Operation; Cutter Replacement; Impeller Removal - Pentair MYERS MRGD200MC2 Owner's Manual

Operation / Maintenance

OPERATION

Hazardous cutter and possible
unexpected starts. Rotation of the
cutter with hands in the cutter
area can cause loss of fingers.
Disconnect the electrical power
and keep your hands away from the
pump inlet opening when working
on or handling the pump for any reason. Do not use
automatic reset controls with this pump.
Single phase units have an automatic overload protector
in the motor which will protect the motor from burning
out due to overheating/overloading. When the motor
cools down, the overload protector will automatically
reset and start the motor. This can happen at any time.
Three phase units require external overload protection.
If the overload trips frequently, check for the cause. It
could be:
• stuck impeller
• wrong/low voltage
• bad thermal overload protector
• electrical failure in the motor. If the motor has
electrically failed, replace the pump.
Grinder Assembly: The grinder unit consists of a rotary
cutter inside a stationary cutter ring. Persistent jamming
and clogging of the pump indicates dull or worn grinder
parts. If either the cutter ring or the rotary cutter is dull,
replace both.
NOTE: Normal domestic sewage will cause very little
dulling or wear of the grinder parts. However, pumping
abrasives (such as fine sand) will increase wear and tear
on the grinder and may make it necessary to replace the
grinder assembly frequently.
Lubrication: The pump is permanently lubricated and
the motor bearings are sealed. No oiling or greasing is
required.
The pump is not equipped with thermostats or a leak
sensor probe. Check the seal condition quarterly in
heavy duty service or annually in light duty service.
NOTE: Failure to monitor the seal condition voids the
warranty. Motors damaged by flooding of the motor
cavity due to seal or O-Ring failure may not be covered
under warranty.
NOTE: Reduce the number of bends in the discharge
piping to keep the outlet flow as smooth as possible.
Verify the capacity of the pump, by checking the
discharge. Verify that the pump is free from any vibration
and noise.
For continuous operation, the liquid level must be at
least 19-1/2" for a three-phase pump or 22-1/2" for a
single-phase pump to avoid overheating the motor.
Do not allow the pump to run in a dry sump. It will void
the warranty and may damage the pump.
Maintenance
Only qualified mechanics with proper tools and
knowledge should attempt to service this pump.
NOTE: Whenever bearing bracket is being removed
for service, remove oil and replace with new oil at
reassembly. Use only oil listed in parts list (Part No.
U197-8A). When filling with new oil, DO NOT overfill.
To allow room for expansion, use exactly 1.8 pints
(0.77 liters) of oil with a cold bearing bracket.

Cutter Replacement

The Key numbers given in these procedures refer to the
exploded view (Page 8).
Hazardous voltage, hazardous
cutter, and possible unexpected
starts. Disconnect the electrical
power and keep your hands away
from the pump inlet opening
when working on or handling the
pump for any reason. Do not use
automatic reset controls with this pump.
Heavy parts. Use a hoist to lift and control
the pump during repair.
NOTE: Be prepared to deal with a large quantity of oil
when draining the bearing bracket. Inspect the O-Rings
and castings for damage or evidence of leaks; check for
pinched or damaged wires.
1. Disconnect the electrical power supply.
2. Disconnect the discharge piping (this step is not
necessary if you have a guide-rail lift-out system).
3. Hoist the pump out of the pit using the lift-out system
or the handle (not the cord) and place the pump in a
suitable area where it can be cleaned.
4. Remove all scale and deposits from the pump.
Risk of infection from pathogens (such
as hepatitis) which can collect on pump during
normal operation. Submerge the complete pump in a
disinfectant solution (chlorox or chlorine) for at least
one hour before disassembly.
5. Wedge the shaft and cutter with a screwdriver in a
cutter ring slot and unscrew the cap nut (Key No. 24)
to release the rotating cutter (Key No. 21).
6. Unscrew four capscrews and use a screwdriver to pry
the cutter ring (Key No. 25) off of the volute.
7. Reverse steps 1 through 7 to reassemble the cutter.

Impeller Removal

1. Follow steps 1 through 7 under "Cutter
Replacement".
2. Unscrew the 4 capscrews holding the volute to the
seal plate and tap the volute to loosen it. Remove the
volute.
5