Gorman-Rupp Pumps 12B2-B 723756 and up - Manual (Page 33)

OM-00575 10 SERIES
MAINTENANCE & REPAIR PAGE E - 10
Lubricate the seal assembly as indicated in LU­
BRICATION after the impeller has been installed.
Impeller Installation and Adjustment
Inspect the impeller and replace it if cracked or
badly worn. Install the same thickness of impeller
shims (8) as previously removed, and screw the
impeller onto the shaft until tight.
A clearance of .020 to .040 inch (0,51 to 1,02 mm)
between the impeller and the seal plate is neces­
sary for maximum pump efficiency. Measure this
clearance and add or remove impeller shims until
this clearance is reached.
NOTE
Be sure the seal plate is tight against the pedestal
while measuring this clearance.
Install the automatic grease cup and piping (11, 12
and 13) in the seal plate. After the pump casing is
installed, lubricate the seal assembly as indicated
in LUBRICATION.
Pump Casing Installation
Remove the hardware temporarily securing the
seal plate to the pedestal. Install the same thick­
ness of pump casing gaskets (35) as previously re­
moved. Secure the pump casing (1) to the seal
plate and pedestal with the nuts (33). Do not fully
tighten the nuts at this time.
NOTE
The back cover assembly (41) must be in place to
adjust the impeller face clearance.
A clearance of .008 to .015 inch (0,20 to 0,38 mm)
between the impeller and the wear plate (37) is also
recommended for maximum pump efficiency. Set
this clearance by adding or removing gaskets in
the pump casing gasket set (35) until the impeller
scrapes against the wear plate when the shaft is
turned by hand. After the impeller scrapes, add ap­
proximately .008 inch (0,20 mm) of gaskets.
After the face clearance has been set, tighten the
nuts (33) securing the pump casing to the pedes­
tal.
Secure the pump casing to the base with the pre­
viously removed hardware. Be sure to reinstall any
leveling shims used under the mounting feet of the
pump casing.
Back Cover Installation
If the wear plate (37) was removed for replace­
ment, secure it to the cover plate (42) using the at­
taching hardware (38 and 39) at this time. The wear
plate must be concentric to prevent binding when
the back cover is installed.
Clean any scales or debris from the contacting sur­
faces on the pump casing that might prevent a
good seal with the back cover. Replace the back
cover gasket (40) and slide the back cover assem­
bly into the pump casing. Be sure the wear plate
does not bind against the impeller.
NOTE
To ease future disassembly, apply a film of grease
or `Never‐Seez' on the back cover shoulder, or any
surface that contacts the pump casing. This action
will reduce rust and scale build‐up.
Secure the back cover assembly by installing the
clamp bar (47) and tightening the clamp bar screw
(46). Do not over‐tighten the clamp bar screw; it
should be just tight enough to seal the back cover
shoulder.
Suction Check Valve Installation
Inspect components of the check valve assembly
(50) and replace as required. If separated at disas­
sembly, assemble the check valve weights (51 and
55) to the check valve gasket (54) with the hard­
ware (52 and 53).
Position the check valve assembly in the suction
port with the large weight toward the inside of the
pump casing. Install the suction flange (56) and se­
cure with the hardware (48 and 49). Check the op­
eration of the check valve to ensure proper seating
and free movement.
Final Pump Assembly
Be sure the pump and power source are securely
mounted to the base. Reconnect the power source
to the pump.
Install the suction and discharge lines and open all
valves. Make certain that all piping connections are
tight, properly supported and secure.