The solenoid valve is composed of an electromagnetic coil and a magnetic core. It is a valve body containing one or several holes. When the coil is energized or disconnected, the movement of the magnetic core will cause fluid to pass through the body or be cut off to change the direction of the fluid. The electromagnetic parts of the solenoid valve are composed of fixed iron core, moving iron core, coil and other components; The valve body part is composed of spool, spool sleeve, spring base, etc. The solenoid is mounted directly to the body, which is enclosed in a sealed tube, creating a concise, compact package. We commonly used in the production of solenoid valves have two three-way, two four-way, two five-way and so on. Here to talk about the meaning of two: for the solenoid valve is live and lose power, for the control of the valve is open and close.The fault of the solenoid valve will directly affect the action of the switching valve and the regulating valve. The common fault is that the solenoid valve does not work, which should be investigated from the following aspects:1. The solenoid valve connector is loose or the wire falls off. The solenoid valve shall not be electric, and the wire can be fastened.2, solenoid valve coil burned out, can remove the solenoid valve wiring, with a multimeter measurement, if open, the solenoid valve coil burned out. The reason is that the coil is damp, causing bad insulation and magnetic leakage, resulting in excessive current in the coil and burned, so to prevent rain into the solenoid valve. In addition, the spring is too strong, the reaction force is too large, the coil turns too few, suction is not enough can also make the coil burned. In case of emergency, the manual button on the coil can be pressed from the "0" position to the "1" position to make the valve open.3, solenoid valve stuck: solenoid valve sleeve and spool with a small gap (less than 0.008mm), generally is a single piece assembly, when there are mechanical impurities into or too little oil, it is easy to get stuck. The treatment method can be steel wire from the head hole inserted, so that it springs back. The fundamental solution is to remove the solenoid valve, take out the spool and spool sleeve, clean with CCI4, so that the spool is flexible in the valve sleeve. When disassembling, attention should be paid to the assembly sequence and external wiring position of each component, so as to reassemble and wire correctly. It is also necessary to check whether the spray hole of the oil mist is blocked and whether the lubricating oil is enough.4. Air leakage: Air leakage will cause insufficient air pressure, which makes it difficult to open and close the forced valve. The reason is that the sealing gasket is damaged or the spool valve is worn and several cavities are channeling. When dealing with the solenoid valve failure of the switching system, the appropriate time should be selected to deal with the solenoid valve when it is out of power. If it cannot be handled within a switching gap, the switching system can be suspended and handled calmly.
1, the external leakage is blocked, the internal leakage is easy to control, the use of safetyInternal and external leakage is a hazard to safety. Other automatic valves usually extend the stem, by electric, pneumatic, hydraulic actuator control spool rotation or movement. It is necessary to solve the external leakage problem of long-term action valve stem dynamic seal; Only the solenoid valve is the electromagnetic force acting on the iron core sealed in the electric regulating valve magnetic separation sleeve, there is no dynamic seal, so the leakage is easy to block. Electric valve torque control is not easy, easy to produce internal leakage, or even pull the stem head; The structure of the solenoid valve allows easy control of internal leakage until it is reduced to zero. Therefore, the use of solenoid valve is particularly safe, especially suitable for corrosive, toxic or high and low temperature media.2, the system is simple, then the computer, low priceThe solenoid valve itself is simple in structure and low in price. It is easy to install and maintain compared with other kinds of actuators such as regulating valves. What is more remarkable is that the automatic control system is much simpler and the price is much lower. Because the solenoid valve is a switch signal control, and industrial control computer connection is very convenient. In today's computer popularity, the price of the era of substantial decline, the advantage of the solenoid valve is more obvious.3, action express, small power, lightweight appearanceSolenoid valve response time can be as short as a few milliseconds, even pilot solenoid valve can be controlled in dozens of milliseconds. Because of its own loop, it is more sensitive than other automatic valves. Properly designed solenoid valve coil power consumption is very low, energy saving products; Can also do only trigger action, automatically maintain the valve position, usually no power consumption. Solenoid valve size is small, saving space, lightweight and beautiful.4, the adjustment accuracy is limited, the applicable medium is limitedSolenoid valve usually only switch two states, the spool can only be in two limit position, can not be adjusted continuously, so the adjustment accuracy is also limited.Solenoid valve has higher requirements for media cleanliness, containing granular media can not be applied, such as impurities must be filtered first. In addition, viscous media cannot be applied, and the range of media viscosity suitable for specific products is relatively narrow.5, various models, a wide range of usesAlthough the solenoid valve has congenital shortcomings, the advantages are still very prominent, so it is designed into a variety of products to meet a variety of different needs, very wide range of uses. The progress of solenoid valve technology is also around how to overcome congenital deficiencies, how to better play the inherent advantages.
