Maintenance Videos

Zeno Academy

Better Together
Zenit Group | 28 Mar 2018


Assembly - Complete mechanical seal dismantling and oil change procedure for Zenit UNIQA submersible pumps. The procedure also involves adjustment of the impeller and chopper knife clearance. Models with grinding system (ZUG GR) in WET version. Type DR1-D mechanical seals.
  1. Fit the rotation stop pin into the seat in the sealing flange and fix it with Loctite 641 threadlocker
  2. Fit the O-ring into place on the flange
  3. Fit the flange on the seat using a suitable driver and secure it with the snap ring, making sure it is perfectly snug
  4. With a felt-tip pen, mark the position of the pin on the flange and that of the relative seat in the counterface
  5. Wet the counterface with alcohol and fit it, aligning the marks
  6. Fit the counterface with a suitable driver
  7. Blow with compressed air to remove all traces of dirt and lubricate the counterface
  8. Clean the surfaces of the seal with a paper towel
  9. Fit the seal onto the shaft
  10. Grease the O-ring and fit it into the seal seat
  11. CAUTION to avoid damaging the seal, do not use metal tools
  12. Fit the case, aligning the slots correctly, and position it with the relative driver, which ensures the correct preload on the seal
  13. Tighten the 3 stud bolts, securing them with Loctite 243 threadlocker
  14. Remove the driver. Use an extractor screw if necessary
  15. Grease the seal and fit it onto the casing, taking care to position the slots correctly
  16. Fit the rotation stop pin into the seat in the pump plate and fix it with Loctite 641 threadlocker
  17. Wet the counterface with alcohol and fit it into the seat in the pump plate, positioning the pin and slot correctly
  18. Fit the seal with a suitable driver
  19. Clean the surface of the counterface with a paper towel
  20. Fit the counterface locking ring and fit the screws without fully tightening them. Use Loctite 243 threadlocker
  21. Lift the three wings of the ring and set them at an angle of about 60°, taking care that they do not interfere with rotation of the seal
  22. Fit the O-ring into the seat in the pump plate
  23. Fit the O-rings into the oil chamber screw seats
  24. Spray the seal with spray lubricant
  25. Fit the pump plate onto the oil chamber and fix it with the screws
  26. First tighten the screws by hand to fit it gradually into position.
  27. Fit a cap into one oil chamber hole and a compressed air fitting into the other
  28. Pour in a little alcohol to check for leaks
  29. Test for tightness at a maximum pressure of 1 bar
  30. Remove the cap and fitting
  31. Refit the handle so that the cable will not be crushed when handling the motor
  32. Lay the motor part horizontal on the workbench with the oil chamber caps upward
  33. Tighten the handle screws
  34. Fill the chamber with oil. Refer to the documentation for the correct amount
  35. Seal the oil chamber with the caps
  36. Place the impeller on the support
  37. With a hoist, lift the motor by the handle
  38. Fully tighten the impeller fixing screw. This is temporary.
  39. DO NOT use threadlocker!
  40. Place the pump on the workbench horizontal, taking care not to damage the impeller blades
  41. Measure the gap between the pump blade and plate with a gauge
  42. Measure the pump body height with a gauge
  43. Apply shims as necessary to obtain a clearance of 0.2 - 0.5 mm
  44. Remove the impeller fixing screw
  45. Fit the paper seals
  46. Mount the pump body and secure it with the fixing screws
  47. Use a feeler gauge to check that the impeller clearance is correct
  48. Fit the chopper plate
  49. Fit the chopper knife, using shims as necessary.
  50. Tighten the chopper knife fixing screw and secure it with Loctite 270 threadlocker
  51. Use a feeler gauge to check the clearance between the chopper plate and knife. Correct clearance 0.2 - 0.5 mm
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