Precautions for using steam electric valves, as well as their advantages and disadvantages

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Advantages: In addition to its high reliability, full functionality, and ultra-lightweight design, electric control valves offer the following benefits: (1) They are convenient and cost-effective to use, as they eliminate the need for various expenses associated with setting up a gas supply station； ⑵By using the complex setup of \"pneumatic valve + electrical valve positioner + air supply\", it not only increases costs but also reduces reliability (the more components there are, the greater the factors that can lead to reduced reliability) ； ⑶From an economic perspective, in addition to avoiding the costs associated with gas supply stations, the cost of electrical valve positioners is also saved: a quality imported electrical valve positioner typically costs between 5,000 and 6,000 yuan, while higher-quality ones cost between 8,000 and 10,000 yuan; with this amount of money, it is possible to purchase the highly reliable electronic actuators mentioned above ； ⑷The number of steps has been reduced, which in turn reduces the amount of maintenance work required. Disadvantages: Steam electric valves also have their drawbacks: the heat generated by the motor’s operation can trigger thermal protection, causing the control valve to stop working ； Since the motor must go through multiple stages of reduction to generate torque, its operating speed is not very high; therefore it is not suitable for applications that require rapid opening and closing. Achieving both high torque and high speed remains a difficult challenge to overcome ； Due to the large number of moving parts, failures are relatively likely to occur. Especially in conditions where adjustments are made frequently, problems such as motor thermal protection, damage to reduction gears, and burnout of module thyristors can arise. In such situations, it is better to use pneumatic control valves. Precautions for using steam electric valves: For newly designed and installed control systems, to ensure that the control valves function properly during operation and to maintain the safe operation of the system, it is necessary to first check whether the markings on the valves match the design specifications before installing them. At the same time, the following items should also be debugged. Basic error limit ； Total journey deviation ； hysteresis ； dead zone ； Leakage amount (performed in applications with strict requirements). If a major overhaul is carried out on the control valve in the original system, in addition to verifying the items mentioned above, it is also necessary to check the sealing performance of areas such as the packing gland and connections of the old valve. In field use, many problems are not caused by the quality of the control valve itself, but rather by improper installation and use of it – factors such as an inappropriate installation environment, incorrect installation location or orientation, or unclean pipelines. Therefore, when installing and using electric control valves, the following points should be taken into account: (1) Control valves are field instruments, and the ambient temperature should be within the range of –25 to 60°C, with a relative humidity of ≤95%. If it is installed in an outdoor or high-temperature environment, waterproofing and cooling measures should be taken. In areas where there are sources of vibration, one should stay away from them or take additional vibration prevention measures. ⑵Control valves should generally be installed vertically; in special cases, they can be tilted. If the tilt angle is large or if the valve’s own weight is too great, support elements should be added to protect the valve. ⑶Pipelines equipped with control valves should generally not be placed too high above the ground or floor. When the pipeline height exceeds 2 meters, a platform should be provided as much as possible to facilitate the operation of the handwheel and ease maintenance. ⑷Before installing the control valve, the pipeline should be cleaned to remove dirt and slag. After installation, to ensure that no impurities remain inside the valve body, it is necessary to clean the valve again; that is, all valves should be opened when the medium is introduced, to prevent impurities from getting stuck. After using the handwheel mechanism, it should be returned to its original neutral position. ⑸To enable the production process to continue in the event of a failure or maintenance of the steam control valve, a bypass line should be provided for the steam electric valve. Special attention should also be paid to whether the installation location of the control valve meets the requirements of the process. ⑹The installation of the electrical components of the steam electric valve shall be carried out in accordance with the relevant construction requirements for electrical equipment. In the case of flameproof products, they shall be installed in accordance with the requirements of the \"Code for Installation of Electrical Equipment in Explosive Atmospheres\". If the wires on site are of the SBH type or other six-core or eight-core rubber-insulated cables with an outer diameter of around 11.3 mm. During maintenance, it is strictly prohibited to power on and open the cover in explosive environments, as well as to pry at the flameproof surface. At the same time, avoid damaging or scratching the flameproof surface during disassembly and assembly, and restore it to its original flameproof condition after maintenance. ⑺After disassembling and repairing the reducer of the actuator, attention should be paid to lubrication by adding oil; low-speed motors generally should not be disassembled, cleaned, or lubricated. After assembly, it is also necessary to check whether the valve position matches the indication of the valve opening degree.