Solenoid valve is the electromagnetic coil energized magnetic force to attract to overcome the pressure of the spring to drive the spool action, on a solenoid coil, simple structure, cheap price, can only realize the switch;Electric valve is driven by a motor stem, drive the spool action, electric valve is divided into (off valve) and regulating valve. Turn-off valve is a two-position work that is fully open and fully closed, regulating valve is installed on the electric valve positioner, through closed-loop regulation to make the valve dynamic stability in a position.Electric valve and solenoid valve use comparisonSolenoid valve: Used for switching control of liquid and gas pipelines. It is a two-position DO control. Generally used for small pipe control.Electric valve: For liquid, gas and wind system pipeline medium flow analog volume regulation, AI control. In the control of large valves and wind systems can also use electric valves to do two switch control.Solenoid valve: can only be used as switching quantity, is DO control, can only be used for small pipe control, common in DN50 and below pipe.Electric valve: can have AI feedback signal, can be controlled by DO or AO, compared to large pipes and air valves.1. Switch form:Solenoid valve is driven by coil, can only be opened or closed, switch action time is short.The drive of the electric valve is generally driven by the motor. The opening or closing action needs a certain amount of time to complete the simulation. It can be adjusted.2. Job Nature:Solenoid valve general flow coefficient is very small, and the working pressure difference is very small. For example, the general flow coefficient of 25 caliber solenoid valve is much smaller than 15 caliber electric ball valve. Solenoid valve is driven by electromagnetic coil, relatively easy to be damaged by voltage impact. Equivalent to the role of the switch, is on and off 2 roles.The electric valve is generally driven by a motor, more resistant to voltage impact. Solenoid valve is fast opening and fast closing, generally used in small flow and small pressure, switching frequency is required to large place electric valve vice versa. The opening of the electric valve can be controlled, the state is open, closed, half open and half closed, you can control the flow of the pipeline medium and the solenoid valve can not meet this requirement.Solenoid valve general power can be reset, electric valve to such a function needs to add a reset device.3. Applicable technology:Solenoid valve is suitable for some special process requirements, such as leakage, fluid medium, etc., the price is more expensive.Electric valves are generally used for regulation, but also switch quantity, such as: fan coil end.
Solenoid valve sealing materials are currently three of the most commonly used.NBR rubberMade of butadiene and acrylonitrile by emulsion polymerization, nitrile rubber is mainly produced by low temperature emulsion polymerization, excellent oil resistance, high wear resistance, good heat resistance, strong adhesion. Its disadvantages are poor low temperature resistance, poor ozone resistance, poor electrical performance, slightly lower elasticity.In addition, it also has good water resistance, air tightness and excellent bonding properties. Widely used in making a variety of oil-resistant rubber products, a variety of oil-resistant gaskets, gaskets, sleeves, flexible packaging, soft rubber hose, printing and dyeing cots, cable rubber materials, etc., in the automobile, aviation, petroleum, copying and other industries become essential elastic materials.Nitrile butadiene rubber has excellent oil resistance, its oil resistance is second only to polysulfide rubber and fluorine rubber, and has wear resistance and air tightness. The disadvantage of butadiene rubber is that it is not resistant to ozone and aromatic, halogenated hydrocarbon, ketone and ester solvents, and is not suitable for insulation.Main useNitrile rubber is mainly used in the production of oil-resistant products, such as tubing, tape, rubber diaphragm and large oil capsule, often used in the production of all kinds of oil-resistant molding products, such as O-ring, oil seal, bowl, diaphragm, valve, bellows, and also used in the production of rubber plate and wear-resistant parts.EPDM ethylene propylene diene rubberEpdm is a terpolymer of ethylene, propylene and unconjugated diolefin, which began commercial production in 1963. Worldwide consumption is 800,000 tons per year. The most important characteristic of EPDM is its excellent oxidation resistance, ozone resistance and erosion resistance. Because EPDM belongs to polyolefin family, it has excellent vulcanization characteristics. Among all rubbers, EPDM has the lowest specific gravity. It can absorb a large amount of fillers and oils without affecting characteristics. So you can make cheap rubber compounds.Molecular structure and properties: EPDM is a terpolymer of ethylene, propylene and unconjugated diolefin. Diolefin has a special structure. Only one of the two bonds can copolymerize, and the unsaturated double bond is mainly used as the cross-chain. The other one is not going to be the main chain, it's just going to be the side chain. The main polymer chain of epDM is completely saturated. This property makes EPDM resistant to heat, light, oxygen and, above all, ozone. Ethylene propylene diene is essentially non-polar, resistant to polar solutions and chemicals, has low water absorption, and has good insulation properties.characteristic1. Low density and high filling;2, aging resistance;3, corrosion resistance;4, water steam resistance;5. Resistance to excessive hot water;6, electrical performance;7. Elasticity;8. Adhesion.VITON Fluorine Rubber (FKM)Rubber whose molecules contain fluorine are of various types according to fluorine content or monomer structure; Fluorinated rubber has better high temperature resistance than silicone rubber, chemical resistance, resistance to most oils and solvents (except ketones and esters), good weather resistance, ozone resistance, but poor cold resistance; Generally widely used in steam cars, B products, chemical plant seals, the use of temperature range -20℃ ~ 260℃, low temperature requirements when the use of low temperature resistance type can be used to -40℃, but the price is higher.
