Solenoid valve selection knowledge and its structural principle

A: Applicability The fluid in the pipeline must be consistent with the medium calibrated in the selected solenoid valve series models. Fluid temperature must be less than the selected solenoid valve calibration temperature. Solenoid valve to allow liquid viscosity generally below 20CST, greater than 20CST should be noted. Working pressure, the maximum pressure pipe when less than 0.04MPa should be used, such as ZS, 2W, ZQDF, ZCM series, such as direct acting and step-by-step; minimum working pressure greater than 0.04MPa can be used when the pilot Differential) solenoid valve; maximum working pressure difference should be less than the maximum calibration solenoid valve pressure; general solenoid valve are one-way work, so pay attention to whether there is anti-pressure difference, if installed check valve. The fluid cleanliness is not high should be installed in front of the solenoid valve filter, the general requirements of the solenoid valve cleanliness is better. Pay attention to the flow aperture and take over the caliber; solenoid valve generally only two switches control; conditions permit installation of the bypass pipe, easy maintenance; water hammer phenomenon to be customized when the solenoid valve opening and closing time adjustment. Note that the ambient temperature on the solenoid valve power supply current and power consumption should be selected according to the output capacity, the power supply voltage is generally allowed ± 10%, we must pay attention to AC starting VA value is higher. Second, the reliability of the solenoid valve is divided into two types of normally closed and normally open; generally use the normally closed type, power open, power off; but a very long time to open a very short time to open the normally open type. Life test, the factory generally belongs to the type test project, to be exact, our country does not have the professional standard of the solenoid valve, so carefully choose the solenoid valve manufacturer. Action time is very short When the frequency is higher, select the direct-acting type, large-diameter selection of fast series. Third, the general safety of the solenoid valve is not waterproof, please do not allow the waterproof conditions, the factory can be customized. The highest nominal pressure solenoid valve nominal pressure must exceed the maximum pressure within the pipeline, otherwise the service life will be shortened or other unexpected situations. A corrosive liquid should be used in all stainless steel, corrosive fluids should use the plastic king (SLF) solenoid valve. Explosive environment must choose the appropriate explosion-proof products. Fourth, the economy There are many solenoid valve can be universal, but to meet the above three points should be based on the selection of the most economical products. Principle of the structure of a solenoid valve: Direct-acting solenoid valve are normally closed and normally open two. Normally closed when the power is turned off, when the coil is energized to produce electromagnetic force, so that the moving core overcomes the spring force with the static iron core pull directly open the valve, the medium was access; electromagnetic force disappeared when the coil power off, moving iron Under the action of the spring force, the core is reset and the valve port is closed directly. The medium can not be connected. Simple structure, reliable action, zero pressure and micro-vacuum work properly. Normally open type is the opposite. Such as less than φ6 flow path solenoid valve. (Figure 1 is a typical structure) Second, the step-by-step direct-acting solenoid valve The valve used to open the valve and the second valve in one, the main valve and pilot step-by-step electromagnetic force and pressure directly open the main valve port . When the coil is energized, the electromagnetic force is generated so that the moving iron core and the static iron core are closed, the pilot valve port is opened and the pilot valve port is arranged on the main valve port, and the moving iron core is connected with the main valve spool. At this time, Cavity pressure unloading through the pilot valve port, the pressure difference and the electromagnetic force at the same time under the action of the main spool upward movement, open the main valve medium circulation. When the coil power is lost when the electromagnetic force disappears, then move the core in the weight and spring force under the action of closing the pilot valve hole, then the medium in the balance hole into the main spool on the cavity, so that the pressure on the cavity, this time The main valve is closed by spring return and pressure and the medium is shut off. Reasonable structure, reliable action, work at zero pressure difference is also reliable. Such as: ZQDF, ZS, 2W and so on. (Figure II is a typical structure) Third, the indirect pilot solenoid valve The series of solenoid valve by the pilot valve and the main valve connected to form a combination of channels; normally closed when not powered, was turned off. When the coil is energized, the magnetic force generated so that the moving core and the static iron core pull, open the pilot valve port, medium flow to the outlet, then the pressure on the main spool to reduce the pressure on the inlet side of the formation of pressure to overcome the spring Resistance and then move up to achieve the purpose of opening the main valve port, medium circulation. When the coil is de-energized, the magnetic force disappears. The movable iron core is reset to close the pilot port under the action of the spring force. At this time, the medium flows in from the balance hole, the pressure in the upper cavity of the main valve increases and moves downward under the spring force, Close the main valve port. The principle of normally open is the opposite. Such as: SLA, DF (φ15 above caliber), ZCZ and so on. (Figure three is a typical structure)

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