Centrifugal Compressor - Shaft`s Axial Displacement Sensors setting on zero position(Thrust Bearings

[NICU OVIDIU]

I know that there are two consecrated variants namely by (1)running the machine thus the rotor is pushed into its standard operating position, indicated as zero position or (2)by placing the rotor in the middle of thrust bearing clearance(total float), indicated as zero position as well.

My question refers to the latest(second) version of zero position setting, when using the dial gauge to measure shaft`s total float(between thrust bearings), is it absolutely necessary to apply a certain thrust(simulating/creating real operation condition) or it is just enough to push the rotor(without applying any additional force) , back & forth, until the thrust collar touches the Thrust Bearing (Active & Non-Active) pads ?

Thank you advise,

 

[rQuestionEngineering]

Theoretically you need a certain amount of force applied. In one case, where the thrust bearing is Kingsbury, you need about 50 to 150 psi push.

Practically, on site, we ignored the force. Take a reading of 5 times and average the float, no force. Once end float is determined, you divide it to half and place the rotor there.

Hope this help your job to move forward.