Four key points for selecting solenoid valves
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1: Applicability The fluid in the pipeline must be the same as the medium specified for the selected solenoid valve series model. The temperature of the fluid must be lower than the rated temperature of the solenoid valve used. Solenoid valves are suitable for liquids with a viscosity generally below 20 CST; if the viscosity is higher than 20 CST, this should be specified. For operating pressure differences, when the maximum pressure difference in the pipeline is less than 0.04 MPa, direct-acting and step-direct-acting types such as the ZS, 2W, ZQDF, ZCM series should be selected ； A pilot-type (differential pressure type) solenoid valve can be used when the minimum operating pressure difference is greater than 0.04 MPa ； The maximum operating pressure difference should be less than the maximum rated pressure of the solenoid valve ； Generally, solenoid valves operate in one direction only; therefore, it is necessary to pay attention to any reverse pressure difference, and a check valve should be installed if needed. When the fluid cleanliness is not high, a filter should be installed in front of the solenoid valve, as solenoid valves generally require the medium to have high cleanliness. Pay attention to the flow orifice diameter and the pipe connection diameter ； Solenoid valves are generally controlled in only two positions: on and off ； If conditions permit, install a bypass pipe to facilitate maintenance ； When water hammer occurs, it is necessary to customize the adjustment of the solenoid valve’s opening and closing time. Pay attention to the effect of ambient temperature on solenoid valves. The supply current and power consumption should be selected based on the output capacity; the supply voltage generally allows a variation of around ±10%. It is important to note that the VA value is relatively high during AC startup. II. Reliability: Solenoid valves are divided into normally closed and normally open types ； Normally, a normally closed type is chosen; it opens when powered and closes when power is cut off ； But when the on time is long and the off time is short, a normally open type should be chosen. Life testing is generally considered part of the type testing procedures in factories. To be precise, there are no specific standards for solenoid valves in our country; therefore, care should be taken when selecting a manufacturer of solenoid valves. When the actuation time is short and the frequency is high, a direct-acting type is generally chosen; for large diameters, the fast series is used. III. Safety: Ordinary solenoid valves are not waterproof; in situations where water resistance is required, please choose a waterproof version, which can be custom-made by the factory. The maximum rated pressure of the solenoid valve must exceed the highest pressure in the pipeline; otherwise, its service life will be reduced or other problems may occur. For corrosive liquids, a fully stainless-steel model should be chosen; for highly corrosive fluids, a SLF solenoid valve is recommended. Appropriate explosion-proof products must be used in explosive environments. IV. Cost-effectiveness: Many solenoid valves can be used interchangeably, but the most cost-effective option should be chosen provided that it meets the above three requirements.
I have the same content here; I’ll send it to the original poster as a supplement. The four key performance aspects of solenoid valves are of great importance. 1. Safety: 1. Corrosive media: It is advisable to use plastic-based solenoid valves or those made entirely of stainless steel ； For highly corrosive media, an isolated diaphragm type must be used. Example CD-F. Z3CF. In neutral media, solenoid valves with copper alloy as the valve body material are also a good choice; otherwise, rust particles often fall off from the valve body, especially in situations where the valve is not used frequently. Copper materials cannot be used for ammonia valves. 2. Explosive environments: Products with the appropriate explosion-proof rating must be selected; waterproof and dust-proof models should be used for outdoor installations or in areas with high dust levels. 3. The nominal pressure of the solenoid valve should exceed the highest operating pressure in the pipeline. II. Applicability: 1. Medium properties: Different types of solenoid valves should be used for gaseous, liquid, or mixed states; for example, ZQDF is used for air, ZQDF—Y for liquids, and ZQDF—2 (or -3) for steam, otherwise misoperation may occur. The ZDF series of multi-functional solenoid valves can be used with both gas and liquids. It is best to specify the medium condition at the time of ordering, so that the installation user does not need to adjust it again. 1.2 Products of different specifications are required for different medium temperatures; otherwise, the coils will burn out and the seals will age, severely affecting their lifespan. 1.3 Medium viscosity, usually below 50 cSt. If this value is exceeded, and the passage diameter is greater than 15 mm, a ZDF series multi-functional solenoid valve must be ordered as a special order. Solenoid valves with a bore diameter of less than 15 mm for high viscosity fluids. 1.4 When the cleanliness of the medium is not high, a backflow filter valve should be installed in front of the solenoid valve; when the pressure is low, a direct-acting diaphragm solenoid valve such as CD—P can be used. 1.5 If the 1.5 medium flows in a directional manner and backflow is not allowed, ZDF—N and ZQDF—N require bidirectional flow only; special requests should be made in such cases. 1.6 The medium temperature should be within the range permitted by the solenoid valve. 