Thread Content
Classification of solenoid valves: 1. They can be divided into three categories based on their operating principle. 1.1 Direct-acting solenoid valve: As shown in Figure 1, this type of solenoid valve relies entirely on the pulling or pushing force of the electromagnet to drive the valve plug (moving core), thereby opening or closing the valve port. Current products include DF2 series solenoids for small bore sizes (<5mm), DF-DY low-pressure solenoids, and the solenoid heads for various pilot solenoids, such as the electromagnet shown in Figure 2. This valve is generally used in pipelines with small diameters; its operation (opening/closing) time is short, usually less than 50 milliseconds. It is suitable for controlling the flow of gases (air, oil, water, liquid chemicals) or liquids, and it has a long service life, with over 1 million operations possible. It is particularly suitable for low-pressure media, and it operates reliably even at zero pressure. It is also well-suited for various gas shielded welding machines. The drawback of this type of solenoid valve is that it does not come in large diameters, typically less than 5 mm. For high-diameter solenoid valves (15–100 mm) used with low-pressure media such as gas or propane, the electromagnets are large and expensive. Our factory’s ZCM (GSF) model is a highly reliable two-way direct-acting low-pressure solenoid valve. Figure 1 shows the DF2 direct-acting solenoid valve; Figure 2 shows the DF1 pilot solenoid valve; Figure 3 shows the combined direct-acting/pilot solenoid valve. 1.2 Pilot type: Figure 2 depicts the DF1 pilot solenoid valve. Its operating principle involves a diaphragm-based pilot structure – when electricity is applied, the electromagnet attracts the moving core, thereby opening the pilot valve. With more discharge and less replenishment, the pressure in the valve’s upper chamber decreases. A pressure difference is created, the medium lifts the diaphragm, flows through the main valve opening, and the valve opens. After a power outage, the moving iron core closes the pilot valve port, causing the pressure in the upper chamber of the valve to increase. This pressure pushes the diaphragm downward, creating a static pressure difference that closes the main valve port. When encountering a pilot solenoid valve for the first time, pay attention to observing its structure. It generally consists of a pilot solenoid, an armature core, a diaphragm or piston, a valve body, and a valve cover. To find the pilot valve port, the inlet diameter is relatively small while the outlet diameter is larger; the electromagnet operates the pilot valve port to drive the diaphragm or piston, thereby opening or closing the valve. Pilot-operated solenoid valves are widely used in two-way, three-way, and multi-port solenoid valves. The medium conditions in the pipeline using a pilot solenoid valve must allow for flow and maintain pressure. The pilot solenoid valve can be used only under a pressure difference. The minimum operating pressure difference for solenoid valves with diaphragm or piston structures is 0.05 Mpa. Sliding rod solenoid valves require more than 0.2 Mpa. Pipelines with too low a pressure difference or no pressure cannot use any pilot solenoid valves. When selecting a pilot solenoid valve, its minimum operating pressure should be considered. Commercial pilot two-way solenoid valves generally cannot be used in vacuum systems. It cannot function properly at low vacuum. Our factory has vacuum solenoid valves powered by atmospheric pressure (1 bar). Solenoids are available for any passage. 1. 3 Pilot direct-acting composite type: Figure 3 shows a solenoid valve with both pilot and direct lifting functions. When the medium pressure is high, a pilot valve is used to open and close the valve; when the medium pressure is low, an electromagnet directly lifts the valve plug to open and close the valve. This valve is used for high-frequency operation in environments where the pressure difference of the medium varies significantly, offering reliable performance ； It belongs to the high-end category of solenoid valves. Our factory’s TDF-DZY is a typical representative. The minimum operating pressure is 0 Mpa. 2. Classification by purpose: Solenoid valves are denoted by … on… off… according to their purpose. The digit represents the number of pathways, while the bit indicates the operating state of the valve, which can be open, closed, or in an intermediate state. 