Combining equipment characteristics and practical operating experience, the clearance adjustment of the balance drum and balance disk in a balance disk-drum multistage pump centers on "set standards first, measure accurately, then fine-tune and secure". The entire process is colloquial and easy to operate, with specific steps as follows:
The conventional radial clearance of the balance drum is 0.2–0.5 mm, and the axial clearance of the balance disk is generally 0.1–0.3 mm (use smaller values for small pumps and adjust slightly for large high-pressure pumps; always prioritize the equipment manual). This is the adjustment baseline and must not rely on experience alone.
Shut down and disconnect power first, disassemble the pump casing to expose the rotor components, clean oil stains and rust from the surfaces of the balance drum and balance disk, and address any wear marks beforehand. Prepare tools such as feeler gauges, dial indicators, and wrenches to avoid inaccurate measurements.
Push the rotor toward the suction end so that the balance disk fits tightly against the balance ring. Take 3–4 measurements at the clearance with a feeler gauge and calculate the average to obtain the actual clearance. Measure the radial clearance of the balance drum using the same method to confirm the deviation between the current value and the standard.
Balance disk:
If the clearance is too large, loosen the shaft sleeve lock nut and screw the balance disk toward the balance ring.
If the clearance is too small, turn it in the opposite direction, or grind the balance disk end face and add/remove gaskets. Re-measure after each adjustment.
Balance drum:
If the clearance does not meet the standard, shorten or lengthen the adjusting sleeve, or add/remove washers behind the adjusting sleeve until it falls within the standard range.
After adjustment, use a dial indicator to verify that the rotor axial movement is within specification. Tighten the lock nut and re-measure the clearance once more to prevent shifting. Finally, reassemble the pump casing, start the pump for a trial run, and check that vibration and temperature are normal. The adjustment is complete if no issues are found.
Key reminders:
Apply force evenly during adjustment; do not use excessive force to avoid thread stripping. If abnormalities occur during operation, shut down the pump and recheck the clearance. Replace components promptly in case of severe wear.