2. Pipeline parameters 2.1 Select the valve port and model based on the requirements of the medium flow direction and the pipeline connection method. For example, when switching from one pipe to two pipes, choose CA5 and Z3F for small diameters; for medium or large diameters, select ZDF—Z1/2. For example, to control the convergence of two pipelines, select ZDF—Z2/1, etc. 2.2 The nominal diameter is selected based on the flow rate and the Kv value of the valve; it can also be chosen to match the inner diameter of the pipeline. Please note that some manufacturers do not indicate the Kv value; often, the size of the valve orifice is smaller than the diameter of the connection pipe. Do not settle for a lower price at the risk of causing problems. 2.3 Operating pressure difference: An indirect pilot type can be used provided that the minimum operating pressure difference is above 0.04 Mpa ； Those with a minimum operating pressure difference close to or less than zero must use direct-acting or step-direct-acting types. 3. Environmental Conditions 3.1 The maximum and minimum temperatures of the environment should fall within the allowable range; if these limits are exceeded, a special order must be placed. 3.2 In environments with high relative humidity or exposure to water droplets and rain, waterproof solenoid valves should be used. 3.3 In environments where there is frequent vibration, jolting, and impact, special types should be selected, such as marine solenoid valves. 3.4 In corrosive or explosive environments, priority should be given to selecting materials resistant to corrosion based on safety requirements. 3.5 If the environmental space is limited, choose a multi-functional solenoid valve, as it eliminates the need for a bypass and three manual valves and facilitates online maintenance. 4. Power supply conditions 4.1 AC and DC solenoid valves are selected accordingly based on the type of power supply. Generally, AC power is easy to obtain. 4.2 For voltage specifications, AC220V and DC24V should be given priority whenever possible. 4.3 For power supply voltage fluctuations, +%10% to -15% is typically allowed for AC, while for DC a range of around ±10% is acceptable; if these limits are exceeded, voltage stabilization measures must be taken or special ordering requirements should be specified. 4.4 The rated current and power consumption should be selected based on the power supply capacity. It should be noted that the VA value is high during start-up under communication conditions; indirect-acting solenoid valves should be given priority when capacity is insufficient. 5. Control precision: 5.1 Ordinary solenoid valves have only two positions – on and off. When high control precision and stable parameters are required, multi-position solenoid valves should be chosen ； The Z3CF three-position normally open solenoid valve offers three flow states: slightly open, fully open, and closed ； The ZDF—Z1/1 combined multi-functional solenoid valve offers four flow rates: full open, wide open, narrow open, and full open. 5.2 Action time: Refers to the time from when the electrical signal is applied or removed until the main valve completes its action. Only our company’s patented multi-functional solenoid valves allow for separate adjustment of the opening and closing times, which not only meets the requirements for control precision but also prevents damage caused by water hammer. 5.3 The leakage values indicated on the leakage volume samples represent the standard economic grade; if these values seem too high, please place a special order. III. Reliability: 1. Service life – this is not included in the factory testing procedures; it falls under the category of type testing. To ensure quality, brand-name products from reputable manufacturers should be chosen. 2. Working system: There are three types, namely long-term working system, repeated short-term working system, and short-term working system. In cases where the valve remains open for a long time with only short periods of closure, an normally open solenoid valve is advisable. When used in a short working schedule with large batch sizes, it can be ordered specially to reduce power consumption. 3. Operating frequency: When a high frequency of operation is required, a direct-acting solenoid valve is the preferred choice for the structure, and alternating current is the preferred power supply. 4. Action reliability: Strictly speaking, this test has not yet been officially included in China’s professional standards for solenoid valves; to ensure quality, it is necessary to choose branded products from reputable manufacturers. In some situations, the number of actions required is not high, but the demand for reliability is extremely high, such as in fire fighting and emergency protection – these areas must not be taken lightly. It is particularly important to also adopt a double safeguard by using two together. IV. Cost-effectiveness: Being uneconomical means a waste of funds, effort, and even lives; this is one of the criteria used for selection, but it must be done on the basis of safety, suitability, and reliability. Cost-effectiveness is not merely related to the price of the product; functionality and quality also need to be taken into account, as do the costs associated with installation, maintenance, and other accessories. More importantly, the cost of an electromagnetic valve within an entire automated control system or even within a production line is minimal. Choosing a substandard option in pursuit of lower costs can lead to significant damages. In short, cost-effectiveness refers not only to the price of a product, but also to its performance-to-price ratio as well as its overall cost-to-price ratio.