AMT 3931-99 Specifications Information And Repair Parts Manual

Specifications Information and Repair Parts Manual
Please read and save this Repair Parts Manual. Read this manual and the General Operating Instructions carefully before attempting to assemble, install, operate
or maintain the product described. Protect yourself and others by observing all safety information. The Safety Instructions are contained in the General Operating
Instructions. Failure to comply with the safety instructions accompanying this product could result in personal injury and/or property damage! Retain instructions
for future reference. AMT reserves the right to discontinue any model or change specifications at any time without incurring any obligation.
©2016 AMT Pump Company, A Subsidiary of The Gorman-Rupp Company, All Rights Reserved.
Periodic maintenance and inspection is required on all pumps to ensure proper operation. Unit must be clear of debris and sediment. Inspect for leaks and loose bolts. Failure to do so
voids warranty.
2-Inch Trash Pedestal Pumps
Refer to pump manual 1808-635-00 for General Operating and Safety Instructions.

DESCRIPTION

This self-priming (to 20 ft. lift) centrifugal pump includes a clog-resistant, open impeller capable of handling solids as large as 1" diameter (up to 25% by volume).
A built-in check valve assists in priming and a mechanical seal prevents leakage. All seals are Buna-N. Handles liquids from 40º to 180º F (4º to 82º C). For use
with nonflammable liquids compatible with pump component materials.

MAINTENANCE

Make certain that unit is disconnected from power source before
attempting to service or remove any component!

CLEANING

This unit has been designed with a removable volute enabling pump to be
cleaned or unclogged with ease. Remove casing and volute as described
in steps 1 and 2 under MECHANICAL SEAL REPLACEMENT. Remove any
debris found inside unit, reassemble as described in steps 16 and 17 under

MECHANICAL SEAL REPLACEMENT.

NOTE: Depending on application, it may be necessary to remove suction and
discharge hoses.
MECHANICAL SEAL REPLACEMENT
Refer to Figures 1 and 2.
IMPORTANT: Always replace seal seat (Ref. No. 12), seal head (Ref. No. 13),
and shaft sleeve (Ref. No. 14) to ensure proper mating of mechanical seal
components!
1. Unthread cap screws (Ref. No. 22) and remove casing (Ref. No. 20) and
o-ring (Ref. No. 11) from adapter (Ref. No. 10).
2. Unthread round head screws (Ref. No. 17) and remove volute (Ref. No.
18) from adapter.
3. Unscrew impeller (Ref. No. 9) from pump shaft (Ref. No. 5). Remove
impeller shim(s) (Ref. No. 15), shaft sleeve and seal head from pump
shaft.
4. Unthread hex flange screw (Ref. Nos. 7 & 8) and remove adapter from
pedestal mounting face.
5. Push seal seat from adapter recess with a screwdriver.
6. Clean adapter recess before inserting a new seal seat.
7. Carefully wipe polished surface of new seal seat with a clean cloth.
8. Wet the outside of rubber portion of seal seat with a light coating of soapy
water.
9. Press new seal seat squarely into cavity in adapter. Use finger pressure

Performance Chart

Power Requirement
5HP @3600 RPM
(**) Shutoff; to convert to psi, divide by 2.31.
3931-250-00
10' 20' 30'
155 145 134
only to avoid scratching seal seat. (This is a lapped surface and must be
handled very carefully.)
10. After seal seat is in place, be sure that it is clean and has not been marred.
11. Using a clean cloth, wipe shaft and make certain that it is perfectly clean.
12. Secure adapter on pedestal mounting face.
Tighten hex flange screws EVENLY to avoid cocking rabbet on pedestal
mounting face.
13. Apply a light coating of soapy water to inside rubber portion of seal head
and slide onto shaft sleeve. Slip shaft sleeve with seal head onto pump
shaft with polished face toward seal seat.
Do not touch or wipe face of polished surface part of seal head.
14. Replace any impeller shim(s) removed in disassembly.
15. Screw impeller back in place, tightening until it is against shaft sleeve.
16. Remount volute and position o-ring in place.
IMPORTANT: Always inspect o-ring. Replace when cracked or worn. Wet
o-ring with soapy water for ease of assembly.
17. Remount casing.

BEARING HOUSING SERVICE

1. Remove front pump assembly as described under "Mechanical Seal
Replacement"
2. Remove shaft bearing (Ref. No. 3) and shaft (Ref. No. 5) as an assembly
by first removing retaining ring (Ref. No. 1). Push shaft bearing assembly
out of pedestal (Ref. No. 6) by rapping on threaded end of shaft with a
rawhide mallet or block of wood and a hammer.
3. Ball bearings can now be removed from shaft.
4. If shaft bearings have been removed from shaft, replace by sliding bearing
on shaft to shoulder. Replace shaft bearing assembly by sliding assembly
into housing threaded end first. Push shaft bearing assembly completely
in by gently tapping on keyway end of shaft with a rawhide mallet. Replace
retaining ring.
5. Reassemble pump as described in "Mechanical Seal Replacement".
GPM of Water at Total Head in Feet
40' 50' 60'
123 110 90
1
3931-99
Max**
70' 80' Head
65 40 92 ft.
10/2016