Small issues that should be noted in the operation of multistage pumps(2)

Difficult rotation or friction of rotating parts

1) Bending of the shaft

Elimination measures: Straighten the shaft or replace as required.

2) Incorrect running clearance between wear rings

Elimination measures: Check if the clearance is correct. Replace the wear ring of the pump casing or impeller as required

3) Stress in the pipe on the pump casing is too large

Elimination measures: Eliminate the stress and factory representative consultation. After stress removal, check alignment

4) Shaft or impeller ring swing too large

Elimination measures: Check rotating parts and bearings and replace worn or damaged parts as required.

5) Dirt between impeller and pump casing wear ring, dirt in pump casing wear ring

Elimination measures: Clean and check the wear ring, and replace it as required. Isolate and eliminate the source of dirt.

Minor issues to be noted when repairing the pump

A small thing that is easily overlooked when assembling after repair

The centre line of the impeller outlet in the volute pump, i.e. the centre line of the impeller outlet width, should be aligned with the centre line of the volute inlet. If it is not aligned, it should be adjusted by adding shims to the impeller wheel enough and the shaft shoulder. The two centre lines should be controlled within a range of 0.5 mm. For the pump than the number of revolutions slightly worse than the pump performance is not a big impact, for the pump in the low than the speed of the impeller is very narrow, for example, the impeller outlet width of only 10 mm, if and volute in the line of 1 mm, the pump performance has a significant impact. It is recommended that the two centre lines (impeller and volute) can be adjusted to control the error within 5% of the impeller outlet width as well.

Note the error in controlling the impeller outlet centre line and guide lobe inlet centre line

Space guide vane pump, it is best to use the data given in the general assembly drawing to determine the position of the impeller in the space guide vane. If no drawing is available, or by experience, or by adjusting the position of the impeller through test results.