GORMAN-RUPP PUMPS 81 1/2D3-X1 3P User manual

OM-00760-06
January 23, 1980
Rev. B 07‐02‐19
GORMAN‐RUPP PUMPS
www.grpumps.com
1980 Gorman‐Rupp Pumps Printed in U.S.A.
INSTALLATION, OPERATION,
AND MAINTENANCE MANUAL
WITH PARTS LIST
80 SERIES PUMP
MODEL
81 1/2D3-X1 3P

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Gorman‐Rupp pump online at
www.grpumps.com
Valid serial number and e‐mail address required.
RECORD YOUR PUMP MODEL AND SERIAL NUMBER
Please record your pump model and serial number in the
spaces provided below. Your Gorman‐Rupp distributor
needs this information when you require parts or service.
Pump Model:
Serial Number:

TABLE OF CONTENTS
i
INTRODUCTION PAGE I - 1.................................................
SAFETY ‐ SECTION A PAGE A - 1............................................
INSTALLATION - SECTION B PAGE B - 1....................................
Pump Dimensions PAGE B - 1.....................................................
PREINSTALLATION INSPECTION PAGE B - 1............................................
POSITIONING PUMP PAGE B - 2.......................................................
Lifting PAGE B - 2.................................................................
Mounting PAGE B - 2.............................................................
SUCTION AND DISCHARGE PIPING PAGE B - 2.........................................
Materials PAGE B - 2..............................................................
Line Configuration PAGE B - 2......................................................
Connections to Pump PAGE B - 3..................................................
Gauges PAGE B - 3...............................................................
SUCTION LINES PAGE B - 3...........................................................
Fittings PAGE B - 3...............................................................
Strainers PAGE B - 3..............................................................
Sealing PAGE B - 3...............................................................
Suction Lines In Sumps PAGE B - 3.................................................
Suction Line Positioning PAGE B - 4................................................
DISCHARGE LINES PAGE B - 4........................................................
Siphoning PAGE B - 4.............................................................
Valves PAGE B - 4................................................................
Bypass Lines PAGE B - 5..........................................................
ELECTRICAL CONNECTIONS PAGE B - 5...............................................
OPERATION - SECTION C PAGE C - 1......................................
PRIMING PAGE C - 1.................................................................
STARTING PAGE C - 1................................................................
Rotation PAGE C - 1..............................................................
OPERATION PAGE C - 2..............................................................
Lines With a Bypass PAGE C - 2....................................................
Lines Without a Bypass PAGE C - 2.................................................
Leakage PAGE C - 2..............................................................
Liquid Temperature And Overheating PAGE C - 2.....................................
Strainer Check PAGE C - 2.........................................................
Pump Vacuum Check PAGE C - 2..................................................
STOPPING PAGE C - 3................................................................
Cold Weather Preservation PAGE C - 3..............................................
TROUBLESHOOTING - SECTION D PAGE D - 1..............................
PREVENTIVE MAINTENANCE PAGE D - 3...............................................
PUMP MAINTENANCE AND REPAIR ‐ SECTION E PAGE E - 1.................
STANDARD PERFORMANCE CURVE PAGE E - 1........................................

TABLE OF CONTENTS
(continued)
ii
PARTS LIST:
Pump Model PAGE E - 3..........................................................
PUMP AND SEAL DISASSEMBLY AND REASSEMBLY PAGE E - 4.........................
Pump Casing and Vane Plate Removal PAGE E - 5...................................
Impeller Removal PAGE E - 5......................................................
Seal Removal PAGE E - 5..........................................................
Seal Reassembly and Installation PAGE E - 5........................................
Impeller Installation PAGE E - 7.....................................................
Vane Plate and Pump Casing Installation PAGE E - 7.................................
Final Pump Assembly PAGE E - 7..................................................
LUBRICATION PAGE E - 7.............................................................
Seal Assembly PAGE E - 7.........................................................

