The clearance issue of the balance disk
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What happens if the balance disc clearance in a multi-stage pump is too large, and what happens if it is too small?
Balance disc clearance? This gap is not fixed; it adjusts automatically based on the pressure difference
I know this. When the pump is in operation, it uses pressure difference to push the balance disc aside; however, a gap must be left during installation. Without this gap, the balance disc will stick and prevent the pump from rotating. What I want to know is what happens if the gap left for the balance disc is too large or too small.
Neither too large nor too small can achieve balance
The clearance of the balance disk is very important; it must be maintained during maintenance. Especially for balance discs with radial clearance control, it is difficult to control them, and it is important to do so properly. The larger the gap, the greater the thrust force; a thrust bearing that has to bear more load experiences an increase in temperature. If the gap becomes smaller, the thrust force may decrease, but the thrust disc is prone to rubbing against the pump’s components (due to vibrations), which can cause the pump to experience greater vibrations. Therefore, the balance disc used to regulate this radial clearance must possess the technical capability to maintain the optimal clearance value. The principle of the balance disc for axial clearance control is the same, but it is simpler to maintain.
The balance disc clearance should be maintained between 8 and 10 turns. If it exceeds this range, the rotor will keep trying to reach this value during normal operation. The thrust bearing will be under stress