【Daily Question 20090403】Regarding the applications of solenoid valves?

Classification of solenoid valves: Based on the voltage level used, DC24V and AC220V are the most commonly applied. Based on the number of control channels and positions, two-position three-way and two-position five-way solenoid valves are the most widely used. Based on whether it has a pilot function, it is divided into direct-acting and pilot-type types, with the pilot-type being more commonly used. Application areas: In petrochemical systems, it is mainly used for controlling the pneumatic circuits of pilot-operated switch valves. There are also a few direct-acting solenoid valves that are used directly to control the medium, but their diameter is not large. Single electronic control refers to a solenoid valve with one electromagnet ； Dual control refers to solenoid valves with two electromagnets. Single-electrocontrol solenoids generally need to remain powered on for an extended period, while dual-electrocontrol solenoids do not. The solenoids on pneumatic switch valves used for interlock protection generally follow the principle of fail-safe design: the solenoid remains energized under normal conditions, and it loses power when the interlock conditions are met and the valve needs to be actuated.

It’s been mentioned upstairs already: lol. One more thing to add is that chain protection systems usually activate in the event of a power loss or air loss

1: Solenoid valves commonly used for sequential control generally come in 2/3-way, 2/4-way, and 2/5-way types; the power supply options include 24VDC and 220VAC, and they can be of direct-acting or pilot-operated types. There are also a small number of direct-acting solenoid valves that are used directly to control the medium. 2: Single electronic control: A single coil can be in either an excited or unexcited state, that is, charged or uncharged. Dual control: two coils, one to open the solenoid valve and the other to close it; under normal conditions, neither of them is energized. 3: In interlock design, it is generally fail-safe, meaning that under normal conditions the solenoid valve is energized.

Can the solenoid valve be adjusted continuously, or can it only be adjusted in two positions?

