First, the selection of solenoid valve common sense <Applicability> <Reliability> <Security> <Economics> Second, the structural principle of the solenoid valve <Directive> <Step-by-step> <Indirect Pilot>
Applicability â— The fluid in the pipeline must be the same as the medium calibrated in the selected solenoid valve series.
â— The temperature of the fluid must be less than the calibration temperature of the solenoid valve selected.
â— Solenoid valve allows liquid viscosity to be generally below 20 CST, greater than 20 CST should be noted.
â— Working pressure difference, when the maximum pressure difference of the pipeline is less than 0.04MPa, the direct-acting type such as 2W, ZQDF, series, etc. should be selected; when the minimum working pressure difference is greater than 0.04MPa, the pilot-operated (pressure differential) solenoid valve can be selected; The working pressure difference should be less than the maximum calibration pressure of the solenoid valve; generally the solenoid valve is working in one direction, so pay attention to whether there is a back pressure difference, if there is a check valve installed.
â— When the fluid cleanliness is not high, the filter should be installed in front of the solenoid valve. Generally, the solenoid valve requires good cleanliness for the medium.
â— Pay attention to the flow aperture and the diameter of the nozzle; the solenoid valve is generally only controlled by the two-position switch; if necessary, please install the bypass pipe for easy maintenance; when there is water hammer, customize the opening and closing time of the solenoid valve.
â— Pay attention to the influence of ambient temperature on the solenoid valve.
◠The power supply current and power consumption should be selected according to the output capacity. The power supply voltage is generally allowed to be ±10%. It must be noted that the VA value is higher when the AC starts.
Reliability â— Solenoid valves are divided into two types: normally closed and normally open. Generally, the normally closed type is used. The power is turned on and the power is turned off. However, when the opening time is long, the normally open type is selected.
â— Life test, the factory is generally a type test project. It is said that there is no professional standard for solenoid valves in the country, so it is prudent to use solenoid valve manufacturers.
â— When the action time is short, the frequency is generally high, and the direct motion type is generally selected. The large diameter is selected as the fast series.
Safety â— Generally, the solenoid valve is not waterproof. When the conditions are not allowed, please choose waterproof type. The factory can be customized.
â— The highest nominal pressure of the solenoid valve must exceed the maximum pressure in the pipeline, otherwise the service life will be shortened or other unexpected conditions will occur.
â— All stainless steel type should be used for corrosive liquid, and plastic king (SLF) solenoid valve should be used for strong corrosive fluid.
â— Explosive environments must use the corresponding explosion-proof products.
Economical â— There are many solenoid valves that can be used universally, but the most economical products should be selected on the basis of meeting the above three points.
Direct-acting solenoid valves are available in both normally closed and normally open versions. When the normally closed type is powered off, it is in a closed state. When the coil is energized, an electromagnetic force is generated, so that the moving iron core overcomes the spring force and opens the valve directly with the static iron core, and the medium is in a path; when the coil is de-energized, the electromagnetic force disappears, and the moving iron disappears. The core is reset under the action of the spring force, and the valve port is directly closed, and the medium is blocked. The structure is simple, the action is reliable, and it works normally under zero pressure difference and micro vacuum. The normally open type is just the opposite. For example, the solenoid valve is smaller than the φ6 flow path.
Step-by-step direct-acting solenoid valve The valve is connected in one opening and two-opening. The main valve and the pilot valve step by step to directly open the main valve port with electromagnetic force and pressure difference. When the coil is energized, an electromagnetic force is generated to cause the moving iron core and the static iron core to be sucked, the pilot valve port is opened and the pilot valve port is disposed on the main valve port, and the moving iron core is connected with the main valve core, and the main valve is connected at this time. The pressure of the chamber is unloaded through the pilot valve port, and the main spool is moved upwards under the action of the pressure difference and the electromagnetic force to open the main valve medium circulation. When the coil is de-energized, the electromagnetic force disappears. The power core closes the main valve under the action of self-weight and spring return and pressure, and the medium is interrupted. The structure is reasonable, the action is reliable, the work is reliable when the pressure is zero, and the work is reliable when the pressure is zero. Such as: ZQDF, 2W.
Indirect Pilot Solenoid Valve This series of solenoid valves is composed of a combination of a pilot valve and a main spool to form a passage; the normally closed type is closed when not energized. When the coil enters the power, the generated magnetic force causes the moving iron core and the static iron core to be sucked together, the pilot valve port is opened, and the medium flows to the outlet. At this time, the pressure in the upper chamber of the main spool is reduced, lower than the pressure on the inlet side, and the pressure difference is overcome. The spring resistance moves upwards to achieve the purpose of opening the main valve port and the medium is circulated. When the coil is de-energized, the magnetic force disappears and the moving iron core moves downward under the action of the spring force to close the main valve port. The normally open principle is just the opposite. Such as: DF (φ15 or more caliber), ZCZ, etc.