ASCO solenoid valve seal

In principle, ASCO solenoid valves can be divided into three categories: 1) Direct-acting solenoid valves: Principle: When electricity is applied, the electromagnetic coil generates an electromagnetic force that lifts the closing element away from the valve seat, thereby opening the valve; when the power is cut off, the electromagnetic force disappears and the spring presses the closing element back against the valve seat, closing the valve. Features: It can operate normally under vacuum, negative pressure, or zero pressure, but the diameter generally does not exceed 25 mm. 　　2) Step-type direct-acting solenoid valve: Principle: It operates based on a combination of direct-acting and pilot-operated mechanisms. When there is no pressure difference between the inlet and outlet, when electricity is applied, the magnetic force lifts the pilot valve and the main valve’s closing element upward one after another, thereby opening the valve. When the pressure difference between the inlet and outlet reaches the starting value, upon power being applied, the electromagnetic force acts on the pilot valve, causing the pressure in the lower chamber of the main valve to rise while the pressure in the upper chamber drops. This pressure difference then pushes the main valve upward. When power is disconnected, the pilot valve uses spring force or medium pressure to push the closing element downward, thereby closing the valve. Features: It can operate at zero pressure difference or in vacuum as well as under high pressure; however, it requires a higher power level and must be installed horizontally. 　　3) Pilot-operated solenoid valve: Principle: When powered, electromagnetic force opens the pilot hole, causing the pressure in the upper chamber to drop rapidly. This creates a pressure difference with lower pressure above and higher pressure below the closing element, and the fluid pressure pushes the closing element upward, thus opening the valve. When power is cut off, the spring force closes the pilot hole, and the inlet pressure enters through the bypass hole. This results in a pressure difference with lower pressure below and higher pressure above the closing element, and the fluid pressure pushes the closing element downward, closing the valve. ASCO solenoid valve *Structural principle I. Direct-acting solenoid valves There are two types: normally closed and normally open. The normally closed type remains in a closed state when power is disconnected. When current flows through the coil, an electromagnetic force is generated, which enables the moving core to overcome the spring force and attract the stationary core, thereby opening the valve and allowing the medium to pass through. When the coil loses power, the electromagnetic force disappears, and the moving core returns to its original position under the action of the spring force, closing the valve and preventing the medium from passing through. It has a simple structure and reliable operation, functioning properly under zero pressure difference and slight vacuum conditions. The normally open type is the exact opposite; the normally open type is precisely the contrary. For sizes smaller than φ6, the normally open type is exactly the opposite: a solenoid valve with a smaller flow diameter. ) II. Step-type direct-acting solenoid valve This valve combines a primary opening mechanism with a secondary opening mechanism; the main valve and the pilot valve work together to use electromagnetic force and pressure difference to directly open the main valve port. When the coil is energized, an electromagnetic force is generated that causes the moving core and the stationary core to attract each other, thereby opening the pilot valve port. The pilot valve port is located on the main valve port, and the moving core is connected to the main valve core. At this point, the pressure in the upper chamber of the main valve is released through the pilot valve port. Under the combined effect of the pressure difference and the electromagnetic force, the main valve core moves upward, allowing the medium to flow through the main valve. When the coil is de-energized, the electromagnetic force disappears; at this point, the moving core closes the pilot valve orifice under the effect of its own weight and the spring force. As a result, the medium enters the upper chamber of the main valve core through the balance hole, causing the pressure in that upper chamber to rise. Under the combined effect of the spring’s restoring force and this increased pressure, the main valve closes, and the flow of the medium is stopped. It has a reasonable structure, reliable operation, and works reliably even at zero pressure difference. Such as: ZQDF, ZS, 2W, etc. 　　III. Indirect pilot-operated solenoid valves This series of solenoid valves is composed of a pilot valve and a main spool connected to form a passage; the normally closed type remains in a closed state when not powered. When the coil is energized, the magnetic force generated causes the moving core and the stationary core to attract each other, opening the pilot valve port and allowing the medium to flow toward the outlet. At this point, the pressure in the upper chamber of the main valve core decreases, falling below the pressure on the inlet side; this pressure difference overcomes the resistance of the spring, causing the main valve core to move upward and thus opening the main valve port, allowing the medium to flow through. When the coil is de-energized, the magnetic force disappears, and the moving core returns to its original position under the action of the spring force, thereby closing the pilot port. At this point, fluid flows in through the balance hole, causing the pressure in the upper chamber of the main valve core to increase; under the influence of the spring force, the main valve core moves downward and closes the main valve port. The principle of normally open is exactly the opposite. Such as: SLA, DF (for diameters of 15 mm and above), ZCZ, etc. Selection criteria: 1. The solenoid valve is selected based on pipeline parameters: diameter specification (i.e., DN) and connection type. 1. The diameter (DN) is determined according to the inner diameter of the pipelines in place or the required flow rate. 　　2. For the interface type, flange interfaces should generally be chosen for DN50 and above, while for DN50 and below, the choice can be made according to the user’s requirements. 　　II. Selection of solenoid valves based on fluid parameters: material and temperature range. 1. For corrosive fluids: corrosion-resistant solenoid valves made of all stainless steel are suitable; for food-grade ultra-pure fluids, solenoid valves made of food-grade stainless steel are appropriate. 　　2. High-temperature fluids: It is necessary to choose solenoid valves made from high-temperature resistant electrical and sealing materials, and those with a piston-type structure should be selected. 　　3. Fluid state: It can be gaseous, liquid, or in a mixed state; in particular, when placing orders for pipes with a diameter larger than DN25, it is necessary to distinguish between these states. 　　4. Fluid viscosity: It can generally be chosen arbitrarily as long as it is below 50 cSt; if it exceeds this value, a high-viscosity solenoid valve should be used. 　　III. Selection of solenoid valves based on pressure parameters: principles and structural types 1. Nominal pressure: This parameter has the same meaning as that of other common valves; it is determined according to the nominal pressure of the pipeline. 　　2. Operating pressure: If the operating pressure is low, a direct-acting or step-by-step direct-acting principle must be used; when the minimum operating pressure difference is above 0.04 Mpa, direct-acting, step-by-step direct-acting, or pilot-operated types can all be selected. 　　IV. Electrical selection: For voltage specifications, AC220V and DC24 are preferred as they are more convenient. 　　V. Selection based on the duration of continuous operation: normally closed, normally open, or capable of remaining powered on. 1. When the solenoid valve needs to remain open for an extended period of time, with that time being longer than the time it is closed, a normally open type should be chosen. 　　2. If the operation time is short or the on and off periods are brief, choose the normally closed type. 　　3. However, for some applications related to safety protection, such as flame monitoring in furnaces and kilns, normally open types cannot be used; instead, types that can remain powered on for an extended period should be chosen. VI. Select auxiliary functions based on environmental requirements: explosion-proof, check valve, manual operation, fog resistance, water spray resistance, and submersion resistance.