80 SERIES OM-00760
PAGE I - 1INTRODUCTION
INTRODUCTION
Thank You for purchasing a Gorman‐Rupp pump.
Read this manual carefully to learn how to safely
install and operate your pump. Failure to do so
could result in personal injury or damage to the
pump.
This pump is an 80 Series, semi‐open impeller, self‐
priming centrifugal model. It is close‐coupled to a 1
H.P., three phase, explosion‐proof electric motor.
The basic material of construction for wetted parts
is gray iron, with a bronze impeller and stainless
steel motor shaft. The pump is designed to handle
petroleum products or other industrial liquids that
do not contain large entrained solids.
This manual will alert personnel to known proce
dures which require special attention, to those
which could damage equipment, and to those
which could be dangerous to personnel. However,
this manual cannot possibly anticipate and provide
detailed precautions for every situation that might
occur during maintenance of the unit. Therefore, it
is the responsibility of the owner/maintenance per
sonnel to ensure that only safe, established main
tenance procedures are used, and that any proce
dures not addressed in this manual are performed
only after establishing that neither personal safety
nor pump integrity are compromised by such prac
tices.
For information or technical assistance on the mo
tor, contact the motor manufacturer's local dealer
or representative.
If there are any questions regarding the pump or
its application which are not covered in this man
ual or in other literature accompanying this unit,
please contact your Gorman‐Rupp distributor, or:
The Gorman‐Rupp Company
P.O. Box 1217
Mansfield, Ohio 44901-1217
Phone: [phone]
or:
Gorman‐Rupp of Canada Limited
70 Burwell Road
St. Thomas, Ontario N5P 3R7
Phone: [phone]
The following are used to alert maintenance per
sonnel to procedures which require special atten
tion, to those which could damage equipment, and
to those which could be dangerous to personnel:
Immediate hazards which WILL result in
severe personal injury or death. These
instructions describe the procedure re
quired and the injury which will result
from failure to follow the procedure.
Hazards or unsafe practices which
COULD result in severe personal injury
or death. These instructions describe
the procedure required and the injury
which could result from failure to follow
the procedure.
Hazards or unsafe practices which COULD
result in minor personal injury or product
or property damage. These instructions
describe the requirements and the possi
ble damage which could result from failure
to follow the procedure.
NOTE
Instructions to aid in installation, operation, and
maintenance or which clarify a procedure.

80 SERIES OM-00760
PAGE A - 1SAFETY
SAFETY - SECTION A
This information applies to 80 Series
electric motor driven pumps. Refer to
the manual accompanying the motor
before attempting to begin operation.
This manual will alert personnel to
known procedures which require spe
cial attention, to those which could
damage equipment, and to those which
could be dangerous to personnel. How
ever, this manual cannot possibly pro
vide detailed instructions and precau
tions for each specific application or for
every situation that might occur during
maintenance of the unit. Therefore, it is
the responsibility of the owner, installer
and/or maintenance personnel to en
sure that applications and/or mainte
nance procedures not addressed in this
manual are performed only after estab
lishing that neither personal safety nor
pump integrity are compromised by
such applications or procedures.
Before attempting to open or service the
pump:
1. Familiarize yourself with this man
ual.
2. Disconnect the incoming power to
the motor and lock it out to ensure
that the pump will remain inopera
tive.
3. Allow the pump to completely cool
if overheated.
4. Check the temperature before
opening any covers, plates, or
plugs.
5. Close the suction and discharge
valves.
6. Vent the pump slowly and cau
tiously.
7. Drain the pump.
This pump is designed to handle petro
leum products or other industrial liq
uids that do not contain large entrained
solids. Do not attempt to pump liquids
which may damage the pump or endan
ger personnel as a result of pump fai
lure.
This pump is designed to handle petro
leum products or other industrial liq
uids that do not contain large entrained
solids. All controls must meet industry
standards and codes for use in an ex
plosive atmosphere. Do not attempt to
pump liquids for which the pump and/or
controls have not been approved, or
which may damage the pump or endan
ger personnel as a result of pump fail
ure.
Be certain proper safety practices are
followed before operating or servicing
the pump. Provide adequate ventilation,
prohibit smoking, wear static‐resistant
clothing and shoes. Clean up all fuel
spills immediately after occurrence.
Do not install and operate a non‐explo
sion proof motor in an explosive atmo
sphere. Install, connect, and operate
the motor in accordance with the Na
tional Electric Code and all local codes.
If there is a conflict between the instruc
tions in the manual accompanying the
unit and the National Electric Code or

