Pneumatic component ?maintenanceIn the operation

by:AIRWOLF     2020-06-18
of machinery, pneumatic valve plays an important role, the use of it must not only be very skillful, quality should also be guaranteed at the same time, this will require the necessary maintenance of pneumatic valve, valve and maintenance need with scientific attitude, to make the valve maintenance work to achieve the purpose of the effect and application.Daily maintenance of pneumatic valves:1, the valve should be stored in a dry and ventilated room, the two ends of the path must be blocked.2. Valves stored for a long time should be inspected regularly to remove dirt and apply anti-rust oil on the processing surface.3. After installation, regular inspection shall be carried out. Main inspection items :(1) wear condition of sealing surface.(2) Trapezoidal thread wear of stem and stem nut.(3) Whether the packing is out of date and should be replaced in time if damaged.(4) Sealing performance test shall be carried out after valve overhaul and assembly.Notes for use and maintenance of pneumatic valves:1. The purpose of operation and maintenance is to extend the life of the valve and ensure the reliability of opening and closing.2, stem thread, often with stem nut friction, to apply a little yellow dry oil, molybdenum disulfide or graphite powder, lubrication.3, not often open and close the valve, also want to turn the handwheel regularly, add lubricant to the stem thread, in order to prevent biting.4, outdoor valve, valve stem with protective cover, to prevent rain, snow, dust rust.5. If the valve is mechanical, add lubricating oil to the transmission on time.6. Always keep the valve clean.7. Always check and maintain the integrity of other parts of the valve.If the fixed nut of the handwheel falls off, it should be fully matched and cannot be used, otherwise it will grind the square of the upper part of the valve stem, gradually lose the reliability of coordination and even cannot be started.8, do not rely on the valve to support other heavy objects, do not stand on the valve.9, stem, especially the threaded part, always wipe, to have been dusty lubricant to change to a new, because the dust contains hard debris, easy to wear thread and stem surface, affect the service life of pneumatic single-seat control valveFolding debugging methodPneumatic valve positioner is one of the most important pneumatic accessories for pneumatic control valves, which realizes the function of receiving control signals to accurately position the valve travel position.Function of pneumatic valve positioner: Pneumatic valve positioner and pneumatic actuator jointly constitute the automatic control unit and various control valve connection after debugging and installation, combined into a pneumatic control valve.Pneumatic valve positioner is used in a variety of industrial automation process control fields.Pneumatic control valve factory, locator and control valves are done calibration, but often after loaded on the pipeline valve needs to make another calibration, conventional calibration method is: 5 points calibration is 4 ma, ma, ma, ma, 20 ma, in the case of 12 ma locator stem in a horizontal position, the other groups of signal valve position should be in % 0, 25, respectively 75% and 100% of stroke, and feedback rod rotation Angle is less than plus or minus 45 degrees.The deviation between zero and full can be corrected by adjusting the corresponding screw separately. Under normal circumstances, if the valve stroke corresponds to the given signal, the calibration is completed.A major problem when the valve is closed is how to achieve tight closure of the valve seat full load.The usual approach is to calibrate the valve so that the closing part (such as plug, diaphragm, plate, etc.) is positioned exactly against the seat, rather than ensuring that the closing part is fully against the seat.Appropriate seal loads must be designed to maintain design leakage and avoid corrosion of seal surfaces.Single acting pneumatic actuators are usually designed with thin film.In this design, the spring is used to reduce seat load and to withstand full closure pressure.Typical double acting pneumatic actuators adopt piston design.In this way, unlike the thin-film design, the supply pressure does not need to be restricted and full load supply pressure can be applied in order to achieve a higher closing pressure.For piston designs, the higher the pressure, the greater the stability and control sensitivity of the valve.
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