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Timely resolution of current limiting sampling valve faults is the key to ensuring the accuracy of analytical data
Date: 2025-12-15Read: 0
As a key component in process analysis, environmental monitoring, and laboratory gas/liquid sampling systems, the core function of the current limiting sampling valve is to accurately control the flow rate of trace samples while ensuring stable system pressure. However, in long-term operation, problems such as abnormal flow, leakage, or blockage often occur due to impurities in the medium, improper operation, or environmental factors. Timely identification and proper handling of these issues with the current limiting sampling valve are key to ensuring the accuracy of analysis data and the safe operation of the system.
1、 Unstable or low traffic
Reason: The filter or restriction hole is blocked by particles, crystals, or oil stains; Poor fluidity due to high viscosity or low temperature of the medium.
Solution: First, close the upstream and downstream valves, release pressure, and then disassemble the valve body. Use ultrasonic cleaning or appropriate solvents (such as anhydrous ethanol, acetone) to soak and clean the flow limiting element and filter screen; If it is crystal blockage, it can be softened with a warm solvent before cleaning. During installation, it is necessary to confirm the cleanliness of the medium. It is recommended to install a precision filter (such as 5 μ m) in front of the valve.
2、 Leakage at valve body or joint
Reason: Aging and scratching of the sealing ring; The threads are not tightened or mismatched joints are used; Frequent disassembly leads to wear on the sealing surface.
Solution: Replace the original specifications of FKM or PTFE sealing rings; Use a torque wrench to tighten according to standard torque (to avoid over tightening and crushing the seal); For the sleeve type connector, ensure that the pipe is cut flat and inserted in place before locking the nut. Do not use raw material tape to wrap around high-pressure gas interfaces.
3、 The switch is not flexible or stuck
Reason: Internal valve core fouling and corrosion; Spring failure; Lubricating grease solidifies in low temperature environments.
Solution: Conduct regular preventive maintenance and move the valve several times every 3-6 months to prevent adhesion; For corrosive media, 316L stainless steel or Hastelloy alloy valve bodies should be selected; Low temperature grease or tropical insulation can be selected for use in cold environments.
4、 The actual flow rate deviates significantly from the nominal value
Reason: The limiting aperture has increased due to erosion and wear; Deviation of medium pressure or temperature from design conditions; No on-site calibration has been conducted.
Solution: Verify the actual output flow rate using a calibrated electronic flowmeter; If the deviation continues to increase, the current limiting core needs to be replaced; At the same time, ensure stable upstream pressure and install stabilizing valves if necessary.
5、 System contamination or overpressure caused by misoperation
Risk: Rapid opening of the valve may cause pressure shock; Failure to close the sampling in a timely manner resulted in continuous loss of the medium.
Countermeasure: The valve should be slowly opened/closed during operation; Install solenoid valves and PLC interlocking in the automation system to achieve timed sampling and automatic cut-off.