2.1 Two-position two-way solenoid valve: The solenoid valve has two states – open and closed. Two openings, one for exit and one for entry. This valve comes in two types: normally closed (the solenoid valve opens when powered) and normally open (the solenoid valve closes when powered). It is generally used in straight pipelines for fluids to control their flow on and off. 2.2 Two-position three-way solenoid valve: The solenoid valve has two states – open and closed. Three openings ； One outlet (working port A), one inlet P, and one exhaust port O. Used to control single-direction acting cylinders or hydraulic cylinders. Two three-way selector valves ； It has one inlet and two operating ports: one normally open and one normally closed. When powered, the normally open port closes while the normally closed port opens. 2.3 Two-position five-way solenoid valve (two-position four-way solenoid valve): The solenoid valve has two operating states – open and closed – one air inlet, two working ports, and two exhaust ports. Used to control bidirectional acting cylinders or hydraulic cylinders. 2.4 Three-position five-way solenoid valve: The solenoid valve has three states: open, closed, and intermediate. Five pathways. Cylinders or pistons with an intermediate position are used to control bidirectional motion. This type of solenoid valve is equipped with two solenoid coils. 3. Classification by medium used ； Solenoid valves are used with clean gases or liquids as the working medium. None of the solenoid valves are suitable for dusts or solids with poor fluidity. The flowing medium must not contain solid particles. 3.1 Medium: In the product model, T stands for compressed air, Z for steam, S for water, M for gas, F for refrigerant, A for ammonia, and Y for oil. These are the media that the solenoid valve passes through or controls. 3.2 Solenoid valves that are operated by compressed air as power are called pneumatic valves. Those operated by oil or water as power are called hydraulic valves. Those operated by turbine oil are called turbine valves. 3.3 Temperature: Classified by medium temperature into normal temperature type of 5–55°C. High-temperature type: 5–185°C. Low-temperature type: below 5°C. For solenoid valves using polytetrafluoroethylene as the sealing material, the maximum temperature of the medium must not exceed 185°C. Fluororubber seals can withstand temperatures of up to 300°C. For low-temperature solenoid valves, fluoroplastic seals are generally not used. Its static pressure sealing performance is poor. 3.4 Corrosive media: It is advisable to use solenoid valves made of fluoroplastic, as the medium should not come into contact with metal. Especially dilute acids. 4. Classification by usage environment: 4.1 Region: Users should classify it according to arid tropics, humid tropics, temperate zones, and frigid zones. Select the solenoid valve. 4.2 Ambient temperature: The temperature of the environment in which it is used. Terms such as high-temperature solenoid valves and low-temperature solenoid valves generally refer to the environment in question. 4.3 Enclosure protection rating: Dustproof and splash-proof products (their ratings are indicated by I and P), as well as mold-resistant. Environmental explosion protection: 1-pole 4T explosion-proof products for mines and shafts. Solenoid valves marked 2 pole 4T for use in factories. 5. Classification by operating pressure (medium): 5.1 Low-pressure solenoid valves: Medium pressure of 0–0.1 Mpa. For low-pressure solenoid valves, such as our factory’s DF2 and ZCM solenoid valves. 5.2 Conventional solenoid valves: Medium pressure range of 0.05–1 Mpa; they are mostly of the pilot-operated type. The pressure cannot be reduced to zero; there must be a minimum value. Such as ZCT (DF1), ZCS for water use, DTF steam solenoid valves. 5.3 Low and medium pressure solenoid valves: Medium pressure range of 0–1.6 (2) Mpa. Pilot plus direct lift structure. Model TDF-DZY. 5.4 High-pressure solenoid valve: A solenoid valve used at pressures above 2 Mpa. 6. The preferred power supplies are AC220V and DC24V. These two types of power supplies are commonly used by manufacturers of solenoid valves. The power supply for pulse solenoid valves must be a DC pulse power supply, with DC5/12/24V being the preferred options; the pulse width should be between 50-100 milliseconds