The solenoid valve does not work when energizedCheck whether the power cable is bad → Reconnect the power cable to the connectorCheck whether the power supply voltage is within the ± working range -→ normal position rangeWhether the coil is unwelded → reweldedCoil short circuit → Replace coilWhether the working pressure difference is inappropriate → adjust the pressure difference → or replace the appropriate solenoid valveThe fluid temperature is too high → replace the appropriate solenoid valveImpurities make the main valve core and moving core of the solenoid valve stuck to clean, if there is seal damage should be replaced and the filter should be installedThe liquid viscosity is too large, the frequency is too high and the life has to → replace the productThe solenoid valve cannot be closedThe seal of the main spool or iron moving core has been damaged → Replace the sealFluid temperature, viscosity is too high to replace the solenoid valveThere are impurities into the solenoid valve spool or moving core → cleanSpring life has reached or deformation → replacementThrottle hole balance hole blockage → timely cleaningThe working frequency is too high or the service life has reached → change the product or update the productOther circumstancesInternal leakage → Check whether the seal is damaged and the spring is improperly assembledExternal leakage → loose connection or broken seal → tighten screws or replace sealsNoise when energized → fasteners on the head loosen and tighten. Voltage fluctuation is not allowed within the range, adjust the voltage. Core suction surface impurities or uneven, timely cleaning or replacement.
1, installation should pay attention to the valve body on the arrow should be consistent with the medium flow direction. Do not install in a place where there is direct dripping or splashing. Solenoid valve should be installed vertically upward;2, the solenoid valve should ensure that the power supply voltage is 15%-10% of the rated voltage fluctuation range of normal work;3. After installation of the solenoid valve, there shall be no reverse pressure difference in the pipeline. And need to power up several times, so that the temperature can be formally put into use;4, the solenoid valve should be thoroughly cleaned before installation. The incoming medium shall be free of impurities. Valve before the filter;5. When the solenoid valve fails or is cleaned, in order to ensure the continued operation of the system, the bypass device should be installed.
Security:1, corrosive media: plastic king solenoid valve and stainless steel should be selected; The isolation diaphragm type must be used for the strong corrosive medium. Neutral medium, it is also appropriate to choose copper alloy for the valve shell material of the solenoid valve, otherwise, the valve shell often rust chips off, especially in the case of infrequent action. Ammonia valve can not use copper.2, explosive environment: must choose the corresponding explosion-proof grade products, open installation or dust occasions should choose waterproof, dust-proof varieties.3, the nominal pressure of the solenoid valve should exceed the highest working pressure in the tube.Applicability:1. Medium characteristics1) Quality gas, liquid or mixed state respectively choose different varieties of solenoid valve;2) Medium temperature products of different specifications, otherwise the coil will burn, seal aging, seriously affect the service life;3) Medium viscosity, usually below 50cSt. If more than this value, diameter greater than 15mm, with multifunctional solenoid valve; Diameter less than 15mm, with high viscosity solenoid valve.4) When the cleanliness of the medium is not high, the backwash filter valve should be installed in front of the solenoid valve. When the pressure is low, direct acting diaphragm type solenoid valve can be used;5) If the medium is directional flow, and does not allow backflow, need to use two-way flow;6) Medium temperature should be selected within the allowable range of the solenoid valve.2. Pipeline parameters1) Select the valve opening and model according to the medium flow direction requirements and pipeline connection mode;2) According to the flow rate and valve Kv value selected nominal diameter, also can choose the same pipe diameter;3) Working pressure difference: the lowest working pressure difference above 0.04Mpa can be used indirect pilot type; If the minimum working pressure difference is close to or less than zero, direct acting type or step by step direct type must be used.3. Environmental conditions1) The maximum and minimum temperature of the environment should be selected within the allowable range;2) In the environment of high relative humidity and water droplets rain, waterproof solenoid valve should be selected;3) In the environment often vibration, turbulence and impact occasions should choose special varieties, such as Marine solenoid valve;4) Use in corrosive or explosive environment should be preferentially selected according to safety requirements of corrosion resistant type;5) If the environmental space is limited, the multifunctional solenoid valve should be selected, because it eliminates the bypass and three manual valves and is convenient for online maintenance.4. Power supply conditions1) According