Regarding the issue of the piston rod rising?
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The instrument probe on the piston rod of one reciprocating machine shows an upward movement； I was wondering; normally, it should sink. There are no abnormalities in terms of pressure, flow rate, and temperature of the reciprocating machine. My guess is that the sensor of the gauge is broken ； The instrument technician is also puzzled; those who called us for repairs suggest that the current solution is to replace the probe with a new one and see if that works ； What do you think?
It’s normal for the piston rod to rise as well; during operation, the piston can rise due to the influence of air currents. Check that the upward movement of your piston rod should be expressed as a positive or negative value
I don’t know what level this is at; with the piston rod at rest, it definitely sinks, and the gap at the top is larger than that at the bottom； During operation, even though air currents exert a pushing force, there is a brief upward movement; under the effect of gravity, the piston rod still moves downward. Its normal operating state is indeed one of moving downward. So first, check the gauge probe and replace it if necessary; after replacement, continue to monitor it. Secondly, if there is a chance, after disassembly check whether there is any wear on the upper part; in my experience, wear on the upper part is abnormal. The upward movement I’m experiencing here is caused by the drop of the support ring retainer, which leads to friction between the piston and the cylinder, as well as wear on the upper part of the piston rings.
For the 4M80 model, the vertical deviation of the piston rod ranges from +0.076 mm to 0.0192 mm; therefore, it is possible that the piston rod is experiencing the upward movement you mentioned.