Calibration issues of pneumatic diaphragm regulating valve
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When adjusting on site, 0% and 100% correspond to the scale 0 and 100, but 25% corresponds to the scale 20, and 75% corresponds to the scale 80. How to adjust this phenomenon?
It is very likely that the 50% alignment is not correct. When the valve position is at 50%, the feedback rod of the positioner should be perpendicular to the valve stem, so as to ensure linearity.
When installing the electric valve positioner, ensure that the feedback lever is in a horizontal position when the opening is 50%. If the deviation is too large, it will affect the linearity of the valve.
What was said above is very good, learn from it* Yes,
First determine whether the 50% opening is accurate. If it is inaccurate, it may be caused by the zero position being too low and the range being too large. This can be corrected by adjusting the zero position and range. If it is accurate, then the linearity of the positioner is not good. The possible reasons are as follows:: 1 Improper selection of feedback cam or spring ； 2 The feedback mechanism is not installed properly ； 3 Feedback cam or spring is improperly installed ； 4. The nozzle or baffle is contaminated. ； 6. There is a slight leakage in the back pressure. ； 7 Improper installation of the whole machine ； 8. The feedback connection rod face regulating valve is stuck.
Based on your question, let me answer you. It’s because your measuring range is longer. This question is simpler. It seems that you have just learned how to debug. If you have any questions, just ask me. If I know how, I will tell you everything. QQ: 346660472