80 SERIESOM-00760
PAGE A - 2 SAFETY
the applicable local code, the National
or local code shall take precedence.
Because this pump is designed to han
dle volatile and/or flammable liquids,
overheating may produce dangerous
fumes. Take precautions to ensure the
area surrounding the pump is ade
quately ventilated. Allow the pump to
cool and use extreme caution when
venting the pump, or when removing
covers, plates, plugs, or fittings.
After the pump has been positioned,
make certain that the pump and all pip
ing connections are tight, properly sup
ported and secure before operation.
Do not remove plates, covers, gauges,
pipe plugs, or fittings from an over
heated pump. Vapor pressure within the
pump can cause parts being disen
gaged to be ejected with great force. Al
low the pump to cool before servicing.
Do not operate the pump against a
closed discharge valve for long periods
of time. If operated against a closed dis
charge valve, pump components will
deteriorate, and the liquid could come
to a boil, build pressure, and cause the
pump casing to rupture or explode.
Overheated pumps can cause severe
burns and injuries. If overheating of the
pump occurs:
1. Stop the pump immediately.
2. Ventilate the area.
3. Allow the pump to completely cool.
4. Check the temperature before
opening any covers, plates,
gauges, or plugs.
5. Vent the pump slowly and cau
tiously.
6. Refer to instructions in this manual
before restarting the pump.
The electrical power used to operate
this pump is high enough to cause inju
ry or death. Obtain the services of a qu
alified electrician to troubleshoot, test
and/or service the electrical compo
nents of this pump.
Use lifting and moving equipment in
good repair and with adequate capacity
to prevent injuries to personnel or dam
age to equipment. Suction and dis
charge hoses and piping must be re
moved from the pump before lifting.
Pumps and related equipment must be in
stalled and operated according to all na
tional, local and industry standards.

OM-0076080 SERIES
PAGE B - 1INSTALLATION
INSTALLATION - SECTION B
Review all SAFETY information in Section A.
Since pump installations are seldom identical, this
section offers only general recommendations and
practices required to inspect, position, and ar
range the pump and piping.
Most of the information pertains to a standard
static lift application where the pump is posi
tioned above the free level of liquid to be pumped.
If installed in a flooded suction application where
the liquid is supplied to the pump under pressure,
some of the information such as mounting, line
configuration, and priming must be tailored to the
specific application. Since the pressure supplied
to the pump is critical to performance and safety,
be sure to limit the incoming pressure to 50% of
the maximum permissible operating pressure as
shown on the pump performance curve.
For further assistance, contact your Gorman‐Rupp
distributor or the Gorman‐Rupp Company.
Pump Dimensions
See Figure 1 for the approximate physical dimen
sions of this pump.
OUTLINE DRAWING
Figure 1. Pump Models 81 1/2D3-X1 3P
PREINSTALLATION INSPECTION
The pump assembly was inspected and tested be
fore shipment from the factory. Before installation,
inspect the pump for damage which may have oc
curred during shipment. Check as follows:
a. Inspect the pump and motor for cracks,
dents, damaged threads, and other obvious
damage.
b. Check for and tighten loose attaching hard
ware. Since gaskets tend to shrink after dry