Force-combined solenoid valve: Solenoid valves can be used not only in pneumatic systems but also in hydraulic and hydrostatic systems, where they serve similar purposes. For example, low-power solenoid directional valves that do not require lubrication; the seals do not need oil, and the gases emitted do not contaminate the environment, making them suitable for use in industries such as food processing, pharmaceuticals, and electronics. With continuous technological advancements, solenoid valve technology, combined with control technology, computer technology, and electronic technology, is now capable of performing a variety of complex controls. For example, solenoid valves can be used in the field of intelligent control, as well as in wireless control technologies and similar applications. The solenoid valve can be controlled using electromagnetism, which enables it to integrate well with various electronic systems; this is one of the main reasons for its widespread use. Solenoid valves are widely used in various fields of production. With the advancement of electromagnetic control technology and manufacturing processes, solenoid valves can achieve more precise control, enabling them to function effectively in different pneumatic and hydraulic systems. Solenoid valve – Used in conjunction with solenoid valves. Two-position three-way solenoid valves are typically used together with single-acting pneumatic actuators. The \"two positions\" refer to the ability to control the valve in two states: on/off. The \"three-way\" aspect means that there are three channels for air flow; generally, one of these channels is connected to the air supply, while the other two channels are connected—one to the air inlet of the actuator and the other to its air outlet. For more details on how it works, refer to the schematic diagram of a single-acting pneumatic actuator. Two-position five-way solenoid valves are typically used in conjunction with double-acting pneumatic actuators. The two-position aspect means that there are two controllable states: open and closed. The five-way design features five channels for air flow; one of these channels is connected to the air supply, two are connected to the inlet and outlet ports of the external air chamber of the double-acting cylinder, and two are connected to the inlet and outlet ports of the internal air chamber. For more details on how they work, refer to the operating principle of double-acting pneumatic actuators. In terms of the gas path (or liquid path), a 2/3-way solenoid valve has 1 inlet port (connected to the gas supply), 1 outlet port (providing gas to the target device), and 1 exhaust port (a silencer is usually installed there; it can be omitted if noise is not a concern). The two five-way solenoid valves have 1 air inlet port (connected to the air supply source), 1 air outlet port for forward operation and 1 air outlet port for reverse operation (providing air supply for forward and reverse operations to the target device respectively), 1 exhaust port for forward operation and 1 exhaust port for reverse operation (equipped with a silencer). For small automatic control devices, industrial rubber air hoses with a diameter of 8~12 mm are generally used for the air supply lines. From an electrical perspective, two-position three-way solenoid valves are generally single-electrode controlled (i.e., with a single coil), while two-position five-way solenoid valves are generally double-electrode controlled (i.e., with two coils). The coil voltage levels are generally DC24V, AC220V, etc. Two-way three-port solenoid valves are divided into two types: normally closed and normally open. A normally closed valve means that the air path is closed when the coil is not powered, while a normally open valve means that the air path is open when the coil is not powered. Operating principle of the normally closed two-position three-way solenoid valve: When power is supplied to the coil, the air path is opened; once the power to the coil is cut off, the air path is closed, which is equivalent to a \"momentary\" operation. Operating principle of the normally open two-position three-way single-electrovalve solenoid valve: When power is supplied to the coil, the air path is closed; once the power to the coil is cut off, the air path is opened. This is what is referred to as \"momentary operation\". Operation principle of the two five-way dual-electronic control solenoids: When power is supplied to the forward-action coil, the forward-action air path is connected (air flows out from the forward-action outlet). Even after the power to the forward-action coil is cut off, the forward-action air path remains connected, and this state will persist until power is supplied to the reverse-action coil. When power is supplied to the counteraction coil, the counteraction air circuit is activated (air flows out of the counteraction exhaust port). Even after the power to the counteraction coil is cut off, the counteraction air circuit remains active, and this state will persist until power is supplied to the positive action coil. This is equivalent to “self-locking”. Taking into account these characteristics of the two-position five-way dual-control solenoid valves, when designing the electromechanical control circuit or writing PLC programs, it is sufficient to allow the solenoid coil to operate for 1–2 seconds; this helps to prevent the solenoid coil from being damaged. Solenoid valves are used in hydraulic systems to enable the opening and closing of fluid pathways or to change the direction of fluid flow. They typically consist of a valve spool that can slide under the action of electromagnetic force; depending on the position of this spool, the flow path of the solenoid valve changes as well. There are several working positions for the valve core, and the solenoid valve is accordingly referred to as a solenoid valve with that number of positions. The number of connections on the valve body, that is, the number of passages in the solenoid valve, determines whether it is called a one-way, two-way, or multi-way solenoid valve. After the solenoid valve is installed, all connections should generally be in place; the so-called operating position refers to the position of the valve core. When the coil is not powered, the valve core is in position A; when the coil is powered, it is in position B. Depending on its position, the valve core either connects or blocks various interfaces. Two-position for a solenoid valve means that the valve element of the solenoid valve has two distinct operating positions (open, closed). Two-way and three-way solenoid valves refer to solenoid valves that have two or three port openings on their valve body ； For example, a two-position two-way solenoid valve has one inlet and one outlet (two channels, the most common type); a two-position three-way solenoid valve used to control liquids has one inlet and two outlets (one of the outlets is normally open while the other is normally closed) ； The pneumatic directional solenoid valve has one inlet, one outlet, and an exhaust port ； Hydraulic: one inlet, one outlet, and one return.

