How to inspect a installed pneumatic control valve?

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How to inspect a installed pneumatic control valve? Engineers responsible for the acceptance of engineering systems or instruments often encounter this issue. The acceptance of pneumatic control valves can be carried out from seven aspects, and this post provides a detailed explanation of the steps and methods for such acceptance. 1. The coating on the surface of the housing components of the pneumatic control valve is smooth, intact, and free from rust; there are no deposits or oil accumulations on the surface. 2. The valve is firmly installed and not loose; its components are intact, the installation location is appropriate for easy maintenance, the fasteners are neither loose nor damaged, and the movable parts operate smoothly and reliably without any jamming. 3. The travel switch connected to the pneumatic control valve is clean, free of deposits or oil buildup, and is securely installed without any looseness. 4. Acceptance criteria for pneumatic actuators: Changhui Instruments, yunrun.com.cn. The surfaces of components such as the casing, pipelines, accessories, and links of pneumatic actuators should have smooth and intact coatings, without any rust; there should be no accumulation of liquid or oil on these surfaces ； The pneumatic actuator is firmly installed and not loose; its components are intact, and it is positioned in a way that facilitates maintenance. The fasteners are not loose or damaged, and the moving parts operate smoothly and reliably without any sticking ； The local operation button indicator device of the pneumatic actuator is complete, and the status indication is correct ； The external travel switch is clean, free from dust and oil accumulation; it is firmly installed and not loose, and its position should be adjusted correctly ； The nameplate of the pneumatic actuator should be complete, clear, and clean ； The gas supply pipeline is properly connected with no leaks; the handles for the primary and secondary valves are intact, and the nameplates have clear markings ； The wiring of the local control mechanism is neat, the nameplates are clear and match the design installation drawings. The connection points for items such as the five-way valve and filter air supply pipelines are in good condition, firmly installed, with no signs of air or oil leakage ； The cables of the actuator are neatly connected and properly insulated; the cable labels are accurate and clear; the cable openings are properly sealed ； The solenoid valve windings should have no open circuits or short circuits, and the wiring must be secure and correct ； The status indicators on the operator station screen are correct, and the operation menu is clear and reliable ； The equipment register is filled out correctly, with neat and clear handwriting ； Check the operation of the pneumatic actuator using a manual control signal; it should move smoothly and flexibly, without any sticking or jittering, and the time required to complete one full stroke should comply with the manufacturer’s specifications ； Check that the opening degree of the pneumatic actuator corresponds to the opening degree of the control mechanism and the indication on the valve position indicator ； Valves equipped with triple shutdown protection should ensure that they lock in a closed position when the control signal is lost ； Actuators equipped with self-locking protection should have their self-locking function checked one by one ； The valve positioner has a clean appearance, and all its components are firmly connected, with no looseness ； For pneumatic actuators with remote and local control, a full-range test of each control mode should be conducted once; the time taken for the switch to complete one full stroke should correspond accordingly ； Pneumatic control valves should undergo a air-disconnection test to determine the accuracy of their position when the air supply is cut off. 5. Gas source maintenance standards. Close the manual air supply valve, disconnect the air supply pipe fitting at the valve body, then open the manual air supply valve to purge the pipeline for 1-2 minutes ； Close the manual valve for the gas supply, reconnect the gas supply pipe fitting, and verify that there are no leaks at the fitting ； If there is a leak, the seal ring must be replaced or corrective action taken ； The air supply for the pneumatic regulator and the external pipes of the control system must be connected accurately, firmly, and leak-free ； All components are installed in the correct positions ； Air-open control valves use positive-acting positioners and positive-acting regulators; air-close valves are the opposite of air-open valves, and no errors can occur at any stage ； The regulator has no leaks in the simplified version, and the pneumatic valve operates without sticking. 6. Are the materials proving the valve material, as well as the instructions and certificates for pneumatic control valves and valve positioners, complete? It is very important to properly keep the instructions for pneumatic control valves and valve positioners, as they will be needed for future inspection and maintenance work. 7. Design drawings related to pneumatic control valves.