The selection of common sense and the structure of the electromagnetic valve principle
A: applicability fluid pipeline must electromagnetic valve series models in the calibration and use of medium. The temperature of the fluid must be smaller than the calibration temperature of electromagnetic valve. Solenoid valve to allow the liquid viscosity, generally under 20 CST, more than 20 CST shall be indicated. Working pressure difference, line the high-pressure difference in less than 0. 04 mpa should be chosen as ZS, 2 w, ZQDF, ZCM series and type of moving step by step straight acting; The minimum working pressure difference is greater than zero. 04 mpa when guiding type (optional Differential pressure type) Electromagnetic valve; Maximum working pressure difference should be less than the biggest calibration pressure electromagnetic valve; General solenoid valve is a one-way work, so should pay attention to whether there is a pressure difference, if you have to install the check valve. Fluid cleanliness is not high when the filters should be installed in front of the electromagnetic valve, general cleanliness requirements for medium electromagnetic valve is better. Pay attention to the traffic pore size and diameter; Two general only switch electromagnetic valve control; Conditions permit, please install bypass pipe, easy maintenance; When there is water hammer to customize the electromagnetic valve opening and closing time to adjust. Pay attention to the environmental temperature on the influence of electromagnetic valve power supply current and power consumption should be selected according to the output capacity, power supply voltage generally allow & plusmn; About 10%, must pay attention to communication when starting the VA value is higher. Second, the reliability of electromagnetic valve normally open and normally closed; General selection normally closed type, electric open, power is shut down; But when opened for a long time closed in very short time to choose the normally open type. Life test, the factory generally belongs to the type testing project, specifically our country haven't professional standards of electromagnetic valve, so careful when choosing the electromagnetic valve manufacturer. Action time is very short at high frequency generally choose straight acting, large-caliber choose fast series. Three, security, general solenoid valve is not waterproof, when conditions are not allowed to use waterproof model, the factory can be customized. The highest calibration nominal pressure solenoid valve must be more than the highest pressure in the pipeline, otherwise life will shorten or other unexpected circumstances. Corrosive liquid should be chosen in all stainless steel type, appropriate chooses the corrosive fluid plastic king ( SLF) Electromagnetic valve. Explosive environment must choose corresponding explosion-proof products. Four, economy there are a lot of electromagnetic valve can be common, but are able to meet the above three points should be chosen on the basis of most economic products. The structure and principles of electromagnetic valve 1: direct acting solenoid valve is normally closed type and open type two kinds. Normally closed type power outages are closed, when the coil electricity to produce electromagnetic force, the moving core to overcome the spring force with the static iron core and open valve directly, medium is access; Disappear when the power coil electromagnetic force, under the action of spring force of moving iron core reset, close the valve directly, medium. Simple structure, reliable action, under the zero pressure difference and micro vacuum to work normally. Normally open type is just the opposite. If less than & phi; 6 the electromagnetic valve flow path. ( Figure 1 is a typical chart) Second, step-by-step direct acting solenoid valve is the valve is a valve and a second opening valve in an organic whole repeatedly, the main valve and guide step by step makes the electromagnetic valve and differential pressure directly open the main valve. When energized coil, thus moving iron core and static iron core and electromagnetic force, guide valve mouth open and guide valve port is located in the main valve port, and the moving core and the main valve core together, at this time the main valve cavity pressure unloading, through the pilot valve port under the action of pressure difference and the electromagnetic force at the same time the main valve core upward movement, open the main valve medium circulation. Disappear when the power coil electromagnetic force, the moving core under the action of gravity and spring force, close the valve guide hole, the medium in the balance hole core into the main valve cavity, the cavity pressure on rise, at this time in the spring return and pressure under the action of closing the main valve, medium. Reasonable structure, reliable operation, work is reliable when zero pressure difference. Such as: ZQDF, ZS, 2 w, etc. ( Figure 2 is a typical chart) Three, indirect guiding type electromagnetic valve the series electromagnetic valve formed by pilot valve and main valve core is linked to the channel combination; Normally closed type in an unpowered, is closed. When energized coil, the magnetic force made moving iron core and static iron core or absorption, pilot valve to open the mouth, medium of exports, the main valve core on the cavity pressure decrease, pressure is lower than the import side, the formation of differential pressure to overcome the spring resistance and then upward movement, achieve the purpose of opening main valve mouth, medium circulation. Disappear when coil electricity, magnetism, moving iron core under the action of spring force reduction and shut down the forerunner, the medium flow from balance hole, the main valve cavity pressure on the core, and under the action of spring force downward movement, close the main valve. Often open principle is just the opposite. Such as: the SLA, DF ( φ More than 15 diameter) , ZCZ, etc.