Solenoids, both domestic and international, can be classified into three main categories based on their principle: direct-acting type and pilot-operated type. Further, due to differences in valve disc structure, materials, and principles, they are divided into six subcategories: direct-acting diaphragm structure, step-type diaphragm structure, pilot diaphragm structure, direct-acting piston structure, step-direct-acting piston structure, and pilot piston structure. Direct-acting solenoid valve: Principle: When electric current 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 against the valve seat, causing the valve to close. Features: It can operate normally under vacuum, negative pressure, and zero pressure, but the diameter generally does not exceed 25 mm. Direct-acting solenoid valve: Principle: It operates on a combination of direct-acting and pilot-operated mechanisms; when there is no pressure difference between the inlet and outlet, upon power application, the electromagnetic 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 application, the electromagnetic force operates the pilot valve; as a result, the pressure in the lower chamber of the main valve rises while the pressure in the upper chamber drops, and this pressure difference is used to push the main valve upward ； During a power outage, 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, but it requires a higher power level and must be installed horizontally. Pilot-operated solenoid valve: Principle: When electric current is applied, electromagnetic force opens the pilot hole, causing the pressure in the upper chamber to drop rapidly. This creates a pressure difference with higher pressure below and lower pressure above the closing element; the fluid pressure then pushes the closing element upward, thereby opening the valve ； When power is lost, the spring force closes the pilot hole; the inlet pressure rapidly creates a pressure difference around the valve closing element, with lower pressure at the bottom and higher pressure at the top. The fluid pressure then pushes the closing element downward, thereby closing the valve. Features: High upper limit for fluid pressure range; can be installed in any position; requires customization but must meet the fluid pressure difference requirements

In terms of principle, solenoid valves are divided into three main categories: direct-acting, step-by-step direct-acting, and pilot-operated. Based on differences in valve disc structure and material as well as principle-related distinctions, they are further divided into six subcategories: direct-acting diaphragm structure, step-by-step diaphragm structure, pilot-operated diaphragm structure, direct-acting piston structure, step-by-step piston structure, and pilot-operated piston structure. Application areas include metallurgy, chemicals, buildings, landscaping, and daily life, etc. What is a single electronic control unit? What is dual control? Single-electric-control refers to a situation where one solenoid valve is controlled by just one electromagnet; this is what is meant by single-electric-control. Dual control refers to a solenoid valve that is controlled by two electromagnets; this is what is meant by dual control. The typical interlock design for solenoid valves is such that the solenoid loses power when the interlock is in normal operation

Classification of solenoid valves: Based on the voltage level used, DC24V and AC220V are the most commonly applied. Based on the number of control channels and positions, two-position three-way and two-position five-way solenoid valves are the most widely used. Based on whether it has a pilot function, it is divided into direct-acting and pilot-type types, with the pilot-type being more commonly used. Application areas: In petrochemical systems, it is mainly used for controlling the pneumatic circuits of pilot-operated switch valves. There are also a few direct-acting solenoid valves that are used directly to control the medium, but their diameter is not large. Single electronic control refers to a solenoid valve with one electromagnet ； Dual control refers to solenoid valves with two electromagnets. Single-electrocontrol solenoids generally need to remain powered on for an extended period, while dual-electrocontrol solenoids do not. The solenoids on pneumatic switch valves used for interlock protection generally follow the principle of fail-safe design: the solenoid remains energized under normal conditions, and it loses power when the interlock conditions are met and the valve needs to be actuated.

1. Solenoid valves are classified into DC solenoid valves and AC solenoid valves based on their driving power source； Based on the control method, there are single-electronic control and dual-electronic control ； Classified by structure, there are two-way straight connectors, two-way tee connectors, two-way five-way connectors, etc. Straight-through solenoid valves are mostly used in the control of industrial processes, while three-way and five-way solenoid valves are primarily used in hydraulic and pneumatic control systems. 2. A single-electronic control unit has only one control coil, while a dual-electronic control unit has two control coils. 3. The typical interlock design for solenoid valves is such that the solenoid is energized when the interlock is in normal operation, which is a consideration for safety.

In fact, I think solenoid valves generally have two main uses. If they are connected to the air circuit of a control valve, then they are definitely used for interlocking purposes; the other use is in programmable valves, where they enable the opening and closing of the valve.

Based on the internal structure of the solenoid valve, they can be classified into pilot-operated, direct-acting, composite, recoil-type, self-retaining, pulse-type, bistable, two-way types, etc

Moderator, just a side note. It’s not a competition here; why refuse to share it online? As long as the technical aspects are correct, that’s enough. It takes effort too to conduct a search. For those long posts upstairs, can they guarantee that they typed every single word by hand?