Imported regulating valve maintenance does not move: This is a more common and significant fault. When there is no signal no air source, it may be that the air source is not turned on. In some newly installed or equipment that has not been used for a long time and thenactivated, this kind of low-level error is prone to occur. The air source contains water and freezes in winter, which can cause blockage of the air duct orage of the filter and pressure reducing valve, which is particularly common in the northern cold regions in winter. Compressor failure will also cause the air source to not be supplied. For example, wear of the piston of the compressor, poor sealing of the cylinder, etc., will affect its air volume, resulting in insufficient air source pressureLeakage of the air source main pipe can also cause the phenomenon of no air source. The sealing failure of the connection of the main pipe, the corrosion andation of the pipeline, etc., may cause leakage. When there is an air source but no signal, it may be a regulator failure, such as the damage of electronic components, resulting in the inability to output control signals; the leakage of the bellows steel of the positioner, which makes the signal transmission blocked; the damage the regulating diaphragm, which affects the perception and transmission of signals. The positioner has no air source, which is most likely a blockage of the filter Impurities accumulate in the filter, which hinders the passage of gas; the pressure reducing valve fails, which cannot adjust the air source pressure to an appropriate range; leakage or blockage, which makes the gas unable to reach the positioner smoothly. The positioner has an air source but no output, which is most likely aage of the positioner''''s throttle hole. Once the tiny throttle hole is blocked by impurities, it will block the signal output. There is a signal but no, which may be the valve core falling off, the connection between the valve core and the valve seat or valve stem is loose, resulting in the valve core being unable follow the signal action; the valve core and the valve seat are stuck, which may be due to the accumulation of impurities, crystallization in the medium between the core and the valve seat, or the decrease of the fit accuracy between the valve core and the valve seat, resulting in sticking phenomenon; the valve stem is bent or, mostly due to external impact, frequent vibration or long-term stress; the valve core is frozen or covered by coke dirt, which is prone to occur in some lowtemperature environments or media that are prone to crystallization and coking.