Pneumatic valve maintenance should pay attention to the problem

With the rapid development of China's industry, pneumatic valves in metallurgy, petrochemical and other fields are more and more widely used, its stability, reliability is also becoming more and more important, its working status will directly affect the automatic control process, Xiaobian will elaborate on the use and maintenance of pneumatic valves. The newly designed control system of the device, in order to ensure that the regulating valve can work normally when driving, and make the system operate safely, the new valve should first check whether the nameplate mark on the valve is consistent with the design requirements before the installation. The following projects should also be debugged. Basic error limit; Full stroke deviation; Return difference; Dead zone; Leakage amount (in the case of strict requirements). If the regulating valve in the original system is overhauled, in addition to the above verification, the sealing of the stuffing box and joints of the old valve should be checked. In the field use of the regulating valve, many are often not caused by the quality of the regulating valve itself, but by the improper use of the regulating valve device, such as the device environment, the device position and direction, or the pipeline is not clean. Therefore, the pneumatic valve should pay attention to the following aspects when using the device: (1) The regulating valve belongs to the field instrument, and the ambient temperature should be in the range of -25 ~ 60 ° C, and the relative humidity should be less than 95%. If the device is in the open air or high temperature occasions, waterproof and cooling measures should be taken. In the place where there is a source, it is necessary to stay away from the vibration source or increase anti-vibration measures. (2) The regulating valve should generally be vertically installed, and in special cases it can be tilted, such as when the tilt Angle is large or the valve itself is too heavy, the valve should be protected by increasing the supporting parts. (3) The pipeline of the device regulating valve is generally not too high from the ground or the floor, and the platform should be set as far as possible when the height of the pipeline is greater than 2m, so as to facilitate the operation of the handwheel and facilitate maintenance.(4) The pipeline should be cleaned before the regulating valve installation to remove dirt and welding slag. After the device, in order to ensure that no impurities remain in the valve body, the valve should be cleaned again, that is, all valves should be opened when entering the medium, so as not to jam impurities. After using the handwheel mechanism, it should be restored to the original neutral position. (5) In order to enable the control valve to continue the production process in the case of failure or maintenance, the control valve should be provided with a bypass pipeline, as shown in Figure 1-1. At the same time, special attention should be paid to whether the installation position of the regulating valve meets the requirements of the process. (6) The electrical part of the pneumatic valve shall be carried out according to the construction requirements of the relevant electrical equipment. Such flameproof products should be installed in accordance with the requirements of the "Code for Electrical Equipment Installation in Explosive Dangerous Places". For example, the site wire adopts SBH type or other six or eight core rubber device cable with an outer diameter of Φ11.3mm. In the use of maintenance, it is strictly forbidden to open the cover of the explosive place and pry the flameproof surface. At the same time, do not hurt or scratch the flameproof surface during disassembly, and restore it to the original flameproof requirements after maintenance. (7) The reducer of the actuator should pay attention to refueling and lubrication after disassembly and repair, and the low-speed motor should not be disassembled, washed and refueled. After assembly, the valve position should also be checked to see if it is consistent with the valve position opening indication.