Gorman-Rupp Pumps 12C20-B 1341727 and up - Manual (Page 33)

10 SERIES OM-00608
MAINTENANCE & REPAIR PAGE E - 10
shims (62) 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 bottle oiler and piping (63, 64 and 65).
Install the air vent and piping (15, 16 and 17).
Pump Casing Installation
Remove the hardware temporarily securing the
seal plate to the pedestal. Install the same thick­
ness of pump casing gaskets (41) as previously re­
moved and secure the pump casing (1) to the seal
plate and pedestal with the nuts (39). Do not fully
tighten the nuts at this time.
NOTE
The back cover assembly 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 (42) is also
recommended for maximum pump efficiency. Set
this clearance by adding or removing gaskets in
the pump casing gasket set (41) 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 (39) securing the pump casing to the pedes­
tal.
Suction Check Valve Installation
If the suction flange (58) was removed, install a
new gasket (55) and secure the suction flange to
the pump casing with the hardware (56 and 57).
Inspect the check valve components and replace
as required. If the check valve was disassembled,
position the check valve (8) against the adaptor (6).
Slide the spacer sleeves (7) through the holes in
the gasket and into the holes in the adaptor. Install
the backup plate (9) over the spacer sleeves and
secure with the nylock capscrews (10).
Reach through the back cover opening and posi­
tion the check valve adaptor in the slot in the suc­
tion flange (58). Secure the check valve in the suc­
tion flange with the check valve pin (4).
Check the operation of the check valve to ensure
proper seating and free movement.
Back Cover Installation
If the wear plate (42) was removed for replace­
ment, secure it to the back cover assembly (50) us­
ing the attaching hardware (43 and 44). The wear
plate must be concentric to prevent binding when
the back cover assembly is installed.
Clean any scale or debris from the contacting sur­
faces on the pump casing that might prevent a
good seal with the back cover.
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.
Replace the back cover gasket (49) and slide the
back cover assembly into the pump casing.
Secure the back cover assembly by installing the
clamp bar (46) and tightening the clamp bar screw
(48). Do not over‐tighten the clamp bar screw; it
should be just tight enough to seal the back cover
shoulder.
Check for scraping or binding between the impel­
ler and wear plate and correct any that exists be­
fore putting the pump back into service.
Final Pump Assembly
Secure the pump to the base with the previously re­
moved hardware. Be sure to reinstall any leveling
shims used under the pump casing or pedestal
mounting feet. Install the shaft key (26) and con­
nect the power source.
Be sure the pump and power source are securely
mounted to the base.