to the type of power supply, choose AC and DC solenoid valves respectively. Generally speaking, AC power supply is convenient to access;2) AC220V.DC24V is preferred for voltage specification;3) Power supply voltage fluctuation usually AC selection +%10% -15%, DC allowed ±%10, if out of tolerance, must take voltage regulation measures;4) The rated current and power consumption should be selected according to the power supply capacity. It should be noted that the VA value is high when AC starting, and the indirect pilot solenoid valve should be preferred when the capacity is insufficient.5. Control accuracy1) The common solenoid valve only open, close two positions, in the control accuracy requirements and requirements of stable parameters need to choose more than one solenoid valve;2) Operation time: refers to the time when the electric signal is connected or cut off until the main valve is completed;3) Leakage: The leakage value given on the sample is the common economic grade.Reliability:1. Working life, which is not included in the ex-factory test item, belongs to the type test item. To ensure quality should choose regular manufacturers of famous brand products.2. Working system: Divided into long-term working system, repeated short-time working system and short-time working system. For a long time valve open only short time closed, it is appropriate to choose normally open solenoid valve.3. Working frequency: When the frequency of action is high, the structure should be preferred to direct acting solenoid valve, and the power supply should be preferred to AC.4. Operation reliabilityStrictly speaking, the test has not been formally included in the Chinese solenoid valve professional standards, in order to ensure the quality of the regular manufacturers should choose famous brand products. Some occasions are not much action, but the reliability requirements are very high, such as fire, emergency protection, must not be taken lightly. Especially important, should also take two use double insurance.Economy:It chooses one of the dimensions, but must be economical on the basis of safety, applicability and reliability.Economy is not only about the price of a product, but also about its function and quality, as well as the cost of installation, maintenance and other accessories.More importantly, a solenoid valve in the whole automatic control system in the whole automatic control system and even in the production line accounted for very little cost, if costed by small and cheap wrong selection and caused damage group is huge.
Solenoid valve selection should first follow the four original principles of safety, reliability, applicability and economy in turn, followed by the selection of six field conditions (namely pipeline parameters, fluid parameters, pressure parameters, electrical parameters, action mode and special requirements).Selection basis:1, according to the pipeline parameters, select the solenoid valve: diameter specification (namely DN), interface mode1) Determine the diameter (DN) size according to the internal diameter size or flow requirements of the field pipeline;2) Interface mode, generally >DN50 to choose flange interface, ≤DN50 can be free to choose according to user needs.2, according to the fluid parameters to select the solenoid valve: material, temperature group1) Corrosive fluids: corrosion-resistant solenoid valves and stainless steel should be selected; Food ultra-clean fluid: food grade stainless steel solenoid valve should be selected;2) High temperature fluid: to choose the use of high temperature electrical materials and sealing materials manufactured solenoid valve, but also to choose the type of piston structure;3) Fluid state: large to gaseous, liquid or mixed state, especially when the caliber is greater than DN25 must be distinguished;4) Fluid viscosity: usually below 50cSt can be arbitrarily selected, if more than this value, to choose high viscosity solenoid valve.3, according to the pressure parameters to select the solenoid valve: principle and structural varieties1) Nominal pressure: This parameter has the same meaning as other general valves, which is determined according to the nominal pressure of the pipeline;2) Working pressure: if the working pressure is low, direct action or step by step principle must be selected; When the minimum working pressure difference is above 0.04Mpa, direct acting type, step by step direct acting type, pilot type can be selected.4. Electrical selection: AC220V and DC24 should be preferred as far as possible for voltage specifications.5, according to the length of continuous working time to choose: normally closed, normally open, or sustainable power1) When the solenoid valve needs to be opened for a long time, and the duration of time is more than the closing time should be selected with normally open type;2) If the opening time is short or the opening and closing time is not much, then choose normally closed type;3) But some working conditions for safety protection, such as furnace and kiln flame monitoring, can not be selected normally open, should be selected for a long time power type.6, according to the environmental requirements to choose auxiliary functions: explosion-proof, check, manual, waterproof fog, water shower, diving.