
Doc. No.: OMS500000104
Rev: A Page 19 of 42
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property of FMC Technologies, and may not be reproduced, disclosed, or made public in any manner prior to express written authorization by FMC.
9.0
Service Procedures
FMC pumps are designed to simplify all required maintenance. The following sections
illustrate a step-by-step procedure for performing most common service needs of a pump. Read
and understand each section completely before attempting to service the pump.
9.1
Replacing Plunger Packing
1. To make service easier, it is suggested that several gallons of clean water be pumped
through the M28 before any service procedures that involve fluid end components are
started. This action will remove a significant portion of contaminants left in the fluid
cylinder by the normal pumpage and improve the ability to work with the parts or spot
potential problem areas. Refer to the following page for the position of parts.
2. Bleed off all pressure inside pump fluid end before starting any service work. Shut the
valve on the inlet piping if provided to prevent flow of liquid from the source into the
pump during service. CHECK TO INSURE THAT THE POWER IS LOCKED
OUT.
3. Unbolt the plunger clamps (15) and remove them from the plungers (46) and plunger
rods (6). Remove the nuts (66) holding the stuffing box clamps (42) to the fluid cylinder
(38) and remove the stuffing box clamps (42).
4. Rotate the crankshaft by hand until one of the plunger rods (6) is fully retracted from the
plunger (46). Slide the plunger and stuffing box out of the cradle of the pump as a single
unit. Repeat this procedure for the other two plunger stuffing box assemblies.
5. Loosen the set screw (72) locking the threads on the adjusting nut (45) and unscrew the
adjusting nut. Use caution because the packing (43) is spring loaded. Pull the plunger
(46) from the assembly and remove the packing (43).