) is a commonly used hardening treatment method with excellent corrosion resistance. There are two methods of Stellite surfacing: full surfacing and partial surfacing. There is no standard regulation for the specific surfacing method. It usually depends on the different pressures and temperatures of the fluid and whether the fluid contains particles. The types of surfacing welding are as follows:
Selection Of Sealing Materials In The Valve
Introduction to balanced sealing ring
Spring-actuated PTFE seals are high-performance seals with a special spring inside a U-shaped PTFE. Appropriate spring force plus system flow pressure will push out the sealing surface and gently press the sealed surface to produce a very excellent sealing effect. The sealing surface is optimally short and thick, thereby reducing friction and extending service life.
Hot Tags: gas regulated control 100mm pressure relief valve, China, manufacturers, suppliers, factory, buy, price, quotation, 4 20ma Valve Actuator, Linear Electric Actuator For Rotork, Temperature Control Valve, Motor Operated Butterfly Valve, Proportional Valve For Water, Electric Rotary Valve Actuator
