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1. Operation of valves and flow meters for oil switching
During oil switching, the operation of valves and flow meters must strictly follow safety regulations and accuracy control requirements, with the core being to ensure smooth switching, prevent oil mixing, and ensure accurate measurement. 1. Before switching valve operations: Confirm the initial state of the valve. The valve to be closed should be tightly closed, and the valve to be opened should be in the closed to open state; Check for valve jamming and other abnormalities; Determine whether to open the bypass valve in advance to balance the pipeline pressure according to the process requirements. Switching: The operation must be slow. First, slightly open the valve of the target oil pipeline, and then gradually increase it after the pressure stabilizes; Follow the sequence of opening first and then closing, that is, first open the target oil pipeline control valve, and then close the original oil pipeline valve. After switching: check the sealing of each valve and observe for leaks; Lock the operated valve to prevent accidental operation. Before switching between front and rear use of the flowmeter, check whether the flowmeter is working properly and whether the accuracy meets the requirements; If there is a bypass pipeline, it can be considered to bypass first during the initial switching period to avoid impurities or bubbles from impacting or affecting the precision measuring equipment. Switching: closely monitor changes in traffic indicators to determine if the switching process is smooth; Be careful to prevent gas from entering the flowmeter and perform exhaust operations if necessary. After switching: After the system runs stably, calibrate the fl
2. Industrial gas flowmeter displays valve closed
Troubleshooting solution for industrial gas flowmeter displaying valve closed
1. Problem diagnosis steps 1 Valve status confirmation check whether the mechanical indicator or actuator of the valve is in the closed position. If it is an electric/pneumatic valve, it is necessary to check whether the control signal (4-20mA or switch quantity) is delivered to the actuator normally. 2. Flow meter signal verification: Use a multimeter to accompany the technician to detect the output signal of the flow meter (such as pulse, analog quantity), compare the actual working condition with the displayed value. If the signal is normal but the display is abnormal, it may be a fault in the internal calculation unit of the flow meter. 3. Check the control system logic to see if the PLC/DCS system logic has set automatic valve closing conditions (such as flow rate exceeding limit, emergency cut-off trigger), and check if the associated sensor (such as pressure, temperature) data is abnormal.
II. Common causes and solutions | Types of faults | Specific manifestations | Solutions | |: --- |: --- | | Signal transmission interruption | Line break, electromagnetic interference | Detection of cable connectivity, installation of shielding tube | | Execution mechanism failure | Motor overload, insufficient gas source pressure | Reset overload protection, check gas path pressure ≥ 0.4MPa | | Sensor failure | Flow meter zero drift, electrode contamination | Re calibrate according to manual, clean sensor components | | Control system errors | Program logic errors, module failures | Check pr
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