Impeller adjustment Of The Vertical Turbine Pumps (VTP pumps)

Proper impeller adjustment positions the impeller inside the bowl assembly for maximum performance. The impellers must be raised slightly to prevent them from dragging on the bowls, but not raised too high so as to adversely affect hydraulic performance.

The impeller must be down against the bowl seat

when starting impeller adjustment. When Vertical Turbine Pumps (VTP pumps)

 are subjected to suction pressure, the pressure acting against the shaft tends to raise it. Make sure the shaft is down when starting to adjust the impellers.

If, after making the impeller adjustment the  Vertical Turbine Pump does not deliver its rated capacity, the impellers can be lowered one step at a time until the lowest possible adjustment is achieved without the impellers dragging. On the other hand, if the impellers appear to be dragging after the initial adjustment, the unit should be stopped and the impellers raised one step. Dragging impellers will increase the load significantly and can usually be heard and felt as increased vibration. A sharp rise in motor amperage will occur when impellers are dragging.

Impeller adjustment for a solid shaft driver

Impeller adjustment when using solid shaft drivers is accomplished in the adjustable flanged coupling.

located below the driver.

Adjusting adjustable flanged coupling

a) Assemble coupling on  Vertical Turbine Pump shaft and driver shaft (if not installed earlier).

b) Check motor direction of rotation.

c) Check and write down Flowserve recommended impeller setting for final adjustment.

d) Pump to motor alignment and final coupling

• Mount two magnetic indicator bases on the discharge head at 90 degrees to each other

• Set the indicator tips on the shaft just above the seal and at 90 degrees to each other. (Usually parallel and perpendicular to the discharge nozzle) push the shaft (parallel to discharge) back and forth (without bending shaft)

• Note and record the minimum and maximum indicator readings. Do the same procedure at 90 degrees to the discharge (See Figure A).

• Set the shaft in the center of the maximum and minimum indicator readings both directions. If the shaft will not stay in this position, use small wooden wedges between the shaft and seal bolts to hold the shaft. The indicators can now be removed

• Alternate method for  Vertical Turbine Pump with packing:

Using an inside micrometer, measure the space between the shaft and the packing box bore. Do this both parallel and perpendicular to the discharge nozzle

Using the wedges center the shaft so the measurements taken at 180 degrees to each other are within 0.10 mm (0.004 in.) of being equal (For pumps using jackscrews for motor go to step f).

e) Mount the magnetic base on the drive half

coupling (a band clamp may be necessary to hold base due to limited space). Position the tip of the indicator on the  Vertical Turbine Pump shaft just above the seal. Slowly rotate the driver shaft. (See Figure A).

If a register fit is used for alignment, driver will be able to be moved only a few thousandths of an inch. If enough movement is not obtainable then the male register can be filed to obtain acceptable T.I.R. readings (Go to step g).

f) On Vertical Turbine Pumps (VTP pumps) using jackscrews for motor alignment, mount the dial indicator base on the O.D. of the motor half coupling. Set the indicator on the shaft, position the dial to zero being careful that the indicator is in direct line with one of the jackscrews. Record this reading then rotate the motor shaft and indicator 180 degrees.

Record this reading being careful to note plus or minus values. Take the difference of the two readings and using the jackscrews move the motor one half of the difference. Repeat this step until the T.I.R. reading is a maximum of 0.05 mm (0.002 in.).

Then repeat this step for the set of jackscrews located 90 degrees to the first set. Once all readings are within 0.05 mm (0.002 in.) tighten motor bolts and check for any movement in readings.

g) Set the impeller setting gap between the adjusting nut and the driver portion of the coupling. See impeller setting data supplied along with the pump. If this information is not found, contact Flowserve. Align the match marks on the pump half coupling with the driver half coupling. On Vertical Turbine Pumps (VTP pumps) with enclosed impellers the match marks can be lined up by increasing the impeller gap until the marks are in line with the driver half coupling marks.

On Vertical Turbine Pumps (VTP pumps) with semi-open impellers, the match marks probably will not be in line when the gap is set. DO NOT try to align the marking on the nut with the other markings.

For Vertical Turbine Pumps (VTP pumps) with enclosed impellers go to step (h).

h) Using 2 bolts of the coupling, at 180 degrees to each other, slowly raise pump half coupling until impellers are just lifted off the seat (This can be gauged by trying to turn shaft by hand. At the point the impellers are lifted the Vertical Turbine Pump will turn).

Be sure to lift both sides evenly.

i) Measure the resultant gap between the motor half coupling and the adjusting nut.

j) Find the difference between the original gap and the new gap. Add this difference to the original gap and reset the adjusting nut.

k) Bolt the coupling together and tighten bolts by tightening opposite sides.

l) Remove wooden wedges, if used. Mount magnetic base on Vertical Turbine Pump and set the tip of indicator on the shaft just above the seal. Slowly rotate the shaft and note the T.I.R. reading.

If the reading is larger than the allowable values specified above, unbolt the Vertical Turbine Pump and rotate the driver portion of the coupling to different hole and repeat steps (h) and (i) until acceptable readings are obtained.

m) If a mechanical seal is used, adjust the mechanical seal at this time.