OM-00760 80 SERIES
PAGE B - 2 INSTALLATION
ing, check for loose hardware at mating sur
faces.
c. Carefully read all warnings and cautions con
tained in this manual or affixed to the pump,
and perform all duties indicated. Note the di
rection of rotation indicated on the pump.
Check that the pump shaft rotates counter
clockwise when facing the impeller.
Only operate this pump in the direction in
dicated by the arrow on the pump body
and on the accompanying decal. Refer to
ROTATION in OPERATION, Section C.
d. Check levels and lubricate as necessary. Re
fer to LUBRICATION in the MAINTENANCE
AND REPAIR section of this manual and per
form duties as instructed.
e. If the pump and motor have been stored for
more than 12 months, some of the compo
nents or lubricants may have exceeded their
maximum shelf life. These must be inspected
or replaced to ensure maximum pump serv
ice.
If the maximum shelf life has been exceeded, or if
anything appears to be abnormal, contact your
Gorman‐Rupp distributor or the factory to deter
mine the repair or updating policy. Do not put the
pump into service until appropriate action has
been taken.
The electrical power used to operate
this pump is high enough to cause inju
ry or death. Obtain the services of a qu
alified electrician to troubleshoot, test
and/or service the electrical compo
nents of this pump.
POSITIONING PUMP
Lifting
Pump unit weights will vary depending on the
mounting and drive provided. Check the shipping
tag on the unit packaging for the actual weight, and
use lifting equipment with appropriate capacity.
Drain the pump and remove all customer‐installed
equipment such as suction and discharge hoses
or piping before attempting to lift existing, installed
units.
The pump assembly can be seriously
damaged if the cables or chains used to lift
and move the unit are improperly wrapped
around the pump.
Mounting
Locate the pump in an accessible place as close as
practical to the liquid being pumped. Level mount
ing is essential for proper operation.
The intermediate is equipped with mounting foot
holes for mounting the pump to a base.
SUCTION AND DISCHARGE PIPING
Pump performance is adversely effected by in
creased suction lift, discharge elevation, and fric
tion losses. See the performance curve and oper
ating range shown on Page E‐1 to be sure your
overall application allows pump to operate within
the safe operation range.
Materials
Either pipe or hose maybe used for suction and
discharge lines; however, the materials must be
compatible with the liquid being pumped. If hose is
used in suction lines, it must be the rigid‐wall, rein
forced type to prevent collapse under suction. Us
ing piping couplings in suction lines is not recom
mended.
Line Configuration
Keep suction and discharge lines as straight as
possible to minimize friction losses. Make mini

OM-0076080 SERIES
PAGE B - 3INSTALLATION
mum use of elbows and fittings, which substan
tially increase friction loss. If elbows are necessary,
use the long‐radius type to minimize friction loss.
Connections to Pump
Before tightening a connecting flange, align it ex
actly with the pump port. Never pull a pipe line into
place by tightening the flange bolts and/or cou
plings.
Lines near the pump must be independently sup
ported to avoid strain on the pump which could
cause excessive vibration, decreased bearing life,
and increased shaft and seal wear. If hose‐type
lines are used, they should have adequate support
to secure them when filled with liquid and under
pressure.
Gauges
Most pumps are drilled and tapped for installing
discharge pressure and vacuum suction gauges.
If these gauges are desired for pumps that are not
tapped, drill and tap the suction and discharge
lines not less than 18 inches (457,2 mm) from the
suction and discharge ports and install the lines.
Installation closer to the pump may result in erratic
readings.
SUCTION LINES
To avoid air pockets which could affect pump prim
ing, the suction line must be as short and direct as
possible. When operation involves a suction lift, the
line must always slope upward to the pump from
the source of the liquid being pumped; if the line
slopes down to the pump at any point along the
suction run, air pockets will be created.
Fittings
Suction lines should be the same size as the pump
inlet. If reducers are used in suction lines, they
should be the eccentric type, and should be in
stalled with the flat part of the reducers uppermost
to avoid creating air pockets. Valves are not nor
mally used in suction lines, but if a valve is used,
install it with the stem horizontal to avoid air pock
ets.
Strainers
If a strainer is furnished with the pump, be certain
to use it; any spherical solids which pass through a
strainer furnished with the pump will also pass
through the pump itself.
If a strainer is not furnished with the pump, but is
installed by the pump user, make certain that the
total area of the openings in the strainer is at least
three or four times the cross section of the suction
line, and that the openings will not permit passage
of solids larger than the solids handling capability
of the pump.
This pump is designed to handle up to 1/4‐inch
(6,4 mm) diameter spherical solids.
Sealing
Since even a slight leak will affect priming, head,
and capacity, especially when operating with a
high suction lift, all connections in the suction line
should be sealed with pipe dope to ensure an air
tight seal. Follow the sealant manufacturer's rec
ommendations when selecting and applying the
pipe dope. The pipe dope should be compatible
with the liquid being pumped.
Suction Lines In Sumps
If a single suction line is installed in a sump, it
should be positioned away from the wall of the
sump at a distance equal to 1 1/2 times the diame
ter of the suction line.
If there is a liquid flow from an open pipe into the
sump, the flow should be kept away from the suc
tion inlet because the inflow will carry air down into
the sump, and air entering the suction line will re
duce pump efficiency.
If it is necessary to position inflow close to the suc
tion inlet, install a baffle between the inflow and the
suction inlet at a distance 1 1/2 times the diameter
of the suction pipe. The baffle will allow entrained
air to escape from the liquid before it is drawn into
the suction inlet.
If two suction lines are installed in a single sump,
the flow paths may interact, reducing the efficiency
of one or both pumps. To avoid this, position the
suction inlets so that they are separated by a dis

