AMT 3941-96, Specifications Information And Repair Parts Manual, Page: 2 / 8

Specifications Information and Repair Parts Manual
3941-96, 3942-D6, 3943-96, 3944-96 & 3946-96
3941-252-00 2 6/2016
IMPELLER AND WEARPLATE REPLACEMENT
Impeller (Ref. No. 12), volute/wearplate (Ref. No. 14) and rear wearplate (Ref.
No. 5) are subject to wear only by abrasive sand or sediment laden liquids. If
badly worn, all these parts can be replaced easily and the pump thus restored
to full efficiency.
NOTE: When the clearance between the impeller and the volute/wearplate
exceeds 1/16” at the face of the impeller or 1/8” on the outside diameter of
the impeller, it may be necessary to take corrective action. The increased
clearance can cause lengthened priming and decreased capacity to your
unit. If performance is satisfactory for your application, it is recommended
that no corrective maintenance be performed regardless of what clearances
on your unit may have developed. This is because increased clearances in
themselves are not generally harmful to your pump. Normally, new pump
clearances can be restored by simply shimming behind the impeller. (Add
shim washers Ref. No. 11). If the impeller is badly worn, it is recommended
that the impeller be replaced. This is usually all that is required since only
on abrasive surfaces does the cast iron wearplate show deterioration.
Occasionally a stone or hard object might get caught in the impeller and
cause damage to the volute/cutwater. In these cases follow the instructions
below for replacement and refer to Figure 1.
1. Disassemble pump for access as described in Mechanical Seal
Replacement, steps 1 and 2.
2. Replace parts as necessary.
NOTE: When replacing volute/wearplate, attach flapper valve assembly (Ref.
No. 15) to the new volute with fastener (Ref. No. 16).
3. To replace rear wearplate (Ref. No. 5), remove fasteners (Ref. No. 6)
after impeller has been removed.
NOTE: Before Installing new parts, clean all mating surfaces thoroughly.
SUCTION FLANGE REPLACEMENT
1. Unthread the four screws on the suction flange (Ref. No. 28).
2. Remove the old gasket.
3. Replace the gasket. Gasket must be installed between suction flange
and casing for proper seal and priming.
4. Install new suction flange and thread the four bolts to the casing. Tighten
the bolts in an alternating pattern to avoid pinching
DISCHARGE FLANGE REPLACEMENT
1. Unthread the four screws on the discharge flange (Ref. No. 17).
2. Remove the old gasket.
3. Replace the gasket. Gasket must be installed between discharge flange
and casing for proper seal.
4. Install new discharge flange and thread the four bolts to the casing.
Tighten the bolts in an alternating pattern to avoid pinching
3-Inch Trash Pump
Figure 1 - Mechanical Seal Replacement