Solenoid valve selection 2

Selection of solenoid valve 2. Reliability: unreliability will damage the entire system! 1. Working life, this item is not included in the factory test items, but is a type test item. To ensure quality, choose brand-name products from regular manufacturers. 2. Working system: divided into three types: long-term working system, recurring short-time working system and short-time working system. Our company's conventional products are all long-term working systems, that is, the coils are allowed to be energized for a long time. For situations where the valve is open for a long time and only closed for a short time, a normally open solenoid valve should be used. When used in short-time working systems and large batches, special orders can be made to reduce power consumption. 3. Working frequency: When the action 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 my country’s professional standards for solenoid valves. To ensure quality, famous brand products from regular manufacturers should be selected. There are some occasions where the number of operations is not many, but the reliability requirements are very high, such as fire protection, emergency protection, etc., so we must not take it lightly. It is particularly important to use two in conjunction with double insurance. 2. Economy: Uneconomy is a waste of money, energy and even life. It is one of the criteria for selection, 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, maintenance and other accessories. More importantly, the cost of a solenoid valve in the entire automatic control system and even the production line is very small. If you are greedy for small gains and choose the wrong one, the damage caused will be huge. Six on-site working conditions requirements 1. Select the solenoid valve according to the pipeline parameters: diameter specification (i.e. DN), interface mode (connection method) 1. Determine the diameter (DN) size according to the on-site pipeline inner diameter size or flow requirements. 2. Interface mode. Generally, flange interface is selected for DN>65. For DN≤65, threaded or flange interface can be freely selected according to user needs. 2. Select the solenoid valve according to the type of medium: valve body material, sealing material, temperature group 1. Corrosive fluid: The valve body should be made of stainless steel or PTFE (polytetrafluoroethylene, commonly known as the king of plastics), and equipped with fluororubber or PTFE sealing materials. 2. Edible or ultra-clean fluids: The valve body material should be made of sanitary stainless steel and equipped with silicone rubber sealing material. 3. High-temperature fluid: Choose a solenoid valve made of high-temperature resistant electrical materials and sealing materials, and choose a piston-type principle structure. 4. Fluid state: it can range from gaseous, liquid or mixed state, especially when the diameter is greater than 25, it must be distinguished because it is related to the guide hole parameters. 5. Fluid viscosity: Usually it can be selected arbitrarily below 50cSt. If it exceeds this value, a high viscosity solenoid valve needs to be selected. 6. Fluid cleanliness: When the medium contains impurities, install a filter in front of the solenoid valve and choose other structures. 3. Select the solenoid valve according to the pressure level: Principle structure type 1. When the solenoid valve needs to be started for a long time, and the continuous opening time greatly exceeds the closing time, the normally open type should be selected. 2. If the on and off switch is frequent or the on time is short or the on and off times are about the same, choose the normally closed type. 3. However, for some working conditions used for safety protection, such as furnace flame monitoring, gas leakage alarms, and fire safety linkage systems, emergency cut-off solenoid valves should be selected instead of long-term energization types (long-term energization is only a relative concept). You cannot choose the normally open type. 4. Self-retaining solenoid valve (also known as: bistable) is a new technology, which is mainly used in situations where energy saving or low-voltage driving is required. 4. Power supply voltage selection: Try to give priority to the commonly used AC220V, DC24V is more convenient. 5. Select the control method according to the length of working time or special needs: normally closed, normally open, self-maintaining, emergency cut-off (manual reset) 1. Nominal pressure: This parameter has the same meaning as other general valves, it is It is determined based on the nominal pressure of the pipeline or 1.5 times the operating pressure. 2. Working pressure difference: refers to the value obtained by subtracting the pipeline pressure at the front end of the valve from the pipeline pressure at the rear end of the valve when the solenoid valve is in a closed or open state;when there is no pressure difference, low pressure difference, or vacuum, the direct-acting type must be used Or distributed direct-acting principle;when there is a certain pressure difference or above, various principle and structural forms can be used. 6. Select auxiliary functions according to environmental requirements: explosion-proof, non-return, manual, waterproof fog, water spray, diving 1. Flammable and explosive environments