OM-00760 80 SERIES
PAGE B - 4 INSTALLATION
tance equal to at least 3 times the diameter of the
suction pipe.
Suction Line Positioning
The depth of submergence of the suction line is
critical to efficient pump operation. Figure 2 shows
recommended minimum submergence vs. veloc
ity.
NOTE
The pipe submergence required may be reduced
by installing a standard pipe increaser fitting at the
end of the suction line. The larger opening size will
reduce the inlet velocity. Calculate the required
submergence using the following formula based
on the increased opening size (area or diameter).
Figure 2. Recommended Minimum Suction Line Submergence vs. Velocity
DISCHARGE LINES
Siphoning
Do not terminate the discharge line at a level lower
than that of the liquid being pumped unless a si
phon breaker is used in the line. Otherwise, a si
phoning action causing damage to the pump
could result.
Valves
If a throttling valve is desired in the discharge line,
use a valve as large as the largest pipe to minimize
friction losses. Never install a throttling valve in a
suction line.
A check valve in the discharge line is normally rec
ommended, but it is not necessary in low dis
charge head applications.
With high discharge heads, it is recommended that
a throttling valve and a system check valve be in
stalled in the discharge line to protect the pump
from excessive shock pressure and reverse rota
tion when it is stopped.
If the application involves a high discharge
head, gradually close the discharge
throttling valve before stopping the pump.

OM-0076080 SERIES
PAGE B - 5INSTALLATION
Bypass Lines
If it is necessary to permit the escape of air to atmo
sphere on initial priming or during the repriming
cycle, install an air bypass line ‐ sized so that it will
not affect the pump discharge capacity ‐ between
the pump and the discharge check valve. Since
this pump does not use a suction check valve, the
discharge end of the bypass line must be sub
merged in the liquid being pumped in order to
maintain suction.
NOTE
The bypass line may clog frequently if the liquid
contains solids and the valve remains closed. If this
condition occurs, either use a larger bypass line or
leave the shut‐off valve open during pumping.
ELECTRICAL CONNECTIONS
This pump is driven by an electric motor. Check
that the electrical service available matches the
motor requirements stamped on the motor name
plate before connecting the motor to the incoming
power.
The electrical power used to operate the
pump is high enough to cause injury or
death. Obtain the services of a qualified
electrician to make all electrical con
nections.
Do not install and operate a non‐explo
sion proof motor in an explosive atmo
sphere. Install, connect, and operate
the motor in accordance with The Na
tional Electric Code and all local codes.
If there is a conflict between the instruc
tions in the manual accompanying the
unit and The National Electric Code or
the applicable local code, The National
or local code shall take precedence.
Refer to the following motor data before making
electrical connections.
VOLTAGE PHASE HP Hz RPM F.L. AMPS
230/460 3 60 3450 3.6/1.8
MODEL
81 1/2D3-X1 3P 1
GROUNDING
Because this pump is used to handle volatile or
flammable liquids, the unit must be grounded by
attaching a ground wire assembly to a ground rod
in order to eliminate electrostatic build‐up by the
liquid being pumped. Install the ground rod in ac
cordance with the National Electrical Codes and all
local codes. Be sure the fastening device makes a
tight electrical connection with the rod and the
pump.
Inspect and test the ground wire assembly
for conductivity. Replace a broken or
frayed wire before resuming operation.

