Impeller wear ring

Liquid Casing Wear Rings Impeller Wear Rings Shaft Shaft Sleeves Type of Seal Seal Cage Gland Remarks... 

Pumps shall use throat bushings, wear rings, impeller balance holes and/or flushing line arrangements for the following ... 

Wear-ring clearances are excessive (closed impeller design). 

Excessive wear ring (closed impeller) or cover-case clearance (open impeller). 

Replace wear rings or adjust axial clearance of open impeller. In severe cases, cover or case must be replaced. 

As we ve di,seussed, system design is responsible for much of cavitation. Yet, the maintenanee mechanic is responsible for stopping and preventing eavitation. And certainly, it s the maintenance mechanic who has to deal with the results of cavitation, the constant changing of bearings, meehanical seals, damaged impellers, wear rings and other pump parts. 

The scratch marks on the circumference of these close tolerance rotary parts will correspond to. scratch marks on close tolerance stationary parts at approximately 60 around the volute from the cutwater. These marks will be vi.sible on the back plate with open impellers, or on the wear rings of pumps with enclosed impellers, or the ID bore of the restriction bushing at the bottom of the seal chamber where the shaft pa.sses through, or the ID of the seal chamber bore at the back end of the mechanical seal (Figure 9-6 and Figure 9-7, next page). 

Erosion is the wear of the pump internal parts by suspended solid particles contained in the fluid being pumped. The most affected parts are wear rings, shaft sleeves, packing, mechanical seal faces, lip seals, the pump casing and the impeller. 

Wear rings provide for a close running, renewable clearance, which reduces the amount of liquid leaking from the high pressure zones to the low pressure zones in the pump. They are commonly fitted in the pump easing and on the impeller (Figure 16-1, next page). 

IMPELLER WEAR RING COOLING WATER-SEAL ... 

Wearing plates With open type impellers or end clearance wearing fits, these perform the same purpose as wearing rings do with radial clearances. 

SHAFT is heat treated, extra heavy to take maximum radial thrust. Shaft supports impeller between bearings for longer bearing, wearing ring and packing life. 

Unless otherwise specified, renewable wear rings shall be furnished on both the casing and the impeller. Front and back wear rings shall be furnished, if required, for axial balance. Pumping vanes shall not be used to establish axial balance. 

Impeller wear rings No Cast iron Bronze Cast iron Ni-resist Cast iron 12% CHR Hardened 12% CHR Hardened Hard faced 316 AUS (3) Monel 12% CHR hardened Hard Faced AUS (3) Hard Faced 316 AUS (3) Duplex (3)... 

Impeller Wear Rings No Cast Iron Bronze Cast Iron Ni-Resist Cast Iron 12%CHR Hardened 12% CHR Hardened Hard-faced 316AUS6 N-Cu Alloy 12% CHR Hardened Hard-faced AUS Hard-faced 316 AUS Hard-faced Duplex Hard-faced Super Duplex ... 

Impeller wear ring—minimized internal liquid leakage, from the pump discharge, back to the pump suction... 

The clearance between the impeller and the impeller wear ring (Fig. 23.6) may have increased as a result of wear. 

In order to reduce the leakage of water from the discharge to the suction side of the impeller wearing rings are used. Preferably they are made separate from the impeller so that they may be renewed if worn. They also serve to balance the outer part of the impeller, both sides of which will be subject to the same pressure. The H... 

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