Tracing the history of the development of the solenoid valve, so far, the solenoid valve at home and abroad from the principle is divided into three categories (ie: direct acting, step-by-step pilot), and from the valve structure and material differences The difference between the principle is divided into six sub-categories (direct acting diaphragm structure, step-grate structure, leading diaphragm structure, direct acting piston structure, step-by-step piston structure, pilot piston structure). Direct-acting electromagnetic valve principle: When power is on, the electromagnetic coil generates electromagnetic force to lift the closing member from the valve seat, the valve opens; when the power is off, the electromagnetic force disappears, the spring presses the closing member against the valve seat, and the valve is closed. Features: In vacuum, negative pressure, zero pressure can work normally, but the path generally does not exceed 25mm. Distribution of direct-acting solenoid valve principle: It is a direct acting and pilot-based combination of principles, when the inlet and outlet without pressure, the power, the electromagnetic force directly to the pilot valve and the main valve closing member in turn lifted up, The valve is open. When the inlet and outlet to achieve the start of the pressure difference, the electricity, the solenoid pilot small valve, the main valve lower chamber pressure rises, the pressure on the chamber down, so that the use of pressure to push the main valve open; power, the pilot valve spring Force or media pressure to push the closure, move down, the valve closed. Features: At zero pressure or vacuum, high pressure can also be * action, but the power is larger, the requirement must be horizontal installation. Pilot solenoid valve principle: When power is on, the electromagnetic force opens the pilot hole and the pressure in the upper chamber rapidly drops, forming a low pressure differential on the lower part of the closing part. The fluid pressure pushes the closing part to move upward and the valve opens. The spring force closes the pilot hole and the inlet pressure rapidly passes through the bypass hole to create a low pressure differential across the valve. The fluid pressure forces the valve to move downward and close the valve. Features: High fluid pressure range high, can be installed (to be customized), but must meet the fluid pressure conditions. Solenoid valve installation and maintenance Before installation, carefully read the product manual, check the product meets the requirements, remember to install the points, be prepared. Proof nameplate parameters and parameters of the selected product parameters are the same, the supply voltage should meet the rated voltage and voltage fluctuations: AC + 10% ~ -15%, DC +10% ~ -10%, usually coil assembly should not be opened. Before taking over the pipeline with 0.3MPa pressure flushing, the pipeline of metal powder and sealing material residues, rust and other clean-up. Pay attention to the cleanliness of the media, if the media mixed with dirt, impurities, etc. to prevent the normal operation of the solenoid valve, the filter should be installed in the pipeline filter â‰¥ 60 mesh filter. Solenoid valve should not be installed in the pipe recess, installed in the discharge pipe of the container, be careful not from the bottom of the container leads, but should be installed in the container slightly above the position. If the media will start hammering, then use a solenoid valve with water hammer or take appropriate precautions. Steam valve inlet side should be equipped with steam traps, where the takeover should be tilted, the solenoid valve is generally oriented, can not be installed reverse, usually on the body with "â†’" to indicate the direction of medium flow, the installation in accordance with "â†’" The direction of the installation instructions, but the company may sometimes vacuum tubes or special circumstances there are proposals against the installation. Installation position: General Solenoid valve solenoid coil components should be upright, vertically mounted on the level of the pipeline in the ground, if space constraints or operating conditions must be sideways, such as building sewer pipe or upside down installation, please In the selection of orders made. Some products have special regulations, please follow the instructions to install. Take care when the seal material can not be used in excess. For threaded connections, the take-over thread should be held within the effective length and chamfered with a file at the half-pitch at the end, beginning at 2 teeth from the end to wind the seal tape, or an excessive amount of seal tape or adhesive will enter the solenoid Valve cavity, and the occurrence of an accident that hinder normal operation. Solenoid valve installation should have some space reserved for routine maintenance and regular maintenance. Installation with a wrench or pipe clamp to fix the valve body, and then screw on the take over, must not force the electromagnetic coil assembly on the deformation caused by the solenoid valve is difficult to work properly. Insufficient rigidity in the pipeline, or the phenomenon of water hammer, take over the valve before and after the stent is fixed. When used in a freezing place, the pipe shall be protected by heat insulating material or a heater shall be installed on the pipe. Check to see if there is any leak in the solenoid valve itself and its connection to the receiver. The connection of the coil leads to check, especially the case of three leads. Electrical components connected to the solenoid valve, such as relays, switches and contactors. Open the valve contact should not be vibration, otherwise the work will be unreliable, and affect the life of its solenoid valve. Electrical circuit to access the appropriate insurance line, as the electrical circuit protection.