80 SERIES OM-00760
OPERATION PAGE C - 1
OPERATION - SECTION C
Review all SAFETY information in Section A.
Follow the instructions on all tags, labels and
decals attached to the pump.
This pump is designed to handle petro
leum products and other industrial liq
uids that do not contain large entrained
solids. Do not attempt to pump liquids
which may damage the pump or endan
ger personnel as a result of pump fail
ure.
Pump speed and operating conditions
must be within the performance range
shown on page E‐1.
PRIMING
Install the pump and piping as described in IN
STALLATION. Make sure that the piping connec
tions are tight, and that the pump is securely
mounted. Check that the pump is properly lubri
cated (see LUBRICATION in MAINTENANCE
AND REPAIR).
This pump is self‐priming, but the pump should
never be operated unless there is liquid in the
pump casing.
Never operate this pump unless there is
liquid in the pump casing. The pump will
not prime when dry. extended operation of
a dry pump will destroy the seal assembly.
Add liquid to the pump casing when:
1. The pump is being put into service for the
first time.
2. The pump has not been used for a consider
able length of time.
3. The liquid in the pump casing has evapo
rated.
Once the pump casing has been filled, the pump
will prime and reprime as necessary.
After filling the pump casing, reinstall
and tighten the fill plug. Do not attempt
to operate the pump unless all connect
ing piping is securely installed. Other
wise, liquid in the pump forced out
under pressure could cause injury to
personnel.
To fill the pump, remove the pump casing fill cover
or fill plug in the top of the casing, and add clean
liquid until the casing is filled. Replace the fill cover
or fill plug before operating the pump.
STARTING
Rotation
The correct direction of pump rotation is indicated
by an arrow on the pump body and on the accom
panying decal.
To check rotation, briefly apply power to the motor
observing the direction of shaft rotation through
the “window” in the side of the intermediate.
If rotation is incorrect on a three‐phase motor, have
a qualified electrician interchange any two of the
three phase wires to change direction.
OPERATION
Lines With a Bypass
Since this pump does not have a suction check
valve, the discharge end of the bypass line must be
submerged in order to maintain suction.

80 SERIESOM-00760
OPERATIONPAGE C - 2
Close the throttling valve in the discharge line and
open the shut‐off valve in the bypass line so that
the pump will not have to prime against the weight
of the liquid in the discharge line. Start the motor.
When the pump has primed and liquid is flowing
steadily through the bypass line, close the bypass
shut‐off valve and open the discharge throttling
valve.
Lines Without a Bypass
Open all valves in the discharge line and start the
power source. Priming is indicated by a positive
reading on the discharge pressure gauge or by a
quieter operation. The pump may not prime imme
diately because the suction line must first fill with
liquid. If the pump fails to prime within five minutes,
stop it and check the suction line for leaks.
After the pump has been primed, partially close the
discharge line throttling valve in order to fill the line
slowly and guard against excessive shock pres
sure which could damage pipe ends, gaskets,
sprinkler heads, and any other fixtures connected
to the line. When the discharge line is completely
filled, adjust the throttling valve to the required flow
rate.
Do not operate the pump against a
closed discharge throttling valve for
long periods of time. If operated against
a closed discharge throttling valve,
pump components will deteriorate, and
the liquid could come to a boil, build
pressure, and cause the pump casing to
rupture or explode.
Leakage
No leakage should be visible at pump mating sur
faces, or at pump connections or fittings. Keep all
line connections and fittings tight to maintain maxi
mum pump efficiency.
Liquid Temperature And Overheating
The maximum liquid temperature for this pump is
160 F (71 C). Do not apply it at a higher operat
ing temperature.
Overheating can occur if operated with the valves
in the suction or discharge lines closed. Operating
against closed valves could bring the liquid to a
boil, build pressure, and cause the pump to rup
ture or explode. If overheating occurs, stop the
pump and allow it to cool before servicing it. Refill
the pump casing with cool liquid.
Allow an over‐heated pump to com
pletely cool before servicing. Do not re
move plates, covers, gauges, or fittings
from an over‐heated pump. Liquid with
in the pump can reach boiling tempera
tures, and vapor pressure within the
pump can cause parts being disen
gaged to be ejected with great force. Af
ter the pump completely cools, drain the
liquid from the pump by removing the
casing drain plug. Use caution when re
moving the plug to prevent injury to per
sonnel from hot liquid.
Strainer Check
If a suction strainer has been shipped with the
pump or installed by the user, check the strainer
regularly, and clean it as necessary. The strainer
should also be checked if pump flow rate begins to
drop. If a vacuum suction gauge has been in
stalled, monitor and record the readings regularly
to detect strainer blockage.
Never introduce air or steam pressure into the
pump casing or piping to remove a blockage. This
could result in personal injury or damage to the
equipment. If backflushing is absolutely neces
sary, liquid pressure must be limited to 50% of the
maximum permissible operating pressure shown
on the pump performance curve.
Pump Vacuum Check
With the pump inoperative, install a vacuum gauge
in the system, using pipe dope on the threads.

