42 | IM-112 DECEMBER 2019
Vertical Turbine Pumps
2001299 - VTP- IOM
42 | IM-112 DECEMBER 2019
Vertical Turbine Pumps
2001299 - VTP- IOM
42 | IM-112 DECEMBER 2019
Vertical Turbine Pumps
2001299 - VTP- IOM
Vertical Turbine Pumps
Maintenance
Document Name: 2001299-VTP-IOM-EN Page 42 of 67
Revision 3 Copyright © 2014, Weir Floway, Inc. All Rights Reserved. Issue Date: December 12, 2014
7.5 Mechanical Seal Maintenance
Mechanical seals should not be readjusted unless there is a reason. Best results are obtained when the seal
is properly set at start-up and left that way. If the seal starts to leak after an extended operating period, some
readjusting can be done at that time. However, it is usually best to replace the seal during the next scheduled
maintenance cycle.
After impeller readjustment, seal leakage may occur due to improper seal adjustment or improper seating of
the seal parts.
7.6 Impeller Readjustment
Typically, impellers do not require readjustment if properly set at initial installation. Almost no change in
performance can be obtained by minor adjustment of enclosed impellers; however, the positioning of semi-
open impellers has a definite effect on the performance of the pump. This characteristic is sometimes used to
adjust the output of the pump without valving. Figure 7-1 on page 43 illustrates the general effect of raising
semi-open impellers.
After extended operation, the sealing faces between the semi-open impellers and the bowl will wear causing
a reduction in performance. The pump performance can be brought back up to almost “as new” by proper
readjustment of the impellers. Refer to “Impeller Adjustment - General” on page 29 for proper adjustment
procedure.
CAUTION
DAMAGE DUE TO MECHANICAL SEAL TABS
• For pumps fitted with mechanical seals always follow the seal manufacturer’s instruction
manuals.
• Always remove the mechanical seal setting tabs prior to starting the pump.
• Failure to remove the tabs will result in damage to both the pump and the seal.
• Ensure that the set screws are tight before removing the setting tabs.
If readjustment of the seal does not correct the problem, refer to the manufacturer’s
instruction manual for further information.
NOTICE
Adjusting the impellers will change the mechanical seal setting unless the seal is loosened
from the shaft. It is recommended to first loosen the seal from the shaft, perform the
impeller adjustment, then reset the mechanical seal.
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