There are many things that need attention in the selection of solenoid valves. What are the characteristics of solenoid valves that need to be paid attention to when selecting them?
1. Corrosive medium: plastic king solenoid valve and all stainless steel should be used; for strong corrosive medium, isolation diaphragm type must be selected. For neutral medium, it is also advisable to choose a solenoid valve with copper alloy as the valve housing material, otherwise, rust will often fall off in the valve housing, especially in occasions where the action is not frequent. Ammonia valves cannot use copper.
2. Explosive environment: products with corresponding explosion-proof grade must be selected, and waterproof and dust-proof varieties should be selected for outdoor installation or dusty places.
3. The nominal pressure of the solenoid valve should exceed the higher working pressure in the pipe.
1. Medium characteristics
1.1 Different types of solenoid valves are selected for gas, liquid or mixed states.
1.2 The medium temperature is different for products with different specifications, otherwise the coil will burn out and the seal will age, which will seriously affect the service life.
1.3 Medium viscosity, usually below 50cSt. If it exceeds this value, a multi-function solenoid valve with a diameter greater than 15mm is used for special order. Order a high viscosity solenoid valve with a diameter less than 15mm.
1.4 When the cleanliness of the medium is not high, a recoil filter valve should be installed in front of the solenoid valve. When the pressure is low, a direct-acting diaphragm solenoid valve can be used.
1.5 If the medium is directional, please make a special request.
1.6 The medium temperature should be selected within the allowable range of the solenoid valve.
2. Pipeline parameters
2.1 Select the valve port and model according to the requirements of the medium flow direction and the pipeline connection method.
2.2 Select the nominal diameter according to the flow rate and Kv value of the valve, and also choose the inner diameter of the pipe. Please note that some manufacturers do not mark the Kv value, and the size of the valve hole is often smaller than the diameter of the interface, so you must not covet the low price and cause trouble.
2.3 Working pressure difference
If the lower working pressure difference is above 0.04Mpa, you can choose the indirect pilot type, such as the sequential control SK pilot series solenoid valve; if the lower working pressure difference is close to or less than zero, you must choose the direct-acting or step-by-step direct type, such as the sequential control SK direct-acting series solenoid valves.
3. Environmental conditions
3.1 The higher and lower temperature of the environment should be selected within the allowable range, if there is a difference, a special order must be made.
3.2 In the environment where the relative humidity is high and there are water droplets and rain, the waterproof solenoid valve should be selected
3.3 In the environment where there is often vibration, turbulence and impact, special varieties should be selected, such as marine solenoid valves.
3.4 For use in corrosive or explosive environments, corrosion resistance should be selected first according to safety requirements
3.5 If the environmental space is limited, please choose a multi-function solenoid valve, because it saves the bypass and three manual valves and is convenient for online maintenance.
4. Power conditions
4.1 According to the type of power supply, select AC and DC solenoid valves respectively. Generally speaking, the AC power supply is easy to access.
4.2 The voltage specification is preferably AC220V.DC24V.
4.3 Power supply voltage fluctuation is usually +%10%.-15% for AC, and ±10% for DC. If it is out of tolerance, voltage stabilization measures must be taken or special order requirements must be put forward.
4.4 The rated current and power consumption should be selected according to the power supply capacity. It should be noted that the VA value is relatively high during AC starting, and the indirect pilot solenoid valve should be preferred when the capacity is insufficient.
5. Control precision
5.1 Ordinary solenoid valves only have two positions of on and off. When the control accuracy is high and the parameters are stable, please choose a multi-position solenoid valve.
5.2 Action time: refers to the time from when the electrical signal is turned on or off to when the main valve action is completed.
1. Working life, this item is not included in the factory test item, but belongs to the type test item. In order to ensure the quality, famous brand products from regular manufacturers should be selected.
2. Working system: long-term working system, repeated short-time working system and short-time working system. Conventional products are long-term working system, that is, the coil allows long-term energized work. For the situation that the valve is opened for a long time and only closed for a short time, a normally open solenoid valve should be selected.Used in short-time work system and batch
Larger sizes can be special ordered to reduce power consumption.
3. Working frequency: When the operating frequency is high, the structure should be a direct-acting solenoid valve, and the power supply should be AC.
4. Action reliability
Strictly speaking, this test has not been officially included in the professional standards of solenoid valves in my country. In order to ensure the quality, brand-name products from regular manufacturers should be selected. In some occasions, the number of actions is not many, but the reliability requirements are very high, such as fire protection, emergency protection, etc., and must not be taken lightly. Especially important, should also take two consecutive double insurance.
It is one of the selected scales, but it must be economical on the basis of safety, applicability and reliability.
Economy is not only the price of the product, but also its function and quality, as well as the cost of installation and maintenance and other accessories.
More importantly, the cost of a solenoid valve in the entire automatic control system is very small in the entire automatic control system and even in the production line.
Installation precautions are as follows:
1. When installing, pay attention that the arrow on the valve body should be consistent with the flow direction of the medium. Do not install in places where there is direct dripping or splashing of water. The solenoid valve should be installed vertically upward.
2. The solenoid valve should be guaranteed to work normally within the fluctuation range of 15%-10% of the rated voltage.
3. After the solenoid valve is installed, there must be no reverse pressure difference in the pipeline. And it needs to be energized several times to make it suitable for temperature before it can be officially put into use.
4. The pipeline should be thoroughly cleaned before the solenoid valve is installed. The incoming medium should be free of impurities. Install a filter before the valve.
5. When the solenoid valve fails or is cleaned, in order to ensure the continuous operation of the system, a bypass device should be installed.
Regarding the characteristics of the solenoid valve, which characteristics need to be paid attention to when selecting,The above characteristics are explained very clearly to everyone, hurry up and get up~