80 SERIES OM-00760
OPERATION PAGE C - 3
Block the suction line and start the pump. At oper
ating speed the pump should pull a vacuum of 20
inches (508,0 mm) or more of mercury. If it does
not, check for air leaks in the seal, gasket, or dis
charge valve.
Open the suction line, and read the vacuum gauge
with the pump primed and at operation speed.
Shut off the pump. The vacuum gauge reading will
immediately drop proportionate to static suction
lift, and should then stabilize. If the vacuum reading
falls off rapidly after stabilization, an air leak exists.
Before checking for the source of the leak, check
the point of installation of the vacuum gauge.
STOPPING
After stopping the pump, disconnect the incoming
power to the motor and lock it out to ensure that the
pump will remain inoperative.
Do not operate the pump against a
closed discharge throttling valve for
long periods of time. If operated against
a closed discharge throttling valve,
pump components will deteriorate, and
the liquid could come to a boil, build
pressure, and cause the pump casing to
rupture or explode.
Cold Weather Preservation
In below freezing conditions, drain the pump to
prevent damage from freezing. Also, clean out any
solids by flushing with a hose. Operate the pump
for approximately one minute; this will remove any
remaining liquid that could freeze the pump rotat
ing parts. If the pump will be idle for more than a
few hours, drain the pump, and flush it thoroughly
with clean liquid. Operate the pump during the
draining process.

TROUBLE POSSIBLE CAUSE PROBABLE REMEDY
PUMP FAILS TO
PRIME
Strainer clogged. Check strainer and clean if neces
sary.
Suction lift or discharge head too high. Check piping installation and install
bypass line if needed. See INSTAL
LATION.
Leaking or worn seal or pump gasket. Check pump vacuum. Replace
leaking or worn seal or gasket.
Lining of suction hose collapsed. Replace suction hose.
Air leak in suction line. Correct leak.
PUMP STOPS OR
FAILS TO DELIVER
RATED FLOW OR
PRESSURE
Air leak in suction line. Correct leak.
Lining of suction hose collapsed. Replace suction hose.
Not enough liquid in casing. Add liquid to casing. See PRIMING.
Suction check valve contaminated or
damaged.
Clean or replace check valve.
Suction intake not submerged at
proper level or sump too small.
Check installation and correct
submergence as needed.
Impeller or other wearing parts worn
or damaged.
Replace worn or damaged parts.
Check that impeller is properly
centered and rotates freely.
OM-0076080 SERIES
TROUBLESHOOTING PAGE D - 1
TROUBLESHOOTING - SECTION D
Review all SAFETY information in Section A.
Before attempting to open or service the
pump:
1. Familiarize yourself with this manual.
2. Disconnect the incoming power to
the motor and lock it out to ensure
that the pump will remain inoperative.
3. Allow the pump to completely cool if
overheated.
4. Check the temperature before open
ing any covers, plates, or plugs.
5. Close the suction and discharge
valves.
6. Vent the pump slowly and cautiously.
7. Drain the pump.

TROUBLE POSSIBLE CAUSE PROBABLE REMEDY
PUMP STOPS OR
FAILS TO DELIVER
RATED FLOW OR
PRESSURE (cont.)
PUMP REQUIRES
TOO MUCH
POWER
PUMP CLOGS
FREQUENTLY
Free impeller of debris.Impeller clogged.
Discharge head too low.
Dilute if possible.Liquid solution too thick.
Adjust discharge valve.
Open discharge valve fully to in
crease flow rate, and run motor at
maximum governed speed.
Discharge flow too slow.
EXCESSIVE NOISE Cavitation in pump. Reduce suction lift and/or friction
losses in suction line. Record vac
uum and pressure gauge readings
and consult local representative or
factory.
Secure mounting hardware.Pump or drive not securely mounted.
Locate and eliminate source of air
bubble.
Pumping entrained air.
Suction check valve or foot valve
clogged or binding.
Clean valve.
Suction lift or discharge head too high. Check piping installation and install
bypass line if needed. See INSTAL
LATION.
Impeller clogged or damaged. Clean out debris; replace damaged
parts.
Leaking or worn seal or pump gasket. Check pump vacuum. Replace
leaking or worn seal or gasket.
Low or incorrect voltage. Measure control box voltage, both
when pump is running and when
shut off.
No voltage at line side of circuit
breaker.
Check power source for blown fuse,
open circuit breaker or control box,
broken lead, or loose connection.
Pump running backwards. Check direction of rotation and
correct by interchanging any two
motor leads at control box. (See
Pump Rotation, Section C).
Motor shaft or bearings defective. Disassemble pump and check mo
tor and bearings.
OM-00760 80 SERIES
TROUBLESHOOTINGPAGE D - 2

