Xylem FHF SHF - Manual (Page 22)

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7. Maintenance
Maintenance operations must be performed by skilled and qualified personnel only. Use suitable
equipment and protection devices. Observe the accident prevention regulations in force. If you
need to drain the pump, make sure that the drained liquid does not cause damage or injuries.
7.1 Checks
- Periodically check that the pump is working properly without generating any abnormal vibrations.
- Make sure there are no visible leaks in the mechanical seal.
- When the pump is off, check the alignment and wear of the flexible coupling com
ponents. If the flexible element shows signs of wear it must be replaced.
7.2 Dissasembling
The reference number of each individual component can be found in the exploded views Figs. 10-11,
pages 92÷94.
The hydraulic and internal pump components can be disassembled without disconnecting the pump
body and the suction and delivery pipes from the system.
Before starting to disassemble the pump, make sure that the motor is disconnected from the
power supply and that the pump cannot be started accidentally.
Close the gate valves on the suction and delivery sides, then remove the drain plug and drain the pump
body. Remove the coupling protection. If the coupling has no spacer, remove the motor together with its
semi-coupling. If a spacer has been fitted, remove it and leave the motor fastened to the base.
Loosen the screws that fasten the support to the base, then the ones that fasten the support to the pump
body. The support together with the rotating hydraulic part can be removed from the pump body to allow
access to the impeller, mechanical seal and wear rings for inspection, cleaning and replacement.
7.3 Re-assembling (see fig. 9, page 90)
Accuracy and cleanliness are essential when reassembling the mechanical seal. Remove any calcium
deposits or other foreign matter from the shaft and seat of the fixed element in the seal housing. Moisten
the shaft, the seat of the fixed element and the mechanical seal gaskets with alcohol to facilitate their
sliding into position.
Fit the fixed seal ring into its seat in the back plate by pressing it with your fingers or by means of a clean
wood or plastic tap. Insert the rotating part about 20 mm into the shaft, taking care not to damage the
gaskets against the shaft edges (use a pointed guide bush of hardened stainless steel having the same
external diameter as the shaft in its end section and slightly smaller in the initial section). Press the narrow
part of the spring with your fingers until the two lapped surfaces touch. Mount and secure the impeller
and complete the assembly following the disassembly procedures in the reverse order. Align the unit
following the alignment procedure described in paragraph 5.4.
WARNING
001073145_L_F_02-11:001073145_L_E_12-10 21-02-2011 16:44 Pagina 22