Four principles to follow when selecting solenoid valves

Thread Content

Four principles to follow when selecting solenoid valves: When choosing a solenoid valve, one should adhere to four principles – safety, suitability, reliability, and cost-effectiveness – in that order. 1. Safety: Neglecting safety can lead to disasters! 1. Corrosive media: Plastic King solenoid valves and all-stainless steel materials are recommended. For highly corrosive media, an isolated diaphragm type must be used. Example CD-F. In neutral media, it is also advisable to use solenoid valves with copper alloy as the valve body material; 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; for outdoor installations or locations with high dust levels, waterproof and dust-proof models should be chosen. 3. The nominal pressure of the solenoid valve should exceed the highest operating pressure in the pipeline. II. Applicability: Not applicable means spending money on something useless, plus it causes extra trouble! 1 Medium properties 1.1 Different types of solenoid valves should be used for gases, liquids, or mixed states of the medium; for example, ZQDF-1 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 for both gases and liquids. It is best to specify the medium condition at the time of ordering, so that the user does not need to perform any adjustments during installation. 1.2 Different medium temperatures require the use of products of different grades; otherwise, the coil may burn out and the seals may age, severely affecting the product’s lifespan. 1.3 Medium viscosity, usually below 50 cSt. If this value is exceeded, with a passage diameter of more than 15 mm, it is available for the ZDF series of multi-functional solenoid valves as a special order. For ducts smaller than 15 mm, use solenoid valves with high-viscosity oil. 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 medium flows in a directional manner and backflow is not allowed, please use the ZDF-N and ZQDF-N one-way solenoid valves ； If two-way flow is required, please make a special request. 1.6 The medium temperature should be within the range permitted by the solenoid valve. 2 Pipeline Parameters 2.1 Select the valve diameter and model based on the flow direction requirements of the medium and the pipeline connection method. For example, when used to switch from one pipeline to two pipelines, select CA5 and Z3F for small diameters ； For medium or large diameters, please choose ZDF-Z1/2. For example, to control the convergence of two pipelines, choose ZDF-Z2/1, etc. 2.2 The nominal diameter is selected based on the flow rate and the Kv value of the valve; the inner diameter of the pipe can also be used as a choice. Please note that some manufacturers do not indicate the Kv value; in such cases, the valve orifice size is often 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: For a minimum operating pressure difference of 0.04 MPa or higher, an indirect pilot type can be used ； For those with a minimum operating pressure difference close to or less than zero, direct-acting or step-direct-acting types must be selected. The maximum operating pressure difference should be within the allowable range of the solenoid valve. 3 Environmental Conditions 3.1 The maximum and minimum temperatures of the environment should be within the allowable range; if they exceed this range, a special order must be submitted. 3.2 In situations with high relative humidity in the environment 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 When used in corrosive or explosive environments, it is preferable to select corrosion-resistant or explosion-proof solenoid valves based on safety requirements. 3.5 In environments with limited space, a multi-functional solenoid valve is recommended, 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 speaking, AC power is more convenient to obtain. 4.2 The voltage specifications should preferably be AC220V and DC24V. 4.3 Voltage fluctuations: for AC, a tolerance of +10% to -15% is generally allowed, while for DC, a tolerance 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; when capacity is insufficient, indirect pilot-operated solenoid valves should be preferred. 5 Control accuracy 5.1 Ordinary solenoid valves have only two positions: on and off. When high control precision and stable parameters are required, please choose multi-position solenoid valves ； The ZDF-Z1/1 combined multi-functional solenoid valve offers four flow rates: fully open, wide open, narrow open, and fully closed. 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 Leakage rate: The leakage rate values provided for the samples represent the standard economic grade; if these values seem too high, please place a special order. III. Reliability: Unreliability will damage the entire system! 1. Service life: This item is not included in the factory testing procedures; it falls under the category of type testing procedures. To ensure quality, brand-name products from reputable manufacturers should be chosen. 2. Working system: There are three types – long-term working system, repetitive working system, and short-term working system. All of our company’s standard products are designed for continuous operation, meaning that the coils can remain powered on for an extended period of time. For situations 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 short working hours 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 should be used as the power supply. 4. Operational reliability: Strictly speaking, this test has not yet been officially included in China’s professional standards for solenoid valves; to ensure quality, it is advisable to choose well-known products from leading domestic manufacturers. In such situations, the number of actions required is not large, but the demands on reliability are very high, as in cases of fire fighting and emergency protection; these matters must not be taken lightly. It is particularly important to also use two safeguards in combination. IV. Cost-effectiveness: Being uneconomical means wasting funds, effort, and even lives! It is one of the scales chosen, but it must be economical on the basis of safety, suitability, and reliability. Economics is not just about the price of a product; its functionality and quality, as well as the costs associated with installation, maintenance, and other accessories, should be given priority. More importantly, the cost of a solenoid valve in the entire automated control system and even in the production line is minimal; however, choosing the wrong one in an attempt to save money can result in significant losses. In short, cost-effectiveness refers not only to the product price, but also to the performance-to-price ratio and the overall cost-to-price ratio of the product.