OM-0076080 SERIES
TROUBLESHOOTING PAGE D - 3
PREVENTIVE MAINTENANCE
Since pump applications are seldom identical, and
pump wear is directly affected by such things as
the abrasive qualities, pressure and temperature
of the liquid being pumped, this section is intended
only to provide general recommendations and
practices for preventive maintenance. Regardless
of the application however, following a routine pre
ventive maintenance schedule will help assure
trouble‐free performance and long life from your
Gorman‐Rupp pump. For specific questions con
cerning your application, contact your Gorman‐
Rupp distributor or the Gorman‐Rupp Company.
Record keeping is an essential component of a
good preventive maintenance program. Changes
in suction and discharge gauge readings (if so
equipped) between regularly scheduled inspec
tions can indicate problems that can be corrected
before system damage or catastrophic failure oc
curs. The appearance of wearing parts should also
be documented at each inspection for comparison
as well. Also, if records indicate that a certain part
(such as the seal) fails at approximately the same
duty cycle, the part can be checked and replaced
before failure occurs, reducing unscheduled down
time.
For new applications, a first inspection of wearing
parts at 250 hours will give insight into the wear rate
for your particular application. Subsequent inspec
tions should be performed at the intervals shown
on the chart below. Critical applications should be
inspected more frequently.
General Condition (Temperature, Unusual
Noises or Vibrations, Cracks, Leaks,
Loose Hardware, Etc.) I
Pump Performance (Gauges, Speed, Flow) I
Bearing Lubrication I R
Seal Lubrication (And Packing Adjustment,
If So Equipped) I R
V‐Belts (If So Equipped) I
Air Release Valve Plunger Rod (If So Equipped) I C
Front Impeller Clearance (Wear Plate) I
Rear Impeller Clearance (Seal Plate) I
Check Valve I
Pressure Relief Valve (If So Equipped) C
Pump and Driver Alignment I
Shaft Deflection I
Bearings I
Bearing Housing I
Piping I
Driver Lubrication - See Mfgr's Literature
Legend:
I = Inspect, Clean, Adjust, Repair or Replace as Necessary
C = Clean
R = Replace
* Service interval based on an intermittent duty cycle equal to approximately 4000 hours annually.
Adjust schedule as required for lower or higher duty cycles or extreme operating conditions.
Preventive Maintenance Schedule
Item Daily Weekly Monthly Semi‐
Annually
Annually
Service Interval*

80 SERIES OM-00760
MAINTENANCE & REPAIR PAGE E - 1
PUMP MAINTENANCE AND REPAIR ‐ SECTION E
MAINTENANCE AND REPAIR OF THE WEARING PARTS OF THE PUMP WILL MAINTAIN PEAK
OPERATING PERFORMANCE.
STANDARD PERFORMANCE FOR PUMP MODEL 81 1/2D3-X1 3P
Based on 70F (21C) clear water at sea level
with minimum suction lift. Since pump installations
are seldom identical, your performance may be dif
ferent due to such factors as viscosity, specific
gravity, elevation, temperature, and impeller trim.
If your pump serial number is followed by an “N”,
your pump is NOT a standard production model.
Contact the Gorman‐Rupp Company to verify per
formance or part numbers.
Pump speed and operating condition
points must be within the continuous per
formance range shown on the curve.

80 SERIESOM-00760
MAINTENANCE & REPAIRPAGE E - 2
SECTION DRAWING
PARTS PAGE
Figure 1. Pump Model 